Ocean Breathing

INTRODUCTION

The ocean is not one ecosystem. It is a vast network of interconnected habitats ranging from sunlit coral reefs and coastal wetlands to the open ocean, polar seas and the deepest parts of the seafloor.

Within these environments lives an extraordinary diversity of organisms. Microscopic plankton, seagrasses, corals, molluscs, crustaceans, fish, sharks, seabirds, turtles and marine mammals all form parts of complex ecological networks.

Biodiversity is more than the number of species in the ocean. It also includes genetic diversity within species and the diversity of habitats and ecosystems that allow marine life to survive, reproduce and adapt.

Every organism interacts with others through food webs, competition, predation, migration and habitat formation. Some species create entire ecosystems: corals build reefs, mangroves create coastal nurseries, seagrasses form underwater meadows and kelp forests provide three-dimensional habitat for marine communities.

When biodiversity declines, these relationships can weaken. Protecting marine biodiversity therefore means protecting not only individual species, but also the ecological connections that keep ocean ecosystems functioning.

WHY IT MATTERS

Biodiversity helps ecosystems function. Different species perform different ecological roles, from producing food and recycling nutrients to controlling populations and creating habitat.

Marine ecosystems support human societies. Fisheries, tourism, coastal livelihoods and many cultural traditions depend on healthy marine ecosystems.

Healthy habitats support fisheries. Mangroves, seagrass meadows, coral reefs, estuaries and other coastal environments provide nursery, feeding and shelter areas for many marine species.

Biodiversity can strengthen resilience. Ecosystems containing diverse species and ecological functions can have greater capacity to respond to disturbances and environmental change.

Marine organisms contribute to planetary processes. Ocean life influences nutrient cycles, carbon movement, food webs and the exchange of matter between the atmosphere, surface ocean and deep sea.

Losses can spread through food webs. Removing predators, habitat-forming organisms or important prey species can produce ecological effects far beyond the species directly affected.

Protecting biodiversity is therefore not simply about preventing extinction. It is about maintaining the living systems that allow the ocean to function.

KEY FACTS

The ocean covers about 71% of Earth’s surface and contains an enormous range of habitats, from tropical coastlines to ocean trenches thousands of metres deep.

Scientists have formally described hundreds of thousands of marine species, but the true number of species living in the ocean remains uncertain and many organisms have yet to be documented.

Coral reefs support at least 25% of marine species despite occupying only a very small proportion of the ocean floor.

Coastal habitats are disproportionately important. Mangroves, salt marshes, seagrass meadows, estuaries and reefs provide nursery and feeding grounds for numerous species.

Marine protected areas now cover only a fraction of the global ocean, and the level of actual protection and enforcement varies considerably among areas.

Biodiversity exists at several levels. Genetic diversity, species diversity and ecosystem diversity all contribute to the resilience and functioning of marine environments.

Much of the deep ocean remains poorly explored. New species and ecological relationships continue to be discovered as scientists gain access to previously understudied environments.

Main Threats

Climate change. Ocean warming, marine heatwaves, acidification, oxygen loss and changing currents are altering habitats and shifting where marine species can survive.

Overfishing. Removing organisms faster than populations can reproduce can reduce abundance, alter food webs and weaken ecosystem structure.

Habitat destruction. Bottom trawling, coastal development, dredging and destructive fishing practices can damage the physical environments marine species need.

Pollution. Plastics, chemicals, oil, wastewater and excess nutrients can affect organisms and degrade marine habitats.

Invasive species. Organisms transported beyond their natural ranges through shipping, aquaculture and other human activities can sometimes compete with, prey upon or displace native species.

Disease and ecological disturbance. Environmental stress can increase vulnerability to disease and contribute to rapid ecosystem changes.

Multiple pressures occurring together. A habitat affected simultaneously by warming, pollution, fishing and physical disturbance may have less capacity to recover than one experiencing a single pressure.

Biodiversity loss is therefore rarely caused by only one factor. Protecting marine ecosystems requires addressing several interacting pressures at the same time.

SOLUTIONS

Protect ecologically important areas. Well-designed and effectively managed marine protected areas can reduce direct human pressures and provide space for ecosystems and populations to recover.

Restore damaged habitats. Mangrove forests, seagrass meadows, oyster reefs, salt marshes and coral reefs can be restored where ecological conditions make recovery possible.

Manage fisheries sustainably. Science-based catch limits, habitat protection, reduced bycatch and effective enforcement can help maintain both fish populations and wider ecosystem function.

Protect ecological connectivity. Marine species move between habitats throughout their lives. Conservation should therefore connect spawning areas, nursery grounds, migration corridors and feeding habitats.

Reduce pollution at its source. Preventing plastics, chemicals, untreated wastewater and excessive nutrients from entering waterways protects ecosystems more effectively than relying solely on cleanup.

Address climate change. Long-term protection of marine biodiversity requires rapid reductions in greenhouse-gas emissions alongside local conservation measures.

Expand scientific monitoring. Satellites, environmental DNA, acoustic monitoring, autonomous vehicles and traditional field surveys can help scientists detect biodiversity change.

Work with local and Indigenous communities. Effective conservation can benefit from combining scientific research with long-standing knowledge of marine ecosystems and sustainable resource use.

Protect biodiversity beyond national waters. Because much of the ocean lies beyond national jurisdiction, international cooperation is essential for conserving migratory species and high-seas ecosystems.

WHAT YOU CAN DO

Choose seafood responsibly. Supporting well-managed fisheries can reduce pressure on vulnerable species, habitats and marine food webs.

Support marine protected areas. Strong protection requires public support, scientific planning, adequate funding, monitoring and enforcement.

Reduce pollution. Limiting unnecessary plastics, disposing of chemicals responsibly and reducing waste can help prevent pollutants from reaching waterways and marine habitats.

Reduce your climate impact. Climate change is increasingly reshaping marine ecosystems. Supporting cleaner energy and effective climate policy helps address one of the largest long-term threats to ocean biodiversity.

Respect marine wildlife. Keep appropriate distances from animals, avoid disturbing nesting and breeding sites and follow responsible wildlife-viewing guidelines.

Support habitat restoration. Local projects restoring wetlands, seagrasses, reefs and coastal habitats can provide tangible opportunities to improve biodiversity.

Participate in citizen science. Wildlife observations, beach surveys and biodiversity monitoring can contribute useful information when connected to well-designed scientific programs.

Support science and conservation organizations. Research, monitoring and long-term conservation require sustained funding and public engagement.

Remember that biodiversity is interconnected. Protecting one charismatic animal is valuable, but lasting conservation also requires protecting its prey, habitat and the wider ecosystem around it.

SOURCES

Convention on Biological Diversity — Marine and Coastal Biodiversity
International framework and scientific information concerning conservation and sustainable use of marine biodiversity.

Convention on Biological Diversity — Marine & Coastal Biodiversity

NOAA Ocean Service — How Much of the Ocean Have We Explored?
Background on ocean exploration and how much remains poorly observed and understood.

NOAA — Ocean Exploration

NOAA Fisheries — Ecosystems
Scientific information about marine ecosystems, habitats, fisheries and ecosystem-based management.

NOAA Fisheries — Ecosystems

UN Environment Programme — Marine and Coastal Ecosystems
Information on marine biodiversity, ecosystem degradation, conservation and restoration.

UNEP — Ocean, Seas and Coasts

IPBES — Global Assessment Report on Biodiversity and Ecosystem Services
Major international scientific assessment of biodiversity loss, ecosystem change and the drivers affecting nature.

IPBES — Global Assessment

IUCN Red List of Threatened Species
Global scientific resource for conservation status and extinction risk across thousands of species.

IUCN Red List

IPCC — Oceans and Coastal Ecosystems and Their Services
Assessment of climate-change impacts, risks, adaptation and vulnerability across ocean and coastal ecosystems.

IPCC — Oceans and Coastal Ecosystems

Marine Ecosystems & Biodiversity