essay on aquatic life

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Marine life

Our ocean, coasts, and estuaries are home to diverse living things. These organisms take many forms, from the tiniest single-celled plankton to the largest animal on Earth, the blue whale. Understanding the life cycles, habits, habitats, and inter-relationships of marine life contributes to our understanding of the planet as a whole. Human influences and reliance on these species, as well as changing environmental conditions, will determine the future health of these marine inhabitants. Toxic spills , oxygen-depleted dead zones, marine debris , increasing ocean temperatures, overfishing, and shoreline development are daily threats to marine life. Part of NOAA's mission is to help protect these organisms and their habitats.

Food webs describe who eats whom in an ecological community. Made of interconnected food chains, food webs help us understand how changes to ecosystems — say, removing a top predator or adding nutrients — affect many different species, both directly and indirectly.

Phytoplankton and algae form the bases of aquatic food webs. They are eaten by primary consumers like zooplankton, small fish, and crustaceans. Primary consumers are in turn eaten by fish, small sharks, corals, and baleen whales. Top ocean predators include large sharks, billfish, dolphins, toothed whales, and large seals. Humans consume aquatic life from every section of this food web.

Coral reefs are some of the most diverse ecosystems in the world. Coral polyps , the animals primarily responsible for building reefs, can take many forms: large reef building colonies, graceful flowing fans, and even small, solitary organisms. Thousands of species of corals have been discovered; some live in warm, shallow, tropical seas and others in the cold, dark depths of the ocean.

Seafood plays an essential role in feeding the world’s growing population. Healthy fish populations lead to healthy oceans and it's our responsibility to be a part of the solution. The resilience of our marine ecosystems and coastal communities depend on sustainable fisheries.

Estuaries are areas of water and shoreline where rivers meet the ocean or another large body of water, such as one of the Great Lakes. Organisms that live in estuaries must be adapted to these dynamic environments, where there are variations in water chemistry including salinity, as well as physical changes like the rise and fall of tides. Despite these challenges, estuaries are also very productive ecosystems. They receive nutrients from both bodies of water and can support a variety of life. Because of their access to food, water, and shipping routes, people often live near estuaries and can impact the health of the ecosystem.

Marine mammals are found in marine ecosystems around the globe. They are a diverse group of mammals with unique physical adaptations that allow them to thrive in the marine environment with extreme temperatures, depths, pressure, and darkness. Marine mammals are classified into four different taxonomic groups: cetaceans (whales, dolphins, and porpoises), pinnipeds (seals, sea lions, and walruses), sirenians (manatees and dugongs), and marine fissipeds (polar bears and sea otters).

Sea turtles breathe air, like all reptiles, and have streamlined bodies with large flippers. They are well adapted to life in the ocean and inhabit tropical and subtropical ocean waters around the world. Of the seven species of sea turtles, six are found in U.S. waters; these include the green, hawksbill, Kemp's ridley, leatherback, loggerhead, and olive ridley.

104 Marine Life Essay Topic Ideas & Examples

🏆 best marine life topic ideas & essay examples, 👍 good essay topics on marine life, ⭐ simple & easy marine life essay titles.

• Ocean Pollution and the Fishing Industry In essence, the activities of over six billion people in the world are threatening the survival and quality of water found in the oceans, lakes and other inland water catchment areas.
• The Aral Sea Problems, Their Causes and Consequences To identify and analyze the problems of the lake, its basin, and the entire region To discuss the causes and consequences of the lake’s destruction To evaluate the solutions proposed for ameliorating the consequences The […]
• Climate Change Impacts on Ocean Life The destruction of the ozone layer has led to the exposure of the earth to harmful radiation from the sun. The rising temperatures in the oceans hinder the upward flow of nutrients from the seabed […]
• Marine Parks Concept Overview In terms of marine tourism, aquatic parks offer the best solution for tourists because they are cheaper than watching animals in the sea.
• The Impacts of Oil Spills on Marine Life The intensity of aquatic effects is influenced by the nature and extent of the spilt oil. Besides, the severity might be influenced by the sensitivity and ambient state of the pretentious marine and their surroundings […]
• Life in the Bottom of the Ocean and Its Protection While we all strive hard to detect and analyze the essence of life and the impact it has on our lives, we need to understand that life in itself is a big mystery, the truth […]
• Plastic Waste and Its Effects on Marine Life However, many people do not appreciate the importance of oceans to human and marine life. Another effect of microplastics on the marine community is that they lead to uneven distribution of organisms.
• Living Resources of the Ocean The most commendable among the benefits of marine life to human life are the fact that marine life can act as food and the fact that some oceanic organisms have medicinal value.
• The Indian Ocean Tsunami of 2004 and Its Consequences The worst effects of the great wave were observed in Indonesia, where the death toll exceeded 160,000 people, and the overall damages almost reached $4.
• Marine Life in United Arab Emirates This report analyses the marine life in the UAE, covering detailed information about the various species of animals found in the region and their adaptation to the unique environment.
• Plastic Ocean Pollution on Ocean Life in U.S. Ocean plastic pollution has had a great impact on a minimum of two hundred and sixty seven species across the world and these include forty three percent of all of the sea mammal species, eighty […]
• The Ocean Pollution Problem Overview Ocean pollution is the unfavorable upshot due to the entrance of chemicals and particulate substances into the ocean. The land is the key source of ocean pollution in the form of non-point water pollution.
• Marine Biology: Polar Oceans as an Eco System The water in and around the Antarctic continent is referred to as the Antarctic or Southern Ocean. The Atlantic Water is situated between the Arctic Surface Water and the Arctic Deep Water.
• Habitat and Ocean Life Considerations of Bottlenose Dolphins The temperate and tropical oceans of the world are home to bottlenose dolphins. On the American continent, bottlenose dolphins can be seen along California’s southern beaches and the eastern seaboard from Massachusetts to Florida, and […]
• The Aral Sea’s Environmental Issues Prior to its destruction, the Sea was one of the biggest water bodies, rich in different species of flora and fauna; a case that is opposite today, as the sea is almost becoming extinct.
• Ocean Fisheries Sustainability Analysis It is necessary for fishing industries to use better fishing methods in the ocean to ensure that their activities do not endanger the ecological balance. Fish species do not get the chance to replenish and […]
• Sea Foods in the Environment Protection Context Further, the purpose of the website is to give information that seeks to reward the efforts of people who protect and safeguard the ocean and seafood supplies such as lobsters.
• “History of Ocean Basins” by Hess From the article it is vivid that the coming into being of oceans is subject to discussion since the previous knowledge is doubtful, and the existing framework is confusing.
• Marine Biodiversity Conservation and Impure Public Goods The fact that the issue concerning the global marine biodiversity and the effects that impure public goods may possibly have on these rates can lead to the development of a range of externalities that should […]
• Marine Ecosystems in Oceanography Studies While oceanography students need to understand these aspects of ocean management, this paper focused on marine ecosystems, as a broad and useful topic in oceanography studies.
• The Problem of Ocean Pollution in Modern World Wastes such as toxic matter, plastics, and human wastes are some of the major sources of pollution in the ocean. Many people consume fish as food; when marine life is affected by toxic substance in […]
• How Deep Sea Discoveries Inspires Professional Creativity Limited technological access to the deep seas should inspire one to focus on the necessary technology to build the most efficient deep-sea robots.
• Marine Environment Protection and Management in the Shipping Industry Therefore, criminal penalties system in collaboration with the Environmental Protection Agency should reinforce legislations to protect sea creatures and humans from oil pollution or wastes from ships.
• Marine Creatures and Terrestrial Animals in “The Wild West: Gold Rush” In fact, Californian nature is rich in various animal species that live to survive and pass their genes to the offspring.
• Effect of Sea Water and Corrosion on Concrete On the other hand, substantial tautness, for instance due to meandering will shatter the tiny firm pattern, ending up in fracturing and disjointing of the concrete.
• How the Ocean Current Affect Animals’ Life in the Sea Depending on the strength of the ocean current, sea animals along the path are flown along with the water, and the animals are moved to new regions that are sometimes thousands of kilometers away causing […]
• The Dead Sea Geochemical History Globally, the most saline location is found on the water surfaces and shores of the Dead Sea. On the other hand, the pattern of fluctuation in temperature and salinity in the Arctic Ocean is complex.
• The Ocean’s Rarest Mammal Vaquita – An Endangered Species The vaquita looks like a curved stocky porpoise, and it is the smallest of all the porpoises in the world. This is a matter of concern and ought to be investigated if the survival of […]
• Sea Otters’ Life Cycle From Birth to Death However, after the species had almost become extinct and their protection began, the species began to recover and towards the close of the 20th century, conservation had given rise to tens of thousands of sea […]
• The Negatives of Fossil Fuel: Ocean Acidification and Human Health The adverse effects of burning oil are hard to overestimate. Unless specific and practical actions are taken to address the issues of global climate change and pollution issues and reduce reliance on oil, the future […]
• Impacts of Climate Change on Ocean The development of phytoplankton is sensitive to the temperature of the ocean. Some marine life is leaving the ocean due to the rising water temperature.
• Exploring Environmental Issues: Marine Ecotourism For marine ecotourism to succeed, it must thrive in a manner that accommodates the needs of both the current and future generations and safeguards the natural environment.
• Autonomous Platforms in Marine Research One of the significant ideas that can increase the overall efficiency of the data collection process is the creation of networks of autonomous platforms.
• The Sea Water Impact on the Human Cell Hence, consuming it causes a high amount of salt without the human cell, which leads to a steep concentration gradient within the cell, thereby causing water to be drawn out, which is detrimental to the […]
• Ocean Sustainability and Human Economic Activity The world economy and the livelihoods of hundreds of millions of people depend on the ocean. It is important to remember that the misuse of water resources and the effects of global climate change will […]
• Integrated Coastal Zone Management in the Red Sea and the Gulf of Aden The role of the ICZM in the control of environmental, transport, industrial, and other types of safety is high, and the example of the RSGA region proves this.
• Mining and Ocean Use in Canada Cobalt, nickel, manganese, and copper are among the metals deep seabed mining seeks to extract from the polymetallic nodules on the seafloor and seamounts.
• Addressing Marine Debris: Causes, Effects, and Potential Solutions A major limitation that makes the eradication of the problem difficult is the fact that most of the debris contains microplastic.
• Visiting San Francisco Bay as Marine Protected Area San Francisco Bay Bridge will become the central place for this trip because it is just in the center of this view.
• Non-trophic Interaction in Marine Species An example of non-trophic relationships between marine species is decorator crabs and sponges. Decorator crabs and sponges’ relations are an example of mutually helpful non-trophic interaction mutualism.
• The Rising of Sea Level and Melting Glaciers: Analysis of the Issues In modern realities, the rate of warming of the World’s Oceans has increased. Global warming provokes the melting of ice in Greenland and Antarctica.
• Ocean Dumping Issue and Rhetorical Rationale Therefore, the goal of this paper is to prove that the poster in question manages to accomplish an impressive goal of subverting the audience’s expectation and encouraging them to shift from an ironic perception of […]
• The Ocean Dumping Problem: A Visual Argument There is, however, less awareness of deep-sea drilling and the impacts on the habitat and human life in the oceans and along the coasts.
• Australia’s Endangered Diverse Marine Ecosystem Climate Change and population increase are becoming increasingly difficult to perceive distinctly, especially when the question is about the loss of a diverse marine environment.
• Integrated Ocean Drilling Program Expedition 342 Such flows reduce the temperature of the planet’s core, change the composition of the foundation bedrock, and impact microorganism dispersion in the subterranean ecosystem.
• Ocean Circulation and Biogeography, Species Distribution, Invasive Species The concept of ocean circulation refers to the movements of water in the oceans and seas. Surface ocean currents carry water from the poles to the tropics, where it is heated, and, afterwards, this water […]
• Plastic Ocean and Its Effect on the Ecosystem The purpose of this essay is to present science-based facts in support of the author’s words to convince the reader of the criticality of the ecological problem.
• Marine Protected Areas: Impact on Kelp Forest Recovery and Urchin Reduction The research aims to study the effectiveness of MPA for kelp forest recovery and urchin reduction. The research aims to study the effectiveness of MPA for kelp forest recovery and urchin reduction.
• Environmental Marine Ecosystems: Biological Invasions One of the biggest hypoxic zones in the US is in the Gulf of Mexico. The condition of water in the area caused the decline of the shrimp industry.
• Effects of Global Warming on Marine Life Global warming has adverse effects on the marine life. It has led to the extinction of some of the animals and living things and has been necessitated by human activities.
• Deep-Sea Biology: The Search for a Sea Monster This case study is about the attempts of Clyde Roper to find the giant squid. This canyon is known to be very deep and runs towards the Kermadec Trench which is also documented to be […]
• Bacterial Diseases of Marine Organisms The striped dolphin is a highly susceptible host of the bacteria and poses and the most potent reservoir and source of transmission of the infectious agent.
• Ecotoxicology in the Marmara Sea: A Critical Review The importance and actuality of the paper can not be exaggerated, as the problem of toxic wastes is one of the most burning in Europe.
• Marine Surveying, Inspection and Safety Practices The importance of these conventions and rules was to address the need to access different ports in different countries based on uniform rules and standards acceptable to destination ports or countries in addition to maintaining […]
• How Climate Change Impacts Ocean Temperature and Marine Life The ocean’s surface consumes the excess heat from the air, which leads to significant issues in all of the planet’s ecosystems.
• Dell’s Initiative to Recycle Ocean-Bound Plastics The innovation to use plastics from the ocean and areas where these materials had a high risk of moving to the water was presented to the company in 2015.
• High Seas Marine Protected Areas: Effective Legislation or Paper Parks This essay dwells on the definition and importance of MPAs, including the ones in the high sea. The goal of the alliance is to bolster international collaboration and exchange of knowledge.
• Intergovernmental Relations and Ocean Policy Change The administration of Ronald Reagan contributed to the Federal ocean policy in the 1980s. During this change, analysts believed the United States was making a shift from ocean protection of the 1970s to ocean management […]
• Improving the Response to Marine Emergencies However, we still need to facilitate this process, for instance, by informing the National Fire Service about the implementation of this project and its results. These are the most objectives that have to be attained […]
• A Benchmarking Biodiversity Survey of the Inter-Tidal Zone at Goat Island Bay, Leigh Marine Laboratory Within each quadrant, the common species were counted or, in the case of seaweed and moss, proliferation estimated as a percentage of the quadrant occupied.
• Ocean Circulation in a Warming Climate These effects will enhance the development of reduced release of radio-carbon depleted carbon dioxide gas and thus the idea of the self-restoration mechanism of the earth to this global warming.
• Protected Marine Areas: Great Barrier Reef To protect the Great Barrier Reef the administration has put in place several policies to protect this region. In this plan, A panel of scientists was to advise on the quality of waste.
• Ocean Thermal Energy Conversion The warm seawater is carried into a chamber and is used to produce vapor that, in turn, is used to rotate a turbine.
• Review of the Quaternary History of Reefs in the Red Sea With Reference to Past Sea-Level Changes Some of the changes have occurred on the very grandest of scales, such as the Merging and ensuing breaking up of huge supercontinents, or the decimation of the dinosaurs by extra-terrestrial impacts.reefs are not invulnerable […]
• Radiocarbon C14 Dating in Marine Geology The radiocarbon technique can say to be one of the most important inventions of the 20th century, especially in the field of human science.
• Marine Pollution: Sources, Types, Pathways, and Status By examining sources, types, pathways, and status of water contamination in the context of the World Ocean, it is clear that most marine pollution caused by human actions, especially the mismanagement of plastic debris.
• Concerns of Ocean Ecosystem Pollution The range of adverse outcomes for ocean ecosystems can be discussed in volumes; however, the current discussion will focus on trash in the ocean waters, acidification, and the disruption of the marine life cycles.
• Marine Degradation and Solutions in the Pacific Region The second issue related to the degradation of marine resources in the Pacific region is the unsustainable use of marine resources, including destructive fishing, which leads to changes in the number and health of species.
• Port Philip Bay and Sea Levels in Australia’s Geological History As the scientist explains, the phenomenon of the port’s emergence in the dry environment can be attributed to the fact that considerable water shrinkage could be observed in the area roughly 1,000 years ago.
• Geology: Port Phillip Bay and Sea Level Changes Specifically, the fossils of specific creatures, such as the shells of tertiary foraminifera, as well as the meanders of the river channels, which were located in the area, are bound to bolster the hypothesis suggested […]
• Marine Algae Associated Bacteria as Antioxidants The antinociceptive activity analysis involved comparing the reaction time of mice treated with the extracts and the controls. The authors conclude that the isolation and characterization of the bioactive principles from the potent strains could […]
• Ocean-Plate Tectonics and Geology Bathymetry of the ocean seafloor refers to the measurement of how deep the sea is in relation to the sea level.
• Impact of Sea Transport on the Aquatic Environment The shipping companies also have a serious impact on the maritime environment in terms of the wastes often released into the water.
• Deep-Sea Currents and Upwelling Along Florida The thermohaline circulation influences the movement and population of the marine ecosystem and heat redistribution both in the sea and on the earth’s surface.
• Climate Change Effects on Ocean Acidification The scientists realized that the crisis lasted for several millennia before the oceans could fully recover from the impacts of the drop in the pH level.
• Marine Geology, Hydrology and Human Impact on Earth However, the implementation of the new technologies and practices in the process of investigation of the sea depths resulted in the appearance of the new meaning.
• Marine Ecosystems, Human Dependence and Impact The growth of communities dependent on fishing is proportional to the destruction of marine ecosystems. The survival of the human race, and the survival of millions of species of wildlife is dependent on a healthy […]
• The Northern Sea Route’ Safety Management The company discusses the opportunity to trade some of the vessels with the help of the NSR. The NSR is discussed as an attractive option to decrease the time spent in the voyage while comparing […]
• Water Crisis, Oceans and Sea Turtles Issues In the case of Mexico, it appears that the past regimes have never put a lot of focus on the utilization of water resources.
• SOFAR Effects on the Marine Life The speed and energy of the sounds that are transmitted in the SOFAR channel are maintained without being altered because of the pressure, which increases with increase in depth.
• Ocean Acidification Impact on the Sea Urchin Larval Growth Due to the carbon dioxide increase in the atmosphere, acidity in the oceans is increasing++ and a fast increase of change rate is experienced.
• Deep Sea Mining: Salt Extraction This therefore shows how important the process of evaporation is in regard to extraction of salt from the sea. This therefore explains that sea water is a cheap source of salt in terms of time […]
• Pacific Ocean: Essentials of Oceanography The ocean has about 25,000 islands which are in excess of the entire number islands in all the oceans across the world. The volume of water in the ocean is about 622 million km3.
• El Niño’s Effects on Marine Life El Nino makes the winds of the east blow to the west and moves the layers of warm water in the Pacific Ocean.
• Ecology Issues: Creatures of the Deep Sea Discuss the negative changes that are occurring and the cause of these changes In the recent past, the temperature on the earth has been rising steadily due to the effect of global warming.
• Ocean Literacy and Exploration From the onset of “human-ocean interaction and exploration in the fifteenth century” and despite ocean being the largest feature of the earth, only 5% of the ocean is known.
• Ocean and Atmosphere Circulation Oceanic and atmospheric circulation is the means by which heat is distributed on the surface of the Earth by large scale circulation of air.
• The Role of Sea Power in International Trade The historical influence that the marines or the navy has had on international trade and the complications in comparing measures of sea power has been issues of discussion in the past.
• The Global Ocean Conveyor Belt This ocean water phenomenon is a result of the temperature difference in the ocean waters between the warm, salty surface water, and the less salty cold water in the ocean depths.
• Florida Keys National Marine Sanctuary Reefs This essay addresses some of the disturbances which have been experienced in the coral reefs of the Florida Keys National Marine Sanctuary together with measures which have been implemented to salvage the ecosystem.
• Marine Conservation and Coastal Development The committee should comprise of a balanced membership for holistic review of the coastal development projects. The lack of legislation related to marine conservation is also a major setback.
• Impact of the Toxic Substances on Marine Ecosystem The condition of hypoxia is created when algal biomass decompose leading to dissolution of oxygen in the water column. While, on the other hand, farming of Bluefin tuna leads to destruction of marine life as […]
• Climate Shift Could Leave Some Marine Species Homeless This is very important as it helps put pressure on countries to reduce on carbon release, in order to conserve the environment and hence species at risk.
• Global Warming Outcomes and Sea-Level Changes The outcome of global warming has been exhibited by the melting of ice and snows in areas such as the Antarctic which has changed the average sea level of the whole world because the ice […]
• Deep Sea Volcanoes and their Effects Deep sea volcanoes are present under deep sea ridges of the ocean floor and the above research has been based on the amount of carbon dioxide that is present in depths of four kilometers on […]
• Policy Change to Control Ocean Dumping Policies addressing the issue of ocean dumping and the need to curb it have been in place. Several factors fueled the change; for instance, change in the information concerning the effect of ocean dumping to […]
• Coral Reef Essay Topics
• Hunting Questions
• Moby Dick Questions
• Landfill Essay Titles
• Pollution Essay Ideas
• Tsunami Essay Ideas
• Biodiversity Research Topics
• Fishing Research Topics
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What Is Marine Life And Its Importance? Facts & Statistics

Reading time: 8 minutes

The Earth’s oceans are home to millions of animal and plant species, as well as potentially millions more that are so far undiscovered. They are delicately balanced ecosystems and their healthy function is key to the balance of all life on Earth. Many people see marine life as something altogether separate to life on land but the two are far more connected than we might think. Crucially, the behavior and choices made by people seriously impact the wellbeing of our aquatic friends.

What Is Marine Life?

Marine life refers to all the animals, plants and organisms that live in Earth’s saltwater seas and oceans. From the smallest plankton to the largest whale, all organisms play a role in the healthy function of these amazing, complex ecosystems.

Coral Reef Ecosystems

Coral reefs are diverse, colorful and home to millions of marine species across the planet. They provide a natural barrier to the power of the ocean, protecting coastal communities from extreme weather events such as tsunamis. As food chains, they are extremely important, providing an area in which marine species can live, feed, raise their young and thrive.

Unfortunately, they are also highly vulnerable to ocean temperature change, a direct result of climate breakdown. In 2016, Australia’s Great Barrier Reef experienced a 30 percent loss of coral reef due to a nine-month marine heatwave, the largest reef loss ever recorded. The fishing of reefs has also led to species loss, as food chains are interrupted and predators cannot survive.

Some examples of the largest reef ecosystems on earth include:

• The Great Barrier Reef, Australia
• The Red Sea Reef, Egypt, Sudan and Eritrea
• New Caledonia Barrier Reef, southwest Pacific Ocean
• Florida Reef, USA
• Andros Coral Reef, the Bahamas

Ocean Fishes

There are thousands of different species of ocean fish, yet populations are continually declining as we allow commercial fleets to fish our oceans. Atlantic cod, for example, can live up to 25 years, yet their populations are now at critically low levels. Some other ocean fish include:

• Barramundis

Marine Mammals

Marine mammals are generally larger sea creatures, who live underwater but need to breathe air also. Around the world these marine mammals still lose their lives unnecessarily due to habitat loss, being caught and killed by fishing fleets (“ fishing bycatch ”), hunting and noise pollution.

• Marine mammals include:

Sea Turtles And Reptiles

Reptile life in the sea is largely made up of turtle species such as:

• Loggerhead turtles
• Hawksbill sea turtles
• Green sea turtles
• Leatherback sea turtles

All seven species of sea turtles are endangered or critically endangered with The World Wildlife Fund stating that “the single biggest threat to most sea turtles is fishing gear.”

Marine iguanas and saltwater crocodiles are also ocean-dwelling species of reptile. Reptilian life in the sea is particularly vulnerable to pollutants such as plastic, as these animals live in shallow seas and come into contact with human populations often.

Cephalopods, Crustaceans And Shellfish

Cephalopods, crustaceans and shellfish play an important role in ocean ecosystems and the marine food chains, and includes:

• Cuttlefishes

They are particularly vulnerable to increased ocean acidification, a direct result of increased human-generated greenhouse gas emissions.

Seabirds are found on coastlines, in coastal waters and far out at sea, and include species such as:

• Albatrosses
• Fish eagles

Seabirds play a vital role in marine ecosystems but populations have dropped by 70 percent since the middle of the 20th century, with campaigners saying that they are being pushed to the brink of extinction by the fishing industry. Habitat destruction and pollution also play a part.

Why Marine Life Is Important?

The oceans provide 50 percent of the world’s oxygen and they provide essential ecosystem services that allow our planet to function in a healthy way. For example, ocean currents govern our weather systems, and if they were to be interrupted, the extreme weather consequences would be drastic. The oceans can only provide these services by maintaining delicately balanced ecosystems, made up of food chains and biological systems. Human activity risks the shutdown of essential ecosystem services that we rely on to survive.

One example is coral reefs. When we fish around coral reefs, those reefs’ delicate ecosystems are damaged and often die. We then lose the essential service a coral reef provides such as protection from erosion and weather, biochemical regulation, and recreation. This is just one of the reasons why taking care of the oceans is essential for our own wellbeing.

Marine Life Facts And Statistics

• An estimated 50-70 percent of all life on Earth is found under the oceans
• Humans have explored roughly 10-20 percent of the ocean
• There are around 230,000 classified marine species, but as many as two million or more yet to be discovered
• Marine biodiversity is declining at an alarming rate. It is estimated the oceans suffered around a 50 percent species loss between 1970 and 2012

Marine Life Pollution

Humans continue to pollute the oceans, despite the huge risks to marine life and to ourselves. Marine pollution comes in many forms such as plastic pollution, acidification and oil spills.

How Does Ocean Acidification Affect Marine Life?

Ocean acidification occurs due to increases in carbon dioxide in the atmosphere (due to climate warming) and it can have terrible consequences for marine life, particularly crustaceans. Higher acidity in water results in shells dissolving more quickly, which of course has a devastating impact on shellfish and other crustaceans. This can have drastic knock-on consequences for other animals who rely on them for food, and throw marine food chains and whole ecosystems out of balance..

How Do Fisheries And Seafood Affect Marine Life?

Probably the largest risk posed to marine life is the fishing industry. Vast commercial fleets trawling the oceans has been common practice for many years and sadly shows no signs of slowing. The negative impacts for marine life are huge and includes:

• Fish population crashes which impacts every species that live in the oceans. Bycatch from fishing nets results in huge biodiversity loss, including driving species to the brink of extinction.
• There is evidence to show that catching fish causes pain and is hugely distressing for those caught and those left behind.

How Does Fish Farming Affect Marine Life?

Fish farming poses various environmental and welfare risks including:

• Disease is easily spread in fish farms and too often spreads beyond the farm into the natural environment.
• Fish farms pollute waters with the chemicals needed to treat diseases caused by the appalling conditions, excess feed and concentrated fish waste. This pollution causes algal blooms, resulting in the deaths of wild fish, too.
• Wild marine animals, such as seals, are inevitably attracted to fish farms as a potential source of food, but these animals are often killed deliberately by farmers to stop them eating the valuable fish.

How Does Human-generated Noise Pollution Affect Marine Life?

Natural soundscapes in the ocean are key for healthy marine life, as animals use sound to communicate, catch food, navigate, defend themselves and attract mates. Machinery like boats, jet skis or oil drills create an unnatural barrier to marine life’s natural soundscape, and the impacts can devastating:

• Marine mammals like whales use complex songs to communicate, navigate and attract one another. If these are interrupted, they cannot enact basic natural functions and die as a consequence
• Animals can be directly stressed by unnatural noise, leading them to make poor decisions that can lead to their deaths

Other Forms Of Pollution?

Plastic pollution is the other major form of marine pollution that affects marine life:

• Plastic waste can entrap marine animals resulting in them drowning, starving or being eaten
• Soft plastics and microplastics can be ingested by marine life and cause their deaths
• Plastic pollution kills 100 million marine mammals and up to a million seabirds every year
• Most plastic pollution comes from the fishing industry

How Can We Save Marine Life?

Put simply, we can save marine life by leaving the oceans alone and letting their ecosystems operate naturally. These systems have developed over millions of years of evolution and they can only operate without our intrusion.

We can reduce our impact on marine life in a few ways:

• Go vegan. Stopping consumption of marine animals is the single biggest way to help the oceans. It would stop overfishing and bycatch, returning fish populations to healthy levels. It would also reduce noise pollution from fishing vessels, reduce oil spills and plastic pollution from fishing fleets, and lower carbon dioxide levels, thereby reducing ocean acidification
• Reduce our consumption of all unnecessary products and buy local as much as we can – global shipping networks create noise and chemical pollution in the oceans, which directly affects marine life
• Reduce our reliance on plastics, stop buying single-use plastic items, and recycle plastic waste effectively, so that it never ends up in the ocean
• Raise awareness of the issues – watch and share documentaries such as Seaspiracy to alert others of the need to save marine life

Healthy marine life is critical to the healthy function of the whole planet and to the lives of all those who inhabit it. Without healthy balanced oceans, many of our essential ecosystem services would collapse, resulting in terrible knock-on effects for humans and animals alike. But that is not the only reason to protect marine life. We should protect them for their own sake. The lives of marine animals are as important to them as ours are to us. They are here on Earth with us, not for us.

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The Ocean: Life Below Water and Why it Matters

Key questions >>>

• Why does the ocean matter? How is the ocean important for sustainable development?
• What does the sustainable blue economy offer us?
• What are the ocean knowledge gaps?
• How do we need to develop a multidisciplinary ocean science?

The ocean covers around three-quarters of the earth's surface and contains more than 90% of living species on our planet. The ocean is also the single largest ecosystem in the world, and it provides food for billions of people worldwide, as well as maritime transport, renewable energies, and other goods and services like regulating, cultural and supporting services. 

Nevertheless, the ocean is not indestructible, and our footprint is very large. Overfishing, toxic pollution, invasive species, nutrient over-enrichment, habitat degradation and destruction, biodiversity loss, dependence of a growing global population on its goods and services, and coastal development, all threaten the sustainability of coastal ocean ecosystems ( Vanderweerd in Sherman and McGovern, 2011). Ocean acidification is also a growing threat that may be more important than warming, pollution and overfishing (Roberts, 2011).

Why Does the Ocean Matter?

Oceans mean different things for different people: life, passion or wonderment; vastly important; a very important source of life and energy; an incredible source of food and amazing source of biodiversity; it's wild, exciting, terrifying and exhilarating; means a lot to me, if something happens I will not have the fun I’m used to; it's a livelihood, it's been there for generations and hopefully will be there for generations to come.’ (Adapted from video excerpt, Plymouth Marine Laboratory, 2011, in Muñoz-Sevilla and Le Bail 2017).

According to the World Wildlife Fund, the ocean is currently valued at $24 trillion dollars. The goods and services from marine environments add up to an additional $2.5 trillion yearly. This means the ocean would have the seventh-largest GDP in the world.  However, the value of the ocean relies on its current output, which in turn depends on its conditions. Climate change, ocean acidification, habitat destruction, pollution and overfishing are endangering the ocean and threatening its value and the security and livelihood of the three billion people who depend on it. Most of these people live in Small Island Developing States, they are among the ones who contribute least to these issues, but they are the ones at most risk, as they’re already vulnerable. ( Hoegh-Guldberg 2015)

Agenda 2030: SDG 13 and SDG 14

A historical change has been taking place for the past 23 years, from Agenda 21 to Agenda 2030. At the Rio de Janeiro Earth Summit in 1992, more than 178 countries adopted Agenda 21. The Millennium declaration was adopted after the 2000 Millennium Summit in New York. 10 years after the Rio Earth Summit, in the Millennium Development Goals (MDGs) that were adopted during the Earth Summit in Johannesburg, ocean issues were included in the conversation for the first time. 

In 2012, at the United Nations Conference on Sustainable Development (also popularly known as Rio+20), member states adopted the document titled “The Future We Want”, which set the process of developing the sustainable development goals (SDGs) building on the MDGs. Finally, during the UN Sustainable Development Summit in 2015, seventeen SDGs were adopted which are an integral part of the 2030 Agenda.  

Progress of SDG 14 in 2019

The expansion of protected areas for marine biodiversity and existing policies and treaties that encourage responsible use of ocean resources are still insufficient to combat the adverse effects of overfishing, growing ocean acidification and worsening coastal eutrophication. As billions of people depend on oceans for their livelihood and food source, increased efforts and interventions are needed to conserve and sustainably use ocean resources at all levels. 

• Ocean acidification is caused by the uptake of atmospheric CO 2 by the ocean, which changes the chemical composition of the seawater. Long-term observations over the past 30 years have shown an average increase of acidity of 26 percent since pre-industrial times. At this rate, an increase of 100 to 150 percent is predicted by the end of the century, with serious consequences for marine life. 
• To achieve sustainable development of fisheries, fish stocks must be maintained at a biologically sustainable level. Analysis reveals that the fraction of world marine fish stocks that are within biologically sustainable levels declined from 90 percent in 1974 to 66.9 percent in 2015. 
• As of December 2018, over 24 million km 2 (17.2 per cent) of waters under national jurisdiction (0–200 nautical miles from a national border) were covered by protected areas, a significant increase from 12 percent in 2015 and more than double the extent covered in 2010. The protected areas increased from 31.2 per cent in 2000 to 44.7 per cent in 2015 and to 45.7 per cent in 2018. 
• Illegal, unreported and unregulated fishing remains one of the greatest threats to sustainable fisheries, the livelihoods of those who depend upon them and marine ecosystems. Most countries have taken measures to combat such fishing and have adopted an increasing number of fisheries management instruments in the past decade. 
• Small-scale fisheries are present in almost all countries, accounting for more than half of total production on average, in terms of both quantity and value. To promote small-scale fishers’ access to productive resources, services and markets, most countries have developed targeted regulatory and institutional frameworks. However, more than 20 per cent of countries have a low to medium level of implementation of such frameworks, particularly in Oceania and Central and South Asia.

The Ocean Decade

To recognize that more needs to be done to mitigate the global decline in ocean health, in December 2017, the UN declared 2021 to 2030 as the decade of ‘Ocean Science and Sustainable Development’. 

The Ocean Decade will strengthen international cooperation in all levels by strengthening dialogues, developing partnerships, developing capacity-building and leveraging investment, while supporting the entire 2030 Agenda for sustainable development. Other critical goals include improving ocean literacy and education to modify social norms and behaviors, and creating new models for ocean action.

The Ocean Decade aims to include science-informed mitigation and adaptation policies around the world and share knowledge with coastal communities who are most vulnerable to the changes of the ocean. (Claudet et al. 2019)

The COVID-19 Pandemic and the Ocean 

From Little Blue Letter, Glen Wright

• Marine creatures are enjoying some quiet time as underwater noise levels drop. Scientists are studying these effects on marine mammals.
• ​From Florida to Thailand, the number of sea turtles nests has increased on the now-empty beaches. The rapid recovery of marine wildlife in coastal areas shows how extensive our impacts are and highlights the importance of protected areas. 
• Fishers around the world are struggling with decreased demand, lack of sanitary conditions and logistical challenges. In some countries, like India, food security of the communities may be affected by this disruption of supply chains.
• PADI and Rash’R are producing (non-profit)  reusable face masks made from Ocean plastic , with designs based on sea animals!

Final Remarks

We can all take small steps towards protecting our ocean. Reduction of single-use plastic, responsible fish consumption, avoiding ocean harming products, and making your voice heard can all directly contribute towards a healthier ocean. However, more indirect approaches can be taken by reducing the amount of greenhouse gases produced by our daily activities and, therefore, reducing our carbon footprint. Reducing red meat consumption, consuming locally sourced products and using personal vehicles less are all examples of small steps we can take towards reducing our impact. The sum of individual actions can truly make a difference in the fate of our ocean.

Collectively, we need to form a global ocean community, acknowledging that all of our actions have an impact on the ocean (Claudet et al. 2019). And, although it is incumbent on each of us to take steps to protect the ocean, collective action is also required. New models for ocean action, which are collaborative, intergenerational, cross-cultural, and multi-sectoral, are needed in the coming decade, in order to protect our beloved ocean. 

The ocean is our life support system, it connects every one of us, you can think of the ocean as the blue heart  of this planet, but then we look after that heart and we know how we are damaging it and it needs intensive care. We know that scientists, politicians and stakeholders are talking to each other, but it isn’t just up to them, each and every one of us can make the difference, even if the difference might be small, after all individual small drops of sea water can make up the vast ocean . (Adapted from video excerpt, Plymouth Marine Laboratory 2011, in Muñoz-Sevilla and Le Bail 2017).

Bibliography

Cheung, W. et al (2013), “Signature of Ocean Warming in Global Fisheries Catch”, Nature, 497(2013): 365–368.

Claudet, J. et al (2019), “A Roadmap for Using the UN Decade of Ocean Science for Sustainable Development in Support of Science, Policy, and Action”, One Earth , 2(1): 34-42.

Halpern, B. et al (2012), “An Index to Assess the Health and Benefits of the Global Ocean, Nature , 488(2012): 615–620.

UNESCO and UNEP (United Nations Educational, Scientific and Cultural Organization and United Nations Environment Programme) (2016), Large Marine Ecosystems: Status and Trends, Summary for Policy Makers , Nairobi: UNEP.

Muñoz-Sevilla N. and M. Le Bail M (2017), “Latin American and Caribbean Regional Perspectives on Ecosystem Based Management (EBM) of Large Marine Ecosystems Goods and Services”, Environmental Development , 22(2017), 9-17.

Munoz-Sevilla N. et al (2019), UNU Ocean Institute Scoping Study Report , Tokyo: United Nations University.

Plymouth Marine Laboratory (2011), Ocean Acidification: Connecting Science, Industry, Policy and Public (A Short Film for the Natural Environment Research Council and the UK Ocean Acidification Research Programme), Plymouth Marine Laboratory

Roberts D. (2011), In: Ocean Acidification: Connecting Science, Industry, Policy and Public . A short film for the Natural Environment Research Council and the UK Ocean Acidification Research Programme. Plymouth Marine Laboratory.

Sherman, K. and G. McGovern (2011), Toward Recovery and Sustainability of the World’s Large Marine Ecosystems during Climate Change , Gland, Switzerland: International Union for Conservation of Nature.

Sherman K. et al (2017), “Sustainable Development of Latin American and the Caribbean Large Marine Ecosystems”, Environmental Development , 22(2017), 1-8.

United Nations (2015), Transforming Our World: the 2030 Agenda for Sustainable Development , New York: UN.

Wright G. (2020), “The Pandemic and the Ocean”, Email Correspondence on May 1, 2020.

Hoegh-Guldberg, O. (2015), Reviving the Ocean Economy: The Case for Action , Geneva: World Wide Fund for Nature.

Consulted on April 24th, 2020. (2019) What is the United Nations Decade of Ocean Science for Sustainable Development?. https://www.oceandecade.org/about?tab=our-story . Consulted on May 4th, 2020.

Introductory essay

Written by the educators who created The Deep Ocean, a brief look at the key facts, tough questions and big ideas in their field. Begin this TED Study with a fascinating read that gives context and clarity to the material.

How inappropriate to call this planet Earth when it is quite clearly Ocean. Arthur C. Clarke

Planet Ocean

In the late 1960s, the Apollo Mission captured images of Earth from space for the very first time. These iconic photos gave people around the world a fresh perspective on our home planet — more specifically, its vast and dazzling expanses of blue. It's perhaps unsurprising that science has subsequently established the key roles that the ocean and its marine organisms play in maintaining a planetary environment suitable for life.

While the Apollo astronauts were sending back pictures of our blue planet, a scientist at the Jet Propulsion Laboratory in California was searching for ways to detect life on other planets such as Mars. James Lovelock's investigations led him to conclude that the only way to explain the atmospheric composition of Earth was that life was manipulating it on a daily basis. In various publications, including his seminal 1979 book Gaia: A New Look at Life on Earth , Lovelock launched the Gaia hypothesis, which describes how the physical and living components of the natural environment, including humankind, interact to maintain conditions on Earth. During the same period, marine scientists including Lawrence Pomeroy, Farooq Azam and Hugh Ducklow were establishing a firm link between the major biogeochemical cycles in the oceans and marine food webs, particularly their microbial components. In the late 1980s and 1990s, large-scale research programs like the Joint Global Ocean Flux Study (JGOFS) explored ocean biogeochemistry and established the oceans' pivotal role in the Earth's carbon cycle.

Research efforts like these underscored the oceans' critical importance in regulating all the major nutrient cycles on Earth. It's now widely recognized that the ocean regulates the temperature of Earth, controls its weather, provides us with oxygen, food and building materials, and even recycles our waste.

The advent of deep-sea science

It seems remarkable that until fairly recently many scientists believed that life was absent in the deep sea. Dredging in the Aegean Sea in the 1840s, marine biologist Edward Forbes found that the abundance of animals declined precipitously with depth. By extrapolation he concluded that the ocean would be azoic (devoid of animal life) below 300 fathoms (~550m depth). Despite evidence to the contrary, scientists supported the azoic hypothesis, reasoning that conditions were so hostile in the deep ocean that life simply could not survive. Extreme pressure, the absence of light and the lack of food were viewed as forming an impenetrable barrier to the survival of deep-sea marine species.

But others were already proving this hypothesis wrong. As Edward Forbes published his results from the Aegean, Captain James Clark Ross and the famous naturalist John Dalton Hooker were exploring the Antarctic in the Royal Navy vessels HMS Terror and HMS Erebus . During this expedition, Ross and Hooker retrieved organisms from sounding leads at depths of up to 1.8km, including urchin spines and other fragments of various marine invertebrates, a number of bryozoans and corals. Ross remarked, "I have no doubt that from however great a depth we may be enabled to bring up the mud and stones of the bed of the ocean we shall find them teeming with animal life." This contention was supported by work of Norwegian marine biologists Michael Sars and George Ossian Sars who dredged hundreds of species from depths of 200 to 300 fathoms off the Norwegian coast.

Further evidence came from natural scientists William Carpenter and Charles Wyville-Thomson, who mounted expeditions in 1868 and 1869 on the vessels HMS Lightening and HMS Porcupine to sample the deep ocean off the British Isles, Spain and the Mediterranean. The findings of these expeditions, which Wyville-Thomson published in his 1873 book The Depths of the Sea , confirmed the existence of animal life to depths of 650 fathoms — including all the marine invertebrate groups — and suggested that oceanic circulation exists in the deep sea.

This convinced the Royal Society of London and the Royal Navy to organize the circumnavigating voyage of HMS Challenger in the 1870s. In part, the expedition's purpose was to survey potential routes for submarine telegraph cables, and so the links between scientific exploration and human use of the deep sea were established in the very early days of oceanography. The Challenger expedition was a watershed for deep-ocean science, establishing the basic patterns of distribution of deep-sea animals, and that their main food source was the rain of organic material from surface waters.

In the 1950s, the Danish Expedition Foundation's Galathea voyage established that life occurred at depths of more than 10km in the Philippines Trench. In 1960 marine explorers Auguste Picard and Don Walsh reached the bottom of the Challenger Deep in the Marianas Trench, at a depth estimated to be 10,916 meters--the deepest part of the ocean — where they observed flatfish from the porthole of their pressure sphere. This feat was not repeated until 2012 when James Cameron visited the bottom of the Challenger Deep in the submersible Deepsea Challenger .

Hype or hyper-diversity in the deep sea?

While working at Woods Hole Oceanographic Institution in the late 1960s, scientists Howard Sanders and Robert Hessler developed new types of deep-sea trawls called epibenthic sleds that featured extra- fine mesh in the nets. When the new trawls were tested, they recovered an astonishing diversity of species from the deep sea. It became apparent that the species richness of deep-sea communities actually increased with greater depth to a peak somewhere on the continental slope between 2,000 and 4,000 meters depth. Beyond these depths, diversity appeared to decrease (but not everywhere), or the pattern was unclear.

How to explain this amazing diversity in the deep sea? Initially, scientists credited the species richness to the stability of environmental conditions in the deep ocean, which would support extreme specialization of the animals and thus allow many species to coexist. This is known as the stability-time hypothesis. Some scientists considered that small-scale variations of the sediments of the deep ocean, including reworking of seabed by animals, was important in maintaining microhabitats for many species. In the late 1970s other scientists suggested that conditions in shallow waters allow competitive exclusion, where relatively few species dominate the ecosystem, whereas in deeper waters environmental factors associated with depth and a reduced food supply promote biological communities with more diversity.

Fred Grassle and Nancy Maciolek added substantially to our knowledge of deep-sea biodiversity when they published a study of the continental slope of the eastern coast of the USA in the early 1990s. Grassle and Maciolek based their study on quantitative samples of deep-sea sediments taken with box cores. These contraptions retrieve a neat cube-shaped chunk of the seabed and bring it to the surface enclosed in a steel box. Scientists then sieve the mud and count and identify the tiny animals living in the sediment.

In a heroic effort, Grassle and Maciolek analyzed 233 box cores, an equivalent of 21 square meters of the seabed, identifying 90,677 specimens and 798 species. They estimated that they found approximately 100 species per 100 km along the seabed they sampled. Extrapolations of this figure suggested that there may be 1 - 10 million macrofaunal species in the deep sea.

What's more, some scientists argued that Grassle and Maciolek's estimates represented only a small part of the species diversity in the ocean depths. Dr John Lambshead of London's Natural History Museum pointed out that Grassle and Maciolek had not examined the smallest animals in sediments — the meiofauna — made up of tiny nematode worms, copepods and other animals. These are at least an order of magnitude more diverse than the macrofauna, suggesting that as many as 100 million species may inhabit the deep ocean.

However, given that the latest approximation of the Earth's biodiversity is 10 million species in total, Lambshead's number appears to be an overestimate. Scientists have since realized that there are major problems with estimating the species richness of large areas of the deep sea based on local samples. Today we understand that species diversity in the deep ocean is high, but we still don't know how many species live in the sediments of the continental slope and abyssal plains. We also don't understand the patterns of their horizontal distribution or the reasons for the parabolic pattern of species diversity as it relates to depth. Evidence suggests, however, that the functioning of deep-sea ecosystems depends on a high diversity of animals — although exactly why remains open to conjecture.

The creation of deep-sea environments: "Drifters" and "Fixists"

In 1912, German scientist Alfred Wegener put forward his theory of continental drift to address many questions that engaged the geologists and biologists of his time. For example, why do the continents appear to fit together as though they had once been joined? Why are many of the large mountain ranges coastal? And, perhaps most intriguing, why do the rocks and fossil biotas (combined plant and animal life) on disconnected land masses appear to be so similar?

Wegener's theory provoked a major scientific controversy that raged for more than 50 years between "drifters" and "fixists." Critics of Wegener's — the "fixists" — pointed out that Wegener's proposed mechanism for drift was flawed.

In the search for an alternate mechanism to explain continental drift, British geologist Arthur Holmes suggested that radioactive elements in the Earth were generating heat and causing convection currents that made the Earth's mantle fluid. Holmes argued that the mantle would then rise up under the continents and split them apart, generating ocean basins and carrying the landmasses along on the horizontally-moving currents.

Following World War II, scientific expeditions employing deep-sea cameras, continuously recording echo-sounders, deep-seismic profilers and magnetometers lent support to the arguments of Holmes and his fellow "drifters." Scientists realized that the deep sea hosted a vast network of mid-ocean ridges located roughly in the center of the ocean basins. These ridges were characterized by fresh pillow lavas, sparse sediment cover, intense seismic activity and anomalously high heat flow. Scientists found geologically-synchronous magnetic reversals in the rocks of the ocean crust moving away from either side of the mid-ocean ridges. Added to this was the fact that nowhere could scientists find sediments older than the Cretaceous in age. Together, these findings suggested that new oceanic crust was being formed along the mid-ocean ridges, while old oceanic plates are forced underneath continental plates and destroyed along the ocean trenches. By the late 1960s, the bitter scientific debate between the "fixists" and the "drifters" was finally settled.

Life without the sun

During the next decade, scientists investigating volcanic activity at mid-ocean ridges became interested in the associated phenomenon of hot springs in the deep sea. Anomalously high temperature readings over mid-ocean ridge axes led scientists to mount an expedition in 1977 to the 2.5 km-deep Galápagos Rift. From the submersible Alvin, the scientists observed plumes of warm water rising from within the pillow lavas on the seabed. Living amongst the pillows were dense communities of large vesicoyid clams, mussels, limpets and giant vestimentiferan tube worms (Siboglinidae). An abundance of bacteria around the Galápagos Rift site immediately suggested that these communities might be based on bacterial chemosynthesis, or chemolithotrophy, using chemical energy obtained by oxidizing hydrogen sulphide to drive carbon fixation. Subsequent investigation confirmed that the giant tube worms, clams and mussels actually hosted symbiotic sulphur-oxidizing bacteria in their tissues.

The discovery caused huge excitement in the scientific community. Here was life thriving in the deep sea, where primary production — the basis of the food web — was independent from the sun's energy. Furthermore, as scientists discovered additional vent communities and surveyed elsewhere in the mid-ocean ridge system, they found that environmental conditions were extreme, with high temperatures, acidic waters, hypoxia (lack of oxygen) and the presence of toxic chemicals the norm.

The implications of this were enormous and went well beyond the study of the ocean itself. First, it meant that life could exist elsewhere in our solar system in environments previously thought too extreme. Second, it widened the potential area for habitable planets around suns elsewhere in the universe. For example, the discovery in 2000 of the Lost City alkaline hydrothermal vents presented an environment that some scientists suggest is analogous to the conditions in which life evolved on Earth.

Subsequently, chemosynthesis has been discovered in many places in the ocean, including deep-sea hydrocarbon seeps, in large falls of organic matter such as whale carcasses, and from shallow-water sediments associated with, for example, seagrass beds.

Drawing down the oceans' natural capital

Over the past two decades, we've developed a much deeper understanding of the relationship between humankind and the natural world, including the Earth's oceans. In 1997 Robert Costanza and his colleagues published a paper in Nature that estimated the economic value of the goods and services provided by global ecosystems. Costanza and his colleagues argued that the living resources of Earth could be viewed as a form of natural capital with a value averaging $33 trillion per annum, upon which the entire human economy depended. These goods and services were later grouped into supporting (e.g. primary production), provisioning (e.g. food), regulating (climate regulation) and cultural (e.g. education) services.

While this knowledge may have been intuitive for many people, Costanza's recasting of the environment in economic terms forced policymakers, industry leaders and others to recognize the importance of long-term environmental sustainability. With the support of international agencies such as the World Bank, many countries are now implementing natural capital accounting procedures through legislation. The purpose of this is to help monitor and regulate the use and degradation of the environment and to ensure that the critical ecosystem goods and services underpinning economic activity and human well-being are not undermined.

Although it seems like a modern preoccupation, sustainability is actually a centuries-old challenge, particularly as it relates to marine environments. For example, there is evidence that aboriginal fisheries in ancient times may have overexploited marine species. Certainly by medieval times in Europe, a thriving market for fish, coupled with other developments like changing agricultural practices, forced species such as salmon and sturgeon into decline.

The Industrial Revolution led to an increase in hunting fish, seals and whales, thanks to the development of steam- and then oil-powered fishing vessels that employed increasingly sophisticated means of catching animals. Pelagic whaling began in the early 20th century; the development of explosive harpoons, the ability to process whales at sea, and the strong demand for margarine made from whale oil all contributed to dramatic rises in catches. Despite the initiation of the International Whaling Commission in 1946, a serial depletion of whale populations took place from the largest, most valuable species (e.g. blue whale) through to the smallest species (minke whale). The failure to regulate catches of whales led to the establishment of a near-moratorium on whaling in 1986.

Over the same post-war period, fishing fleets underwent a major expansion and deployed increasingly powerful fishing vessels. Improved technologies for navigating, finding fish and catching them led to increasing pressure on fish stocks and the marine ecosystems in which they lived. In 1998, after analyzing catch statistics from the United Nations Food and Agricultural Organisation (FAO), Daniel Pauly and his colleagues from the University of British Columbia identified a global shift in fish catches from long-lived, high trophic level predators to short-lived, low trophic level invertebrates and plankton-eating fish. This was the first evidence that fishing was having a global impact on marine ecosystems, causing major changes in the structure of ocean food webs. Aside from the economic impacts of "fishing down the food web," evidence was accumulating that it also affected the vulnerability and/or resilience of marine ecosystems to shocks such as invasions by alien species and climate-change effects such as mass coral bleaching.

Further evidence came in 2003 from a study by Ransom Myers and Boris Worm. Myers and Worm documented a significant decline over time in the stocks of certain large, predatory fish after analyzing information from research trawl surveys and the catches of the Japanese long-line fleet. Other studies over the same time period suggested that sharks, seabirds and turtles were suffering large-scale declines as they became by-catch in many industrial fisheries. Scientists also asserted that some fishing technologies, such as bottom trawling, were extremely damaging to seabed communities — deep-sea ecosystems in particular — by documenting the devastation of cold-water coral communities.

These studies sparked a bitter war of words between marine ecologists, fishing industry executives and fisheries biologists. While it has now been demonstrated that fish stocks can recover if levels of exploitation by fisheries are reduced through management measures, it's clear that in many parts of the world's oceans this is not happening. Overall, global yields from marine capture fisheries are in a downward trajectory. By-catch of some marine predators, such as albatrosses, still poses a threat of extinction. Habitat destruction resulting from fishing is continuing.

In addition to overfishing, other human activities are damaging marine ecosystems. During the 1960s and 1970s, several major accidents with oil tankers and oil installations resulted in serious oil spills. While oil pollution is still a significant problem, as illustrated by the Deepwater Horizon disaster in the Gulf of Mexico in 2010, other less-visible sources of pollution are causing large-scale degradation of the ocean.

Persistent organic pollutants and heavy metals such as mercury are being recognized as major health issues for marine animals (especially high trophic level predators, such as killer whales and tuna) and also for humans. The oceans are becoming the dumping ground for a wide range of chemicals from our personal care products and pharmaceuticals, as well as those that leach out of all manner of plastics that are floating in our seas. Agrochemicals are pouring into the oceans through rivers; in some cases these artificially fertilize coastal waters, generating blooms of algae which are broken down by bacteria, thus stripping the water of oxygen and creating dead zones.

Our release of greenhouse gases into the atmosphere, particularly carbon dioxide (CO2), is leading to a profound disturbance in ocean temperatures and ocean chemistry. Since the late 1970s, mass coral bleaching from ocean warming has killed large areas of tropical coral reefs. Marine animals are changing their distribution and the timing of their lifecycles, sometimes with catastrophic effects across the wider ecosystem. Such effects are often propagated from lower levels of food webs up through to predators such as fish and seabirds: witness recent declines in spectacled sea duck populations in the Arctic and the decline of cod populations in the North Sea. The oceans are becoming more acidic, which affects the growth rates of animals with calcium carbonate shells or skeletons and has other negative impacts on animal physiology. Many of these different stresses on marine species interact in a form of "negative synergy", inducing more severe effects than if they had presented in isolation. At the ecosystem level these stresses reduce the resilience of marine ecosystems to "shocks" arising from large-scale effects, such as anomalous warming events associated with climate change.

Ocean future

The TEDTalks in The Deep Ocean illuminate many current topics in marine science and oceanic exploration. These include the call for better conservation management in the face of unprecedented threats to marine ecosystems, the discovery and application of as-yet-untapped natural resources from the ocean depths, and the quest for improved technologies to support both of these endeavors. As Sylvia Earle eloquently reminds us in her 2009 TEDTalk, the oceans are critically important to maintaining the planet in a condition that is habitable, and better cooperative, international management of marine ecosystems is essential. However, as other TED speakers like Robert Ballard and Craig Venter argue, the oceans should also interest us because they contain vast untapped resources: unexploited mineral resources as well as genes, proteins and other biomolecules of marine life, which may furnish the medicines and industrial materials of the future.

Smart management of these natural resources requires knowledge, as do our efforts to ensure the oceans' ongoing species richness and their critical function in maintaining the Earth system. In their TEDTalks, explorers and scientists Edith Widder, Mike deGruy and Craig Venter share some of the amazing physical and biological features of ocean habitats and describe how new technologies allow more careful study and exploitation of deep-sea environments.

Despite these advances, there are still enormous gaps in our knowledge. In a TEDTalk he gave in 2008, Robert Ballard noted that many parts of the ocean remain entirely unexplored and he advocated for increased resources for organizations like NOAA. As many of the TED speakers in The Deep Ocean argue, marine science is more important than ever because the oceans are under serious threat from a range of human impacts including global-scale climate change.

However, these speakers also offer a message of hope, underscoring that there is still time to alter the current trajectory of degradation. Scientists including TED speaker John Delaney present a vision for the future where ecosystem-based management, coupled with the advent of new technologies that allow us to monitor ocean health in real time, provide us with tools to heal marine ecosystems. This may allow us to restore their capacity to provide goods and services for humankind over the long term. Measures such as marine-protected areas can maintain the oceans' important biogeochemical functions, but will also conserve the remarkable and beautiful marine ecosystems that have culturally enriched the human experience for millennia.

We'll begin our journey into The Deep Ocean with legendary explorer and oceanographer Sylvia Earle, who shares disturbing data about the decline of marine ecosystems and proposes one method to protect what she calls "the blue heart of the planet."

Sylvia Earle

My wish: protect our oceans, relevant talks.

Craig Venter

On the verge of creating synthetic life.

David Gallo

Underwater astonishments.

Edith Widder

Glowing life in an underwater world.

John Delaney

Wiring an interactive ocean.

Mike deGruy

Hooked by an octopus.

Robert Ballard

The astonishing hidden world of the deep ocean.

ENCYCLOPEDIC ENTRY

Marine ecosystems.

Marine ecosystems are aquatic environments with high levels of dissolved salt. These include the open ocean, the deep-sea ocean, and coastal marine ecosystems, each of which has different physical and biological characteristics.

Biology, Ecology, Conservation, Earth Science, Oceanography

Coral Reef State Park

Coral reefs are a diverse form of marine ecosystem, which in total may account for a quarter of all ocean species. Several types of fish and coral are shown here at John Pennekamp Coral Reef State Park in Florida, United States.

Photograph by James L. Amos

Learning materials

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• Explorer Classroom: Shipwrecks and Shipworms with Reuben Shipway | October 31

Marine ecosystems are aquatic environments with high levels of dissolved salt, such as those found in or near the ocean. Marine ecosystems are defined by their unique biotic (living) and abiotic (nonliving) factors. Biotic factors include plants, animals, and microbes; important a biotic factors include the amount of sunlight in the ecosystem , the amount of oxygen and nutrients dissolved in the water, proximity to land, depth, and temperature . Sunlight is one of the most important a biotic factors for marine ecosystems . It’s so important that scientists classify parts of marine ecosystems —up to three—by the amount of light they receive. The topmost part of a marine ecosystem is the euphotic zone , extending down as far as 200 meters (656 feet) below the surface. At this depth, there is sufficient light for regular photosynthetic activity. Most marine life inhabits this zone. Below the euphotic zone is the dysphotic zone , which can reach from 200 to as deep as 1,000 meters (656 to 3,280 feet) below the surface. At these depths, sunlight is still available, but only enough to facilitate some photosynthesis. Below the dysphotic zone lies the aphotic zone , which does not receive any sunlight. Types of Marine Ecosystems Scientists divide marine ecosystems into several broad categories, although there are discrepancies depending on the source about what qualifies as a marine ecosystem . The number of marine ecosystems is actively debated. Although there is some disagreement, several types of marine ecosystems are largely agreed on: estuaries, salt marshes , mangrove forests, coral reefs, the open ocean, and the deep-sea ocean. An estuary is a coastal zone where oceans meet rivers. Here, nutrients and salts from the ocean mix with those from the river in regions sheltered from extreme weather . As a result, estuaries are among the most productive places on Earth and support many types of life. In addition, because they are located where rivers join the ocean, estuaries have traditionally supported many human communities and activities like fishing, shipping, and transportation. While estuaries form where ocean meets rivers, salt marshes occur where oceans meet land. These places are rich in nutrients from sediment brought in by the ocean. Marshes are regularly flooded by high tides , making the surrounding ground wet and salty. As a result, the soil is low in oxygen and filled with decomposing matter. These ecosystems are dominated by low-growing shrubs and grasses. Another coastal ecosystem is the mangrove forest. Mangrove forests are found in tropical areas. These ecosystems frequently flood with ocean water, submerging the roots of mangrove trees. The root systems of mangroves filter out salt and sit above ground to access oxygen . These trees provide a home for a variety of species. Animals, such as fish, crabs, shrimp, reptiles, and amphibians, live among the mangrove’s roots while its canopy provides a nesting site for birds. A bit farther out into the tropical sea are coral reefs, euphotic-zone ecosystems built from the exoskeleton secreted by coral polyps. These exoskeletons form complex structures that shelter many different organisms. Coral reefs are extremely diverse ecosystems that host sponges, crustaceans, mollusks, fish, turtles, sharks, dolphins, and many more creatures. By some counts, coral reefs can account for a quarter of all ocean species. Beyond the coral reefs lies the open ocean. Open ocean ecosystems vary widely as the depth of the ocean changes. At the surface of the ocean, the euphotic zone , the ecosystem receives plenty of light and oxygen , is fairly warm, and supports many photosynthetic organisms. Many of the organisms that we associate with marine ecosystems , such as whales, dolphins, octopi, and sharks, live in the open ocean. As the depth of the ocean increases, it gets darker, colder, and with less available oxygen . Organisms living in deep-sea ecosystems within the dysphotic and aphotic zones have unusual adaptations that help them survive in these challenging environments. Some organisms have extremely large mouths that allow them to catch whatever nutrients fall from shallower ocean depths. Others have adapted to get their energy via chemosynthesis of chemicals from hydrothermal vents.

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Related Resources

Smithsonian Ocean

Ocean Through Time

Introduction, precambrian, at the smithsonian.

The ocean may seem like a vast and unchanging landscape, but the reality is that the world beneath the waves has continuously evolved over time. As terrestrial creatures, humans are largely unaware that much of life's history has taken place in the ocean. Indeed, life had been evolving and changing for more than 3 billion years—the majority of the planet's existence—before the first creatures made their way out of the water.

The first ocean lifeforms were microscopic, so small they would be invisible to the naked eye. Later, bizarre and alien-like creatures reigned supreme. Even creatures more familiar to us, like sharks, whales, and octopuses have long and storied pasts with ancestors very different than the creatures now roaming the seas. Some species existed for a geological moment before they went extinct, while others slowly adapted to changing seas. Evolution takes time, and when the ocean changed too rapidly for species to respond, mass extinctions occurred across the globe. This has happened five times and could happen again.

Are You An Educator?

Shortly after its formation, planet Earth was very different than the planet we are familiar with today. During Earth’s infancy, when the solar system was also beginning to take shape, the world’s surface was constantly bombarded by massive asteroids and comets, some over 120 miles (200 km) in diameter. For the first 500 million years or so, the environment was quite unstable.

The First Oceans of the Hadean

Between asteroid and comet bombardments, scientists believe enough time passed for vaporized water to condense and settle on the earth’s surface. According to the most recent scientific studies, an ancient ocean likely covered the entire planet 150 million years after the formation of Earth, about 4.4 billion years ago. Scientists know this through the discovery of ancient zircon crystals that were dated around this time. These crystals can hold up against temperatures that would melt and destroy most other rocks, and a subset discovered in Australia have a specific chemistry that indicates the crystals formed through a sedimentary process in a cool and wet environment—what scientists infer to be an ancient ocean floor.

The Microbes of the Archean

The first lifeforms emerged at least 3.5 billion years ago. These were simple, single-celled microbes that probably lived near hydrothermal vents, places where hot water spews from beneath the earth's crust and carries minerals from below. It was from this mineral-rich water that microbes obtained energy. The atmosphere at this point did not contain any oxygen. Instead, it consisted of methane, carbon dioxide, and hydrogen sulfide—gases that vented from the cooling planet through volcanic eruptions. Without oxygen, microbes most likely produced energy using sulfur. Microbes near hydrothermal vents in today’s oceans still carry out similar chemical reactions to obtain energy where sunlight does not exist.

By 2.3 billion years ago a bacterium emerged that could convert sunlight into usable energy. In the process, gaseous oxygen was formed. This blue-green microbe called a cyanobacterium was likely the first photosynthetic organism—and it was a game changer in the story of life on Earth. Over millions of years, oxygen continued to accumulate in the atmosphere, thanks to cyanobacteria and other photosynthetic organisms. It was this oxygen that would allow complex life to thrive in the millennia to come.

The World Takes Shape

By 650 million years ago the first supercontinent, Rodinia, formed. It is unclear exactly how big Rodinia was, although it is likely that its core landmass was the land that is now North America. The familiar shapes and locations of today’s continents were not the same—both Asia and Africa were split into pieces, Antarctica butted up against India and Australia, and the Americas were warped into unrecognizable shapes. On either side of the continent were the Panthalassic and the Pan-African Oceans.

Complex Life in the Ediacaran

The first recorded complex life forms appear around 560 million years ago, though they were very different than the creatures we are familiar with today. Many were soft-bodied, with only a few tube-like creatures having a stiff outer sheath. In some places, forests of fern-like fronds covered the ocean floor, but since they grew at depths beyond where light could reach they obtained energy by absorbing nutrients, like carbon, directly from the water rather than through photosynthesis. Unlike the filter feeding invertebrates of today, such as sea pens, these Ediacaran fronds likely did not have digestive organs and instead directly absorbed simple molecules, in a similar manner as bacteria. They also likely left no living descendants.

Other creatures relied on a thick microbial matt that covered the ocean floor for a source of energy. The first animals feasted on this dense matt of microbes. Some were unnamed burrowers, known only by the trails they left behind that evolved from aimless wanderers to proficient consumers with organized foraging routes. Other creatures, believed to be the early ancestors of animals, had bilateral symmetry, meaning that the left and right sides of the body were mirror images of each other. Spriggina is often compared to later arthropods, like the trilobites. The earliest confirmed animal, Dickinsonia moved along the seafloor, periodically parking in one place to consume the microbes and once that spot became depleted, moving to a more plentiful site. Another, Kimberella , had a proboscis that it used to rake the microbes towards itself to feed. These creatures have a hint of familiarity, but one of the most unique creatures of the Ediacaran is Tribrachidium . It had three spiraling arms that coiled into a disk. Trilateral symmetry, a rarity today, was a common feature in Ediacaran creatures.

Viewed from space, the Paleozoic Earth would be a foreign world. During this era, seas flooded the continents and receded several times. During the early Paleozoic three small continents— Laurentia, Siberia, and Baltica—split apart from the rest of the supercontinent Gondwana and formed the Lapetus Ocean in between. Through the Ordovician period, the continents continued to drift and by the Silurian Period, Baltica collided with Laurentia, an event that resulted in today’s Appalachian Mountains. This new continent called Euramerica, and three newly-formed oceans, the Iapetus, Rheic, and Paleo-Tethys, spanned the smaller continents and Gondwana. By the end of the Paleozoic, the supercontinent Pangaea was beginning to take shape. Euramerica plowed into Gondwana, an event that caused many of the low-lying seas to dry up. Surrounding the entire continent, the Panthalassic Ocean covered the rest of the globe. Plants began to grow on land during the Ordovician, followed by invertebrates during the Silurian and finally vertebrates during the late Devonian. These early land dwellers were amphibian-like, eventually giving rise to reptiles by the end of the era.

Cambrian Explosion

The Cambrian period occurred approximately 542-488 million years ago and included the biggest evolutionary explosion in Earth’s history. Some researchers think this happened due to a combination of a warming climate, more oxygen in the ocean, and the creation of extensive shallow-water marine habitats. This environment would be ideal for the proliferation of new types of animals, including those that were larger and more complex in their body shapes and ecologies than their ancestors. The world’s first predators took to scanning the seabed from above or hiding in the sediments of the seafloor as disguised ambushers. On the seafloor, sponge-like creatures called Archaeocyatha grew in dense mounds and became prolific reef builders of the ocean. Though the first creatures to have shells arose in the Ediacaran, by the Cambrian this body feature became more common and it would prove as a critical defense mechanism against hungry predators. Many of these creatures were discovered in the Burgess Shale , an area of the Canadian Rockies with a large deposit of preserved Cambrian-age fossils

The First Predators

The largest and most fearsome looking predators to roam the seas during the Cambrian were the anomalocarids. The largest intact specimens discovered reach up to 3 feet in length. Some species of anomalocarids used two curled appendages to capture their prey and reel it in to a square ring of jagged teeth. They would also use crushing jaws to tear through the protective armor of hard creatures like trilobites. But unlike many of its relatives, one species of anomalocarid doesn't seem to be an apex predator. Like the whale shark and basking shark of today, the large shrimp-like creature called Tamisiocaris borealis was a filter feeder, and likely the first ever to live in the ocean. Scientists think the feather-like structures on its head were used to rake plankton from the sea. The appendages had finely spaced spines, further divided by smaller spines, which would have formed an efficient trap for small plankton.

Another formidable predator, Hurdia victoria has been nicknamed the Tyrannosaurus rex of the Cambrian era due to its relatively large size. While it never reached the size of the largest anomalocarids, some specimens reached 50 cm (around 20 inches), which was large for a time when most animals were about as big as a fingernail. Its prey consisted of trilobites and other smaller animals crawling on the seafloor. But not all predators stalked their prey from above. The ancient worm Ottoia prolifica lived in a self-constructed u-shaped home below the ocean floor. From there, Ottoia prolifica ambushed prey, which it would swallow headfirst. Most of its prey were small shelled animals related to mollusks, as well as worms, though there is evidence that they sometimes resorted to cannibalism.

Despite the impressive adaptations of the world’s first predators, those that were preyed upon soon developed their own line of defenses. Hallucigenia sparsa , a worm, is notable for the porcupine-like spikes that covered its back—an efficient way to ward off hungry jaws. Opabinia took a different approach and evolved five mushroom-like eyes that allowed it to see predators approaching from many directions. Additionally, its segmented portions were filled with fluid in order to be more flexible, an important trait for avoiding capture.

The Tale of the Trilobite

Perhaps the most famous creatures to emerge during the Cambrian were the trilobites. Relatives of insects, crabs, and spiders, there were over 20,000 trilobite species that lived between the Cambrian and the end of the Paleozoic Era when they went extinct, some 252 million years ago. Prolific survivors with a segmented body plan that could be easily modified and altered, they soon dominated the seafloor. It seems no method for catching food was beyond the scope of what a trilobite could do—predation, scavenging, filter feeding, and even forming a symbiotic relationship with bacteria were all methods of feeding employed by at least one species.

There is also evidence that trilobites were social creatures, migrating caravan style across the seafloor and meeting for mass molting events where they collectively shed their hard exoskeletons. One species even has a trident “fork” that protrudes from his head, an adornment believed to attract the opposite sex. As jawed and stealthy predators began to emerge, their simple body plans proved to be easy fodder for predators, but the trilobites adapted in stride. Some would curl up like pill bugs, their segments fitting together like a lock and key. Others developed thorny spines that would make it difficult for probing jaws to take hold and bite. Burrowing underneath sand and mud was another hiding tactic.

Life during the Paleozoic

Throughout the existence of Earth, the explosions and extinctions of life often take their cue from global changes. The quadrupling of diversity during the Ordovician is no different. During this period, most of the continental land was a part of the supercontinent Gondwana. Through the movement of plate tectonics, Gondwana gradually shifted south until it reached the South Pole. As this happened, the balmy, moderate temperatures of the planet turned ice cold, massive glaciers formed, and sea level dropped as much of the water used to form the ice came from the sea. 

During the Ordovician, the majority of ocean life still lacked a backbone. Instead, life relied on stiff structures, like shells, to protect them from predators. Trilobites, armored by their stiff exoskeleton, remained prominent seafloor dwellers. Clams developed a dual shell system with left and right halves while brachiopods , a lesser-known shelled invertebrate, evolved top and bottom valves and occupied the muddy bottom. 

Predators, too, required a tough outer skeleton. The eurypterids, a group of arthropods, were some of the most fearsome predators and could grow up to six feet (2 meters). With long tails that ended in a spike, they are often called "sea scorpions." Though today cephalopods are best known as soft-bodied creatures such as squid and octopuses, this group began as shelled creatures. Their simple shells evolved into complex spirals like the one still used by the nautilus. Without many vertebrates to compete with, the cephalopods were top predators.  

Although the first vertebrates emerged during this time period, it wasn’t until millions of years later that they came to rule the seas. Vertebrates that lived during the Ordovician were jawless fish called ostracoderms that had protective plates covering their body. 

Though they largely live in the deep ocean today, during the Cambrian through the Permian, crinoid forests covered parts of the seafloor. Known as sea lilies for their beautiful, feathered arms, these creatures are cousins of modern sea stars and sea urchins. When they grew in dense groups they created a protected, diverse ecosystem for other creatures to call home. But unlike the trees that make up the forests on land, crinoids are not plants. The invertebrates feed by catching drifting particles in their many arms. In a forest full of crinoids, competition for food was tough, so they evolved a variety of stalk heights which enabled them to capture food at different levels above the seafloor. The base of their stalks was modified to anchor the animal securely in the soft sediment. Crinoids were relative skyscrapers in the community, sometimes towering at heights of up to two meters (6.5 feet). In a crinoid community, lacy bryozoans occupied a lower level. Below them, huge numbers of brachiopods monopolized the muddy bottom. By the Permian, sharks cruised above these crinoid forests, while smaller bony fishes and shelled cephalopods weaved among the crinoid stalks.

One unique predator that swam in the ocean during the Permian, around 260-290 million-years-ago, was the shark called Helicoprion . This shark had a spiral set of teeth resembling a buzz saw, unlike any other shark. It is so unique that to this day scientists are still unsure as to how the teeth sat within the shark's jaw. Another predator, the placoderm, was a fish that had bony plates covering its body. Without teeth, it used the sharp edges of the plates covering its jaw to slice through its prey. Though initially highly successful and diverse, placoderms only existed for 50 million years, while sharks, a lineage that began at a similar time, have lasted to modern times.

Permian Extinction

The largest extinction ever in the history of Earth is the Permian extinction, an event that occurred roughly 252 million years ago. Scientists estimate that 90 percent of marine species disappeared over the course of about 60,000 years. The extinction was a response to dramatic changes in the Earth's atmosphere. Massive volcanic eruptions, spanning millions of years, spewed carbon dioxide and toxic gases out from inner Earth. As the gases accumulated temperatures rapidly fluctuated, oxygen levels plummeted, and the ocean became more acidic from acid rain. Ash that blocked the sun initially caused Earth's temperature to plummet, but lava soon burned coal deposits that released the greenhouse gas carbon dioxide into the atmosphere, raising the temperature.

The end Permian extinction drastically cut the diversity of life on Earth. Some groups went extinct, while a few species in other groups made it through. Sea urchins, once diverse during the Permian, were devastated—only one species survived. Ammonites, too, were hard hit. But the few that did survive became some of the most diverse predatory cephalopods.

The world during the Mesozoic Era was a place both foreign and yet familiar when compared to Earth today. At this time, Pangea broke apart, and the massive Panthalassa Ocean broke into multiple basins. The Tethys Ocean split Asia from the rest of the land and the Atlantic Ocean began to form. The world was warm, keeping large ice caps from forming, which led to high global sea levels by the Jurassic that continued into the Cretaceous.

Reptiles of the Sea

Before large mammals, reptiles ruled the ocean. During the Mesozoic, the time period when dinosaurs roamed on land, many of these large creatures were the top predators in the ocean food chain and fed on fish, cephalopods, bivalves, and even one another. The most notable of these reptiles were the ichthyosaurs, plesiosaurs, mosasaurs, and sea turtles. Although they lived at a similar time as dinosaurs, marine reptiles were not dinosaurs since they evolved from a different ancestor. In fact, many of the reptiles in the ocean were only distantly related to one another. While the mosasaurs evolved from land-dwelling lizards, plesiosaurs, ichthyosaurs, and turtles each had their own separate evolutionary lineage.

At first glance, an ichthyosaur looks much like dolphins that live today. But ichthyosaurs are not mammals, nor are they fish, they are reptiles. Just as whales and sharks have adapted similar body plans to maximize swimming efficiency, ichthyosaurs evolved streamlined bodies built for swimming. The first ichthyosaurs that emerged roughly 250 million years ago had horizontally elongated tails and swam by undulating their entire bodies from side to side like an eel. But as they evolved large crescent shape tails, similar to those of present-day tuna, they began to propel themselves by fanning only their tail. This transformation indicates that ichthyosaurs likely began as coastal dwellers and then gradually moved to life in the open ocean. Like most fossilized creatures, it is difficult to assess exactly what they ate, but a few discoveries of fossilized meals indicate they preyed upon squid and small fish.

In the early 1800s, Mary Anning , a young paleontologist, discovered a peculiar fossil. It turns out it was the first discovered plesiosaur. These reptiles are identified by their four flippered limbs and (for most) a long neck. In coordinated movements the four flippers would equally propel the plesiosaur forward, a unique swimming method in the animal kingdom. While four flippered animals like sea turtles do exist, these creatures predominantly use the front flippers for thrust and the back for steering. Most plesiosaurs were predators. Some likely grazed along the seafloor looking for soft-bodied prey while others likely aggressively ambushed their prey from below, much like the great white shark of today.

Mosasaurs were relative latecomers during the span of the Mesozoic. While ichthyosaurs, plesiosaurs, and turtles reigned supreme since the early Triassic, the first mosasaur didn't emerge until the late Cretaceous, about 99 million years ago. But in a short period of time, they quickly diversified. Some developed bulbous teeth that they used to hammer away at oyster-like bivalves, while others developed razor-like teeth that could pierce and shred larger prey, including other mosasaurs. Most lived in shallow waters, but some, like the Tylosaurus , traveled far offshore and dove to deeper depths. Fossils of mosasaurs have been found on every continent, including Antarctica, indicating they lived throughout the entire globe. Like the dinosaurs and other reptiles in the sea, mosasaurs went extinct at the end of the Cretaceous.

The first fully marine turtles emerged during the Cretaceous Period, a span of time lasting between 145 and 66 million years ago. By 120 million years ago, they resembled the sea turtles we are familiar with today. The largest, Archelon , measured up to 15 feet from head to tail.

The first fully marine turtles emerged during the Cretaceous Period. By 120 million years ago, they resembled the sea turtles we are familiar with today.

Bottom of the Food Chain

During the Mesozoic Era much of the plankton that exist today evolved. Coccolithophorids, microscopic plankton with calcium carbonate skeletons, were especially abundant and diverse during the Cretaceous Period. When coccolithophorids die and accumulate on the seafloor they form limestone and chalk. Trillions of these skeletons from the Cretaceous make up the famous White Cliffs in Dover, England. Oil, too, comes from dead plankton that accumulates on the seafloor and is buried for millions of years, but these plankton lack shells. More than 60 percent of the world's oil began as microscopic marine plankton in the Jurassic and Cretaceous.

Ancient Reefs

At the beginning of the Mesozoic Era during the Triassic, the ocean’s reefs were hard hit by the Permian extinction. It took millions of years for new, diverse seafloor ecosystems to evolve. By the time of the Jurassic, the seafloor was again thriving, but the reef's composition was different than the reefs we think of today. Presently, corals are the famous creatures known for their reef-building. They were also fairly abundant at various times through the Paleozoic Era and formed extensive reefs by the Devonian Period. But about 100 million years ago , during the heyday of the dinosaurs, the majority of reefs were built by mollusks called rudist clams. Like modern clams, rudists were bivalves , with two shells (or valves) joined at a hinge. But they sure didn’t look like modern clams ! One major group of rudists grew upright, like big ice cream cones standing on end. The bottom valve was anchored on the ocean floor. Only the upper few inches poked above the sediments. The second major group of rudists had horn-shaped shells that lay flat on the ocean floor, preventing strong currents from flipping them over or washing them away.

Arms Race for Survival

The Mesozoic seas were thriving ecosystems structured much like the ecosystems that exist today, with phytoplankton forming the base of the food web and large predators at the top. The higher sea level during the Jurassic and Cenozoic created large areas of shallow seas where toothed fish, reptiles, birds, and flying pterosaurs stalked their prey. The first teleost fishes, fish with mobile jaws, evolved and their gaping, flexible mouths were effective for gulping prey. Carnivorous fishes like Xiphactinus were the most numerous predators in the Late Cretaceous seas. But that didn’t mean that other creatures were defenseless. Spines, spikes, and thick shells evolved to deter hungry predators, which in turn evolved teeth, claws, and beaks, with some even swallowing prey whole.

The Cretaceous-Paleogene Extinction

Around 66 million years ago a six-mile-wide asteroid smashed to Earth’s surface, an impact that caused tsunamis, acid rain, wildfire, and global cooling. With such a catastrophic change many species went extinct worldwide. One of the most famous extinctions because of the resulting disappearance of the dinosaurs, it is known as the K/Pg extinction.  

The effects of this asteroid collision were global. Near the asteroid’s point of impact in present-day Mexico, shock waves would have obliterated any life. The rock under the shallow ocean where the asteroid hit would have been instantly vaporized and flung into the atmosphere where it would have acted as a veil and blocked the sun. Sulfur from vaporized rock made acid rain which likely killed corals and most plankton with shells made of lime. Organisms that lived beyond this impact zone would not have died immediately, but as their ecosystems collapsed, they too succumbed. Coastal areas were devastated by gigantic tsunamis that washed far inland. Increased heat sparked wildfires that ravaged forests and plains. Clouds of soot darkened the sky.

As the dust and soot lingered in the atmosphere, they blocked the warmth from the sun and Earth’s temperature dropped. Without sunlight, many plants on land and phytoplankton in the sea likely died. And without these sources of food, ecosystems across the globe collapsed. Ammonites, large marine reptiles, rudist clams, and many species of phytoplankton were particularly hard hit in the ocean.

Yet, life persisted. Years after the asteroid’s collision some organisms began to make a comeback. The K/Pg extinction cleared the way for new lineages of life to thrive. The mammals, once small and rodent-like, took advantage of the dinosaurs’ extinction and evolved in new directions, with some lineages eventually giving rise to the whales, seals, and manatees that live in the ocean today.

The K/Pg extinction marked the end of the Mesozoic Era and the beginning of the Cenozoic Era, the Era that we live in today. At the beginning of the Cenozoic, the world’s continents and ocean basins were very similar to those that exist today, though the continents have continued to shift.

Shifting Plates

Around 34 million years ago the ocean temperature plunged in response to shifts in tectonic plates and a drop in atmospheric carbon dioxide. As South America and Australia broke away from Antarctica, oceanic currents dramatically changed and affected marine food webs across the globe. Mammals diversified rapidly, evolving new ways to feed, move about, and keep warm in the chilled ocean waters.

Later, a seemingly small land divide emerged that shifted global circulation again. For much of the Cenozoic, a seaway existed between the Pacific and Caribbean that allowed for ocean water and species to move between them. That all changed when the Pacific tectonic plate butted up against the Caribbean and South American plates during the Pliocene and the Isthmus of Panama began to take shape. This tectonic collision caused volcanic activity and the formation of mountains that stretched from North America to South America. This caused cooling and continental ice sheet growth especially in the Northern Hemisphere. The resultant drop in sea level further expanded the Panama land bridge.

As the Caribbean was cut off from the Pacific, the Atlantic Ocean became slightly saltier, and the Gulf Stream strengthened and propelled warm water from the equator up into the north. Today, the salty water of the Atlantic is a major engine for global ocean circulation. Ecosystems, too, reacted to the closure of the seaway. Cordoned off from the nutrient-rich waters of the Pacific, Caribbean species needed to adapt. The barrier led to the creation of new, closely related species, such as the Pacific goliath grouper and the Atlantic goliath grouper. The lack of nutrients in the waters of the Caribbean resulted in the high diversity of corals and algae we see today. Some species were able to make the adjustment, but others didn't fare so well.

The Reign of Mammals

It is also during this time that the true giants of the world came to be. The largest animal to ever live on the planet is the blue whale. But to become so large required a special set of circumstances. Baleen whales didn’t begin to get really big until roughly 5.3 million years ago, at the transition between the Miocene and the Pliocene. Scientists believe that this was a response to changes in the ocean environment. Around 3 million years ago the poles and temperate latitudes of the Earth were covered in ice. It was a period of time in which there was high seasonality and ice would consistently melt and refreeze over again. With each glacial melt came loads of nutrients from inland soils that flooded into the ocean and created pockets of high nutrients in coastal areas.

The icy landscape also created strong winds that pushed the water and created pockets of upwelling, much like how winds drive upwelling off the coast of California today. Also, as the world’s water froze in ice shelves, the oceans became saltier. This, in turn, drove large oceanic currents that brought nutrient rich water up from the depths of the ocean. In combination, these factors created a patchy ocean where pockets of nutrients were separated by miles of food deserts. Whales evolved massive bodies to not only store large quantities of energy but also to push aside the water for effective long-distance travel.

At the same time that baleen whales were growing to massive proportions feeding on tiny crustaceans, another marine mammal, Desmostylia, was grazing on kelp and seagrass in the shallows. These four-legged, gnarly-toothed creatures straddled the marine and terrestrial environments much like seals and sea lions of today, but with feet instead of flippers. By the middle of the Miocene they disappeared. They are the only order of marine mammals to go entirely extinct, and it is likely because sea cows and manatees were better suited for underwater life and outcompeted them for food.

Humans and the Ocean—The Anthropocene

Exploitation.

Extinction of large oceanic animals may seem like a modern-day tragedy—however, humans have been killing off species for quite some time, and the loss of Stellar’s sea cow is a perfect example.

The Stellar’s sea cow is a relative of today's manatees and dugongs that once lived in an area that spanned from Japan across the Bering Strait and down to the Baja Peninsula. They were massive creatures, measuring up to 30 feet (9 meters) in length and weighing up to 10 tons. Named by naturalist and explorer Georg Stellar during an expedition in the mid-1700s, the sea cow survived only 27 years after being officially named, until 1769. Although it was sought-after prey for hunters, the loss of the sea cow was likely tied to the disappearance of another sought-after ocean mammal, the sea otter . Voracious consumers of the sea urchin, sea otters controlled the population of the urchins. But as Russian and Aleut hunters began to exploit the sea otters for their pelts, the sea otter population plummeted. Without a predator to keep them in check, the urchin population exploded. Urchins eat kelp, just as the sea cows did. And so, with the massive numbers of hungry urchins decimating the kelp forests, it is likely the sea cows starved. 

Stellar’s sea cow is far from the only ocean creature brought to extinction by humans. In the 1800s, fishers and whalers traveling in the north slaughtered the flightless great auks by the thousands to supply food aboard ships, and by 1844 the species was extinct . The Japanese sea lion and Caribbean monk seal are other animals that have since been lost due to human exploitation.

Present Day

Today, the ocean is constantly being influenced by humans. The development of coastlines and overfishing are causing a significant loss in biodiversity. Pollution from runoff, oil spills, and plastic waste are killing species at an alarming rate. Carbon emissions from cars and power plants that provide electricity result in warming of our atmosphere, which is then melting glaciers and causing sea level to rise. Ocean currents are also responding to the fresher, warmer water. The excess carbon dioxide is dissolving into the water and creating more acidic seas.

As the world changes at a rate never before experienced in geologic time it is important to understand and reflect upon how past times of change affected life. A dramatically changing world often leads to mass extinctions, and in some cases, it takes millions of years for ecosystems to rebound, and they are never the same. The ocean will continue to exist— all life that inhabits it will not disappear, but a 6th mass extinction in the ocean would be very hard on humans.

A Priceless Collection

The Smithsonian’s National Museum of Natural History houses one of the largest and most important collections of animal fossils in the world. These are not, as you might expect, dinosaur fossils. Surprisingly, you’ll find them in the invertebrate collections—the home of soft-bodied creatures, that are hardly ever fossilized: strange, rare, and exquisitely preserved sea-dwelling organisms from the Burgess Shale . These Cambrian-age fossils, 508 million years old, were discovered one hundred years ago by then-head of the Smithsonian, Charles D. Walcott. Beginning in 1909, Walcott collected some 65,000 specimens from the Burgess Shale, an area of the Canadian Rockies with a large deposit of preserved Cambrian-age fossils. For the past century, scientists have continued to study these amazing fossils, opening new windows into the complex and fascinating history of rapid diversification of life on Earth, called the “Cambrian Explosion.” The Museum today has two displays about the Burgess Shale: one in the David H. Koch Hall of Fossils and another in the Sant Ocean Hall .

Ostracods and and Extinction

In a world that constantly changes, some species are winners and thrive in the new environment while others can’t cope and die out. But what determines the winners and losers? For some, it’s a matter of having the right anatomy. Ostracods, small shrimp-like creatures that live curled in shell-like casings, have a notable anatomical feature. In males, the penis is extremely large in comparison to the size of the rest of its body—it’s about a third of their size. But while size may be helpful in attracting mates in the short term, evolutionarily it can have its drawback. Smithsonian scientists Maria João Fernandes Martins and Gene Hunt have determined that ostracod species with larger penises are driven to extinction much faster than those with smaller penises. By studying ostracods that lived between 66 and 84 million years ago they determined that the species with larger penises became extinct 10 times faster than those with smaller penises. Another way to look at it is through time. While ostracods with small penises existed for an average of 15.5 million years, species with larger penises existed for only 1.6 million years. The study of ostracods is meant to shed light on a greater trend in evolution. Visual differences between sexes is not uncommon (think the peacock’s feather display and a moose’s antlers), and oftentimes while having a larger antler rack or brighter plumage is enticing for females, it can be detrimental to the male’s overall survival. This research suggests that species with larger adornments may be more susceptible to extinction.

Plankton Clues

Researcher Brian Huber studies microscopic fossils to learn about past climates. Specifically, he studies clues in the chemistry of foraminifera, a single-celled creature that both drifts in the ocean water column and sits at the bottom of the seafloor. The secret to how this microscopic creature informs us about our past climate lies in the shell. Foraminifera have an intricate shell covering that they build from molecules in the water. This shell is made of calcium carbonate and as the foraminifera builds its shell it takes oxygen molecules from the water to create the compound. The oxygen has different traits depending upon the temperature of the water. Some oxygen molecules are heavier than other oxygen molecules, a product of a bulkier core. The proportion of bulky oxygen to lighter oxygen enables scientists to determine what the temperature was when the foraminifera built its shell. By studying the shell chemistry of foraminifera over time scientists can see how temperature has changed. For example, shells from the Cretaceous show that the Antarctic ocean surface was a balmy 26 to 32 degrees C (79 to 90 degrees F).

The Evolution of Whales

From excavating fossilized whale skeletons in the Atacama Desert to examining them in the lab, researcher Nick Pyenson has dedicated his career to understanding the evolution of whales. His team has investigated questions that try to understand the evolution of whale anatomy, from the evolution of baleen to explaining why whales got so big . Through his travels around the globe, he and his team have discovered countless new species of ancient whales. The study of whale evolution in the past is becoming ever more relevant as today’s whales respond and adapt to a changing world.

Douglas Erwin has spent his life studying the rise and fall of early creatures. Specifically, this includes studying how animals evolved during the Ediacaran and Cambrian Periods. Due to Erwin’s research, it is now known that the first animal evolved during the Ediacaran and not the Cambrian like previously thought. By studying Permian fossils, Erwin has also contributed to our understanding of why the Permian Extinction—the largest extinction in Earth’s history—came to be.

Ichthyosaur Gravesite

In the middle of the Nevada desert there is a massive ichthyosaur gravesite. Berlin Ichthyosaur State Park is the resting place of many ancient reptiles called ichthyosaurs. About 37 Shonisaurus popularis have been uncovered so far. In the late 1800s miners searching for silver stumbled upon the fossils, and later in the 1950s they were unearthed and studied by Berkeley paleontologist Charles Camp. Today, Smithsonian scientists are using 3D scanning technology to continue the work of Camp and allow people from around the world to view the fossil skeletons.

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Home › Ocean Advocacy › #thinkocean › How do Humans impact the Ocean?

Humans Impact on the Ocean

The good news is it's not too late to turn things around

Every single person on our blue planet is connected to the Ocean. That means the choices we make can have a positive or negative impact on the Ocean.

Negative Human Effects

Habitat destruction.

Virtually all Ocean habitats have been affected in some way via drilling or mining, dredging for aggregates for concrete and other building materials, destructive anchoring, removal of corals and land “reclamation”.

Carbon Emissions

Since the industrial revolution, humans have increased carbon dioxide in the atmosphere to levels that have caused Ocean acidification and Ocean warming, amongst other climate related negative effects.

Chemical Pollution

There have been many disastrous chemical spills at sea and from industry on land, affecting animals immediately via ingestion, or long term, in changes to reproduction cycles and other biological processes.

Sadly, oil spills still occur, coating beaches, sinking to smother Ocean plant life and killing a wide variety of birds, fish and sea mammals.

Noise Pollution

Research shows that underwater noise from construction, shipping and naval vessels significantly impacts the natural behaviour of cetaceans and many other marine species.  This can be seen when mass beaching events occur or breeding success is diminished.

Plastic pollution

The world has woken up to the millions of tonnes of plastic that have entered the Ocean over the past 100 years. The impacts of this scourge will last a lot longer.

Overfishing

In many areas, factory fishing has destroyed local fish stocks, leaving too few adults to breed for the future.

Destructive Fishing

Certain fishing practices not only contribute to overfishing of their target species, but also damage the environment by dredging the seabed or catching other species that are thrown back dead.

Surface runoff

With increased urbanisation, tarmac and other manmade land surfaces contribute to petrol, diesel and other harmful chemicals easily flowing into rivers or directly into the Ocean.

Deoxygenation

The increase in the use of fertilisers for agriculture and warming ocean waters has contributed to eutrophication of the Ocean in certain areas of the world.  This means there is less available dissolved oxygen for native sea life, which can negatively impact biological processes.

Deep Sea Mining

A new issue facing the Ocean is that of deep sea mining.  The metals required in our laptops, phones and batteries can be found on the seafloor – but what damage will we do?

But all is not lost…

Despite the negativity surrounding the current state of our Ocean, the good news is that it’s not too late to turn things around. We just have to take positive steps now.

There are many ways that people around the world are having a positive effect on the Ocean every day…

Microbead ban.

Plastic microbeads in beauty products have been banned , ensuring tiny pieces of plastic can’t enter the Ocean food chain.

Circular economy

More businesses are becoming involved in circular economy models – this means that more materials are reused, shared, repaired, refurbished, remanufactured and recycled; thereby creating a closed system and minimising the use of new resources.

UN Ocean Decade

The United Nations have declared that the next decade will focus on Ocean Science and ecosystem restoration. Great news for a joined up global effort to protect the Ocean.

Sustainable Development Goals

The global Sustainable Development Goals will protect nature, especially goal 14 “Life Below Water”.

Marine Protected Areas

Increasing the protection of the Ocean via the designation of specially protected areas has had positive impacts on habitats and fish stocks in many locations.

Banning single use plastics

Many countries have taken steps to ban single use plastic items like straws, drink stirrers and cotton buds.

Meat free Monday

The growth of the Meat Free Monday movement is great for our Ocean.

There is a shift in voting patterns, with more voters choosing to vote for parties with the better green and blue credentials.

Sustainable fishing

The Marine Stewardship Council report that in 2019 sales of MSC certified  sustainable seafood  reached one million tonnes for the first time and demand for sustainable fish was on the increase.

We can all be conservationists, and many people are doing their bit at home to protect the Ocean. Find out ways you can #thinkocean.

Ocean habitat restoration

Around the world, many projects are now seeking to restore marine habitats, such as mangrove and seagrass .

All is not lost, take a look at some of the projects we’re working on around the world to have a positive impact.

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Essay on Sea Animals

Students are often asked to write an essay on Sea Animals in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on Sea Animals

Introduction.

Sea animals are a fascinating group of creatures that live in the ocean. They range from tiny plankton to the gigantic blue whale, the largest animal on Earth.

Variety of Sea Animals

There are countless types of sea animals. Some are fish like sharks and clownfish, while others are mammals like dolphins and seals. There are also sea turtles, octopuses, and countless species of invertebrates.

Importance of Sea Animals

Sea animals play vital roles in the ocean ecosystem. They help to balance the food chain and contribute to the health of coral reefs and seagrass beds.

Conservation

Sadly, many sea animals are threatened by pollution, climate change, and overfishing. It’s essential for us to protect these amazing creatures and the habitats they call home.

250 Words Essay on Sea Animals

Sea animals, a vast and diverse group of organisms, play a significant role in maintaining the balance of marine ecosystems. These creatures, ranging from microscopic plankton to the enormous blue whale, exhibit a myriad of adaptations that allow them to survive in various marine environments.

Classification and Adaptation

Marine fauna can be broadly classified into vertebrates, invertebrates, and other categories like mollusks, crustaceans, and echinoderms. Each group has unique adaptations to cope with the challenges of marine life. For instance, marine mammals like dolphins and whales have evolved streamlined bodies and powerful tails for efficient swimming.

Ecological Roles

Sea animals play diverse roles in marine ecosystems. Predators, such as sharks, maintain the balance of the food chain by controlling the population of their prey. Coral reefs, formed by tiny invertebrates, provide habitats for a plethora of marine species.

Threats and Conservation

Despite their importance, sea animals face numerous threats, including pollution, climate change, and overfishing. These anthropogenic pressures have led to drastic declines in many species’ populations. Conservation efforts, such as establishing marine protected areas and implementing sustainable fishing practices, are crucial to safeguard these creatures and the ecosystems they inhabit.

In conclusion, sea animals, with their stunning diversity and ecological significance, are an integral part of our planet. Their conservation is not just an ethical imperative but also vital for maintaining the health of our oceans and, by extension, the Earth’s overall wellbeing.

500 Words Essay on Sea Animals

Introduction: the aquatic realm, adaptations of sea animals.

Sea animals have evolved a wide range of remarkable adaptations that allow them to survive in diverse marine environments. From the shallowest tide pools to the deepest ocean trenches, marine creatures exhibit extraordinary resilience and versatility. For instance, the pressure-resistant structure of deep-sea creatures like the anglerfish or the ability of the mantis shrimp to see an array of colors that are invisible to the human eye, demonstrate the remarkable adaptability of marine life.

The Intricate Food Web

The marine food web is a complex and dynamic system, with multiple trophic levels, from the primary producers (phytoplankton) to apex predators such as sharks and orcas. Each species plays a unique role in maintaining the balance of the ecosystem. For example, sea otters control sea urchin populations, which in turn prevents kelp forests from being overgrazed. This interconnectedness underscores the importance of every species in the marine ecosystem.

Threats to Sea Animals

Conservation efforts.

Recognizing these threats, numerous conservation efforts are underway to protect sea animals and their habitats. These include the establishment of marine protected areas, efforts to reduce pollution, and sustainable fishing practices. Scientific research is also crucial, providing valuable insights into marine life and informing conservation strategies.

Conclusion: The Importance of Sea Animals

Sea animals are more than just fascinating creatures of the deep. They are vital components of our planet’s health, influencing climate regulation, food security, and livelihoods. Their survival is intricately tied to ours, and understanding them is not just a matter of scientific curiosity, but a necessity for our future. As we continue to explore the depths of the oceans, we must also strive to protect the myriad of life that resides within them.

If you’re looking for more, here are essays on other interesting topics:

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Team maps effects of human activity on marine species over time

"It is really hard to know how a species is doing by just looking out from your local coast, or dipping underwater on scuba," says Ben Halpern. "You only see a small patch of where a species lives and what it is experiencing, and only the few species you happen to see on that day." (Credit: Valerie Hukalo/Flickr )

You are free to share this article under the Attribution 4.0 International license.

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Researchers have created the first global assessment of cumulative human impacts to at-risk marine species over time.

Despite the fact that our planet is mostly ocean and human maritime activity is more intense than ever, we know remarkably little about the state of the ocean’s biodiversity—the variety and balance of species that support healthy and productive ecosystems. And it’s no surprise—marine biodiversity is complex, human impacts are uneven, and species respond differently to different stressors.

“It is really hard to know how a species is doing by just looking out from your local coast, or dipping underwater on scuba,” says Ben Halpern, a marine ecologist at the Bren School of Environmental Science & Management at the University of California, Santa Barbara and director of the National Center for Ecological Analysis and Synthesis. “You only see a small patch of where a species lives and what it is experiencing, and only the few species you happen to see on that day.”

Though valuable, these snapshots are only part of a much larger picture of cumulative human impacts on at-risk marine species. Even less obvious are changes in impact over time and assessments of vulnerability to these impacts, which differs across species.

Now, the new assessment will make the picture of marine biodiversity much clearer. Published in the journal Science , the assessment will broaden and deepen our understanding of the state of marine biodiversity and will go a long way toward concrete conservation measures for the most vulnerable members of the marine community.

Marine species with higher extinction risk

“This is the first study of its kind looking at the effects of human activity on marine species, and the first looking at changes over time,” says Casey O’Hara, a doctoral student in the Bren School. Taking data on 1,271 threatened and near-threatened marine species from the International Union for Conservation of Nature and Natural Resources’ (IUCN) Red List , the researchers mapped the at-risk species along range and anthropogenic stressors from 2003-2013.

“We focused on those species known to be at a higher risk of extinction because from a conservation perspective, it’s especially important to understand where and how our activities continue to jeopardize those species,” O’Hara says.

“Not every species is affected the same way by various human activities—some species are more sensitive to fishing pressures while others are more vulnerable to rising sea surface temperatures or ocean acidification.”

Mapping over a series of 11 years would also give the researchers a sense of cumulative human impact, a method they first used in a previous study that focused on representative marine habitats.

Where does human activity hit hardest?

It’s not a shock. Human impacts on marine biodiversity are increasing, dominated by fishing, direct human disturbance from land, and ocean acidification . But the authors made some unexpected discoveries.

The extent to which at-risk species face these pressures from human activities, and the pace at which the pressures are expanding and intensifying, is worrisome. Corals are the most widely impacted marine organism on Earth.

“I was surprised at the extent to which corals were impacted—coral species are facing impacts across essentially their entire ranges and those impacts are only getting more intense, particularly climate-related impacts,” O’Hara says.

“We hear stories of coral bleaching and the like, but our results really highlight the impact we are having.” The species of the Coral Triangle—the tropical waters connecting Indonesia, the Philippines, Papua New Guinea, and the Solomon Islands—are among the most affected by human impacts, as are species in the North Atlantic, North Sea, and Baltic Sea.

The information from this approach could give decision-makers a deeper understanding of where and how human activity affects marine biodiversity, which could lead to effective solutions. For instance, addressing areas of human impact overlap can maximize the benefits of conservation for several species in the area. Effective conservation measures can help ease the pressures of climate change phenomena such as ocean acidification or rising ocean temperatures.

The team might get the chance to put their findings to work later this year, at the UN Convention on Biological Diversity’s 15th Conference of Parties, where 197 participating nations and territories will convene on a framework to protect and conserve global biodiversity.

“That framework will include targets for protecting land and ocean areas globally, along the lines of President Biden’s executive order to protect 30% of US lands and coastal waters by 2030,” O’Hara says. “With our study we hope to highlight those areas where such protection can do the greatest good for those species and ecosystems at greatest risk.”

Source: UC Santa Barbara

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Aquatic ecosystems and global climate change.

Aquatic ecosystems are critical components of the global environment. In addition to being essential contributors to biodiversity and ecological productivity, they also provide a variety of services for human populations, including water for drinking and irrigation, recreational opportunities, and habitat for economically important fisheries. However, aquatic systems have been increasingly threatened, directly and indirectly, by human activities. In addition to the challenges posed by land-use change, environmental pollution, and water diversion, aquatic systems are expected to soon begin experiencing the added stress of global climate change.

“Aquatic Ecosystems and Global Climate Change” is the seventh in a series of reports examining the potential impacts of climate change on the U.S. environment. It details the likely impacts of climate change over the next century on U.S. aquatic ecosystems. Report authors, Drs. N. LeRoy Poff, Mark Brinson, and John Day, Jr. find:

• Increases in water temperatures as a result of climate change will alter fundamental ecological processes and the geographic distribution of aquatic species. Such impacts may be ameliorated if species attempt to adapt by migrating to suitable habitat. However, human alteration of potential migratory corridors may limit the ability of species to relocate, increasing the likelihood of species extinction and loss of biodiversity.
• Changes in seasonal patterns of precipitation and runoff will alter hydrologic characteristics of aquatic systems, affecting species composition and ecosystem productivity. Populations of aquatic organisms are sensitive to changes in the frequency, duration, and timing of extreme precipitation events, such as floods or droughts. Changes in the seasonal timing of snowmelt will alter stream flows, potentially interfering with the reproduction of many aquatic species.
• Climate change is likely to further stress sensitive freshwater and coastal wetlands, which are already adversely affected by a variety of other human impacts, such as altered flow regimes and deterioration of water quality. Wetlands are a critical habitat for many species that are poorly adapted for other environmental conditions and serve as important components of coastal and marine fisheries.
• Aquatic ecosystems have a limited ability to adapt to climate change. Reducing the likelihood of significant impacts to these systems will be critically dependent on human activities that reduce other sources of ecosystem stress and enhance adaptive capacity. These include maintaining riparian forests, reducing nutrient loading, restoring damaged ecosystems, minimizing groundwater withdrawal, and strategically placing any new reservoirs to minimize adverse effects.

The authors and the Center gratefully acknowledge the input of Drs. Virginia Burkett, Judy Meyer, Elizabeth Strange, and Alan Covich on this report. The Center would also like to thank Joel Smith of Stratus Consulting for his assistance in the management of this Environmental Impacts Series.

Executive Summary

Climate change of the magnitude projected for the United States over the next 100 years will cause significant changes to temperature regimes and precipitation patterns across the United States. Such alterations in climate pose serious risks for inland freshwater ecosystems (lakes, streams, rivers, wetlands) and coastal wetlands, and they may adversely affect numerous critical services they provide to human populations.

The geographic ranges of many aquatic and wetland species are determined by temperature. Average global surface temperatures are projected to increase by 1.5 to 5.8oC by 2100 (Houghton et al., 2001), but increases may be higher in the United States (Wigley, 1999). Projected increases in mean temperature in the United States are expected to greatly disrupt present patterns of plant and animal distributions in freshwater ecosystems and coastal wetlands. For example, cold-water fish like trout and salmon are projected to disappear from large portions of their current geographic range in the continental United States, when warming causes water temperature to exceed their thermal tolerance limits. Species that are isolated in habitats near thermal tolerance limits (like fish in Great Plains streams) or that occupy rare and vulnerable habitats (like alpine wetlands) may become extinct in the United States. In contrast, many fish species that prefer warmer water, such as largemouth bass and carp, will potentially expand their ranges in the United States and Canada as surface waters warm.

The productivity of inland freshwater and coastal wetland ecosystems also will be significantly altered by increases in water temperatures. Warmer waters are naturally more productive, but the particular species that flourish may be undesirable or even harmful. For example, the blooms of “nuisance” algae that occur in many lakes during warm, nutrient-rich periods can be expected to increase in frequency in the future. Large fish predators that require cool water may be lost from smaller lakes as surface water temperatures warm, and this may indirectly cause more blooms of nuisance algae, which can reduce water quality and pose potential health problems.

Warming in Alaska is expected to melt permafrost areas, allowing shallow summer groundwater tables to drop; the subsequent drying of wetlands will increase the risk of catastrophic peat fires and the release of vast quantities of carbon dioxide (CO2) and possibly methane into the atmosphere.

In addition to its independent effects, temperature changes will act synergistically with changes in the seasonal timing of runoff to freshwater and coastal systems. In broad terms, water quality will probably decline greatly, owing to expected summertime reductions in runoff and elevated temperatures. These effects will carry over to aquatic species because the life cycles of many are tied closely to the availability and seasonal timing of water from precipitation and runoff. In addition, the loss of winter snowpack will greatly reduce a major source of groundwater recharge and summer runoff, resulting in a potentially significant lowering of water levels in streams, rivers, lakes, and wetlands during the growing season.

The following summarizes the current understanding regarding the potential impacts of climate change on U.S. aquatic ecosystems:

1.   Aquatic and wetland ecosystems are very vulnerable to climate change. The metabolic rates of organisms and the overall productivity of ecosystems are directly regulated by temperature.  Projected increases in temperature are expected to disrupt present patterns of plant and animal distribution in aquatic ecosystems. Changes in precipitation and runoff modify the amount and quality of habitat for aquatic organisms, and thus, they indirectly influence ecosystem productivity and diversity.

2.   Increases in water temperature will cause a shift in the thermal suitability of aquatic habitats for resident species.  The success with which species can move across the landscape will depend on dispersal corridors, which vary regionally but are generally restricted by human activities. Fish in lowland streams and rivers that lack northward connections, and species that require cool water (e.g., trout and salmon), are likely to be the most severely affected. Some species will expand their ranges in the United States.

3.   Seasonal shifts in stream runoff will have significant negative effects on many aquatic ecosystems.  Streams, rivers, wetlands, and lakes in the western mountains and northern Plains are most likely to be affected, because these systems are strongly influenced by spring snowmelt and warming will cause runoff to occur earlier in winter months.

4.   Wetland loss in boreal regions of Alaska and Canada is likely to result in additional releases of CO2 into the atmosphere.  Models and empirical studies suggest that global warming will cause the melting of permafrost in northern wetlands. The subsequent drying of these boreal peatlands will cause the organic carbon stored in peat to be released to the atmosphere as CO2 and possibly methane.

5.   Coastal wetlands are particularly vulnerable to sea-level rise associated with increasing global temperatures.  Inundation of coastal wetlands by rising sea levels threatens wetland plants. For many of these systems to persist, a continued input of suspended sediment from inflowing streams and rivers is required to allow for soil accretion.

6.   Most specific ecological responses to climate change cannot be predicted, because new combinations of native and non-native species will interact in novel situations. Such novel interactions may compromise the reliability with which ecosystem goods and services are provided by aquatic and wetland ecosystems.

7.   Increased water temperatures and seasonally reduced streamflows will alter many ecosystem processes with potential direct societal costs.  For example, warmer waters, in combination with high nutrient runoff, are likely to increase the frequency and extent of nuisance algal blooms, thereby reducing water quality and posing potential health problems.

8.   The manner in which humans adapt to a changing climate will greatly influence the future status of inland freshwater and coastal wetland ecosystems.  Minimizing the adverse impacts of human activities through policies that promote more science-based management of aquatic resources is the most successful path to continued health and sustainability of these ecosystems. Management priorities should include providing aquatic resources with adequate water quality and amounts at appropriate times, reducing nutrient loads, and limiting the spread of exotic species.

Overall, these conclusions indicate climate change is a significant threat to the species composition and function of aquatic ecosystems in the United States. However, critical uncertainties exist regarding the manner in which specific species and whole ecosystems will respond to climate change. These arise both from uncertainties about how regional climate will change and how complex ecological systems will respond. Indeed, as climate change alters ecosystem productivity and species composition, many unforeseen ecological changes are expected that may threaten the goods and services these systems provide to humans.

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Law of The Marine Environment

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Overview of Algae Phytoplankton: Characterisation, History, Application

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A Study on The Purpose of Marine Biology and The Effect of The Ocean Phenomena on Aquatic Animals

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In the Ocean, It’s Snowing Microplastics

Tiny bits of plastic have infiltrated the deep sea’s main food source and could alter the ocean’s role in one of Earth’s ancient cooling processes, scientists say.

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By Sabrina Imbler

• April 3, 2022

As long as there has been marine life, there has been marine snow — a ceaseless drizzle of death and waste sinking from the surface into the depths of the sea.

The snow begins as motes, which aggregate into dense, flocculent flakes that gradually sink and drift past the mouths (and mouth-like apparatuses) of scavengers farther down. But even marine snow that is devoured will most likely be snowfall once more; a squid’s guts are just a rest stop on this long passage to the deep.

Although the term may suggest wintry whites, marine snow is mostly brownish or grayish, comprising mostly dead things. For eons, the debris has contained the same things — flecks from plant and animal carcasses, feces, mucus, dust, microbes, viruses — and transported the ocean’s carbon to be stored on the seafloor. Increasingly, however, marine snowfall is being infiltrated by microplastics: fibers and fragments of polyamide, polyethylene and polyethylene terephthalate. And this fauxfall appears to be altering our planet’s ancient cooling process.

Every year, tens of millions of tons of plastic enter Earth’s oceans. Scientists initially assumed that the material was destined to float in garbage patches and gyres, but surface surveys have accounted for only about one percent of the ocean’s estimated plastic. A recent model found that 99.8 percent of plastic that entered the ocean since 1950 had sunk below the first few hundred feet of the ocean. Scientists have found 10,000 times more microplastics on the seafloor than in contaminated surface waters.

Marine snow, one of the primary pathways connecting the surface and the deep, appears to be helping the plastics sink. And scientists have only begun to untangle how these materials interfere with deep-sea food webs and the ocean’s natural carbon cycles.

“It’s not just that marine snow transports plastics or aggregates with plastic,” Luisa Galgani, a researcher at Florida Atlantic University, said. “It’s that they can help each other get to the deep ocean.”

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10 Ways You Can Help Save The Oceans

Oceans cover more than 70% of the planet and are home to important species and ecosystems that we rely on for food, livelihoods, climate regulation and more. but the oceans need our help..

Saving the oceans can sometimes feel like an overwhelming task, but if we all pitch in, we can make a big difference. While there are a variety of lifestyle choices that, when adopted, can help the oceans, here are our top 10 ways you can help save the oceans! 

10 WAYS YOU CAN HELP SAVE THE OCEANS 

Demand plastic-free alternatives .

The oceans face a massive and growing threat from plastics. An estimated 33 billion pounds of plastic pollution flood our marine environment from land-based sources every year — that’s roughly equivalent to dumping two garbage trucks full of plastic into our oceans every minute. And, instead of degrading, plastic breaks up into smaller and smaller pieces that are swallowed by everything from fish and sea turtles to seals and seabirds, many of which are endangered! 

We must urge government leaders to pass policies that reduce plastic production and require companies to phase out unnecessary single-use plastic products and ramp up reusable and refillable options. You can add your name to call on world leaders to tackle plastic pollution . 

REDUCE YOUR CARBON FOOTPRINT 

The climate crisis threatens the health of our oceans and the marine wildlife that call them home. Sea levels are rising, and we are experiencing more extreme weather globally, and carbon dioxide – a known greenhouse gas – is making our oceans more acidic. This acidity contributes to the loss of corals, or coral bleaching.  

The climate crisis is something we know how to combat – by drastically reducing greenhouse gas emissions. Join Oceana by pledging to combat climate change and reduce your carbon footprint. 

EAT RESPONSIBLY-SOURCED SEAFOOD 

Choose seafood that is healthy for you and the oceans from well-managed, wild fisheries. Wild seafood is a renewable resource that requires minimal freshwater to produce and emits less carbon dioxide than land-based proteins like beef. We know it’s hard to know what fish are okay to eat, which is why you can turn to these helpful resources: 

• Print or download a guide from Seafood Watch to help you make sustainable choices when you buy or order seafood. 
• Refer to these top chefs for sustainable seafood recipes . 
• Consider adding small, oily fish that are packed with protein to your diet. 

VOTE ON OCEAN ISSUES 

Electing public officials that support smart ocean policies can help us protect marine life and our oceans. Do your research on candidates and make an informed decision, then exercise your right (and responsibility) to vote. And don’t let Election Day be the last time they hear from you. Follow up with your candidates and elected officials regularly to remind them of policies you care about. 

CONTACT YOUR REPRESENTATIVES AND LAWMAKERS

Your representatives and lawmakers might not know how important these issues are that face our oceans. But they will if you tell them. It’s up to constituents like you to make lawmakers aware of the crises facing marine life and our oceans. Don’t be shy! Take action with Oceana to directly contact your government representatives and lawmakers.    

TEACH KIDS ABOUT THE OCEANS AND THE ENVIRONMENT

Around the world, research has shown that children have limited knowledge about the oceans because marine science topics are absent in most school curricula. The oceans are critical to life on Earth. Understanding that at an early age can help kids form connections with the seas and understand the reasons why it’s so important to protect them. Check out the Kids Environmental Lesson Plans (KELP) from Sailors for the Sea and dive into Oceana’s Marine Life Encyclopedia to learn about our oceans and all animals that inhabit them.  

AVOID OCEAN-HARMING PRODUCTS

There are many products directly linked to harming endangered or threatened species, unsustainable fishing methods and pollution. For example, avoid cosmetics that contain shark squalene, jewelry made of coral or sea turtle shell, souvenir shells of conchs, nautiluses and other animals, and single-use plastics like straws and water bottles that can end up in our oceans. These products can threaten important species and ecosystems.  

LEAVE NOTHING BEHIND

As beach crowds increase, so does the amount of trash left behind or blown away. Don’t let your day outside contribute to the destruction of our oceans. Remember to leave nothing behind but your footprints — collect and properly dispose of your trash.  

SHARE YOUR OCEAN EFFORTS WITH FRIENDS, FAMILY, AND COWORKERS

Tell people what’s going on with the world’s oceans and what they can do to join you in making a difference. Spread the word about petitions, share fun facts, and join the conversation with us on Facebook , Instagram , X (formerly Twitter), TikTok , and YouTube . 

BECOME AN OCEAN ADVOCATE 

More than 1 million members and activists in over 200 countries have already joined Oceana – the largest international organization dedicated solely to ocean conservation. Together, we’ve won over 300 victories and protected nearly 4 million square miles (10 million square kilometers) of ocean. But there’s more to be done!  As a Wavemaker, your support is critical to our victories and protecting the world’s oceans and we can’t do it without you.    

MAKE A DONATION

We’ve already protected nearly 4 million square miles of ocean and innumerable sea life – but there is still more to be done. Donate today to turn the tide for our oceans!

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Essay on Aquatic Animals (510 Words)

Aquatic lives are much different than normal terrestrial lives. Aquatic animals are those that live inside water. They have a provision in body to make their respiration. These aquatic animals are especially characterized as the one who don’t get a close contact with the world outside water.

Fish is one good example of aquatic animal. There are many types of aquatic animals. If these animals are in contact with the outer world in the absence of water they can not breathe they die every soon within few minutes. Fish consumes oxygen from inside the water molecules. They can not breathe oxygen normally from the outside air.

Many people use fish as their food, but this aquatic animal life is in danger because of continuous decline in their population.

Image Source: upload.wikimedia.org

There are many factors that cause harm to the aquatic animal’s life. One main reason is the water pollution. Man is the only intelligent animal on earth blessed with the ability to think rationally. But this man has disturbed the life cycle of aquatic animals because of his indiscriminate activities. Many manufacturing companies spread their chemicals, wastages and experimental products inside water.

This pollutes the water which is home to the aquatic life. As a result, fishes are unable to breathe even inside water. Polluted water lacks oxygen inside and thus many fishes die even inside water. It is necessary to think on this issue as the aquatic animals and their life are in danger because of man’s mistakes.

Aquatic animals involve not only fishes but many other animals. There are many types of snakes also that live inside water. These snakes are also a part of aquatic life. These snakes can be categorized as the aquatic animal. Apart from snakes there are many types of turtles. But turtles, crocodiles and frogs are amphibians that can live inside water as well as on ground because they have got provision inside their body to be able to breathe both inside water as well as on ground.

It is responsibility of every human being to take care of aquatic animal and their lives. These species are depleting day by day. If this decline is not stopped right away, soon they will vanish completely.

Aquariums play an important role in this regard. These aquariums are designed to sustain aquatic lives. Aquatic animals are limited and if they also get depleted, the next generation might not see them. So it is necessary to take quick actions against the extinction of aquatic animals.

Aquatic animals and their life vary to a great extent than terrestrial animals. If these animals are not preserved properly, they will not persist in near future and this will directly affect the entire life cycle of this world. The basis of entire food chain of this world is supported by these aquatic animals; if their lives get disturbed then for sure food chain will get affected adversely.

Therefore it is necessary to take good care of aquatic animals and their lives, this will maintain a balance of overall life cycle of living beings.

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