Marine ecosystem

Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. They cover more than 70% of the surface of the Earth and contain over 97% of Earth's water supply. These ecosystems include many different zones, such as the oceanic zone where whales and sharks live, the benthic zone below the water, and the intertidal zone between high and low tides. Other areas include mudflats, seagrass meadows, mangroves, coral reefs, and kelp forests.

These ecosystems are home to many types of organisms, including brown algae, corals, echinoderms, and sharks. They provide important resources for humans, such as food and jobs for significant portions of the global population. However, they face threats from human uses of marine ecosystems, pollution in marine ecosystems, overfishing, and changes in ocean chemistry caused by climate change. Because of these challenges, the international community has made protecting marine ecosystems a key part of its efforts for sustainable development.

Types or locations

Marine coastal ecosystems

Main article: Marine coastal ecosystem

Coral reefs

Main article: Coral reef

Coral reefs are well-known parts of the ocean, with the largest being the Great Barrier Reef. These reefs are made of many coral animals living together. The corals have special relationships with other sea creatures around them.

Mangroves

Main article: Mangrove

Mangroves are trees or bushes that grow in muddy soil near coastlines in warm areas. They connect land and sea and have special ways to survive in salty water. Mangroves protect coasts and provide food for many sea animals. They also help keep the air clean by taking in carbon dioxide from the atmosphere.

Seagrass meadows

Main article: Seagrass meadows

Seagrasses form underwater fields that are very important for sea life. They give homes and food to many animals and help protect coastlines from big waves. Seagrasses also keep water clean and help slow down climate change by taking in carbon dioxide.

Kelp forests

Main article: Kelp forest

Kelp forests grow in cool coastal waters around the world. They give homes to many sea creatures and help scientists learn about nature. However, people sometimes harm kelp forests by taking too many fish or by changing the climate.

Estuaries

Main article: Estuaries

Estuaries are places where rivers meet the ocean, creating a mix of fresh and salty water. These areas are very important for many animals and plants and give many benefits to people, like clean water and places to fish.

Lagoons

Main article: Lagoons

Lagoons are areas of water separated from larger oceans by natural barriers like sand or coral. They can be shallow and change with weather and seasons. Lagoons are home to many different animals and plants and help protect coasts and support fishing.

Salt marsh

Main article: Salt marsh

Salt marshes are areas where fresh and salty water mix near the coast. They have special soil and plants that can survive in muddy, salty conditions. Salt marshes help protect shorelines and give homes to many sea animals.

Intertidal zones

Main article: Intertidal zone

Intertidal zones are areas that are underwater during high tide and dry during low tide. These zones have different parts, each with its own plants and animals that can survive changing water levels.

Ocean surface

Main article: Ocean surface ecosystem

The ocean's surface is a special place where the air meets the water. It is home to many floating plants and animals, like seaweed and small creatures. This area is important for many sea animals and helps connect different parts of the ocean.

Deep sea and sea floor

The deep sea and the sea floor make up most of the space where sea animals live. These areas are still being explored, and scientists are discovering new creatures all the time.

Large marine ecosystems

In 1984, the National Oceanic and Atmospheric Administration of the United States created the idea of large marine ecosystems to help protect ocean areas. These are big parts of the ocean with special features that support many plants and animals. There are 66 of these areas around the world, and they are very important for fishing and keeping the ocean healthy. People work together to manage these areas and make sure they stay safe for future generations.

Large marine ecosystems include:

• East Bering Sea
• Gulf of Alaska
• California Current
• Gulf of California
• Gulf of Mexico
• Southeast U.S. Continental Shelf
• Northeast U.S. Continental Shelf
• Scotian Shelf
• Newfoundland-Labrador Shelf
• Insular Pacific-Hawaiian
• Pacific Central-American Coastal
• Caribbean Sea
• Humboldt Current
• Patagonian Shelf
• South Brazil Shelf
• East Brazil Shelf
• North Brazil Shelf
• West Greenland Shelf
• East Greenland Shelf
• Barents Sea
• Norwegian Shelf
• North Sea
• Baltic Sea
• Celtic-Biscay Shelf
• Central Arctic
• Iberian Coastal
• Mediterranean Sea
• Canary Current
• Guinea Current
• Benguela Current
• Agulhas Current
• Somali Coastal Current
• Arabian Sea
• Red Sea
• Bay of Bengal
• Gulf of Thailand
• South China Sea
• Sulu-Celebes Sea
• Indonesian Sea
• North Australian Shelf
• Northeast Australian Shelf/Great Barrier Reef
• East-Central Australian Shelf
• Southeast Australian Shelf
• Southwest Australian Shelf
• West-Central Australian Shelf
• Northwest Australian Shelf
• New Zealand Shelf
• East China Sea
• Yellow Sea
• Kuroshio Current
• Sea of Japan
• Oyashio Current
• Sea of Okhotsk
• West Bering Sea
• Chukchi Sea
• Beaufort Sea
• East Siberian Sea
• Laptev Sea
• Kara Sea
• Iceland Shelf
• Faroe Plateau
• Antarctica
• Black Sea
• Hudson Bay
• Arctic Ocean
• Greenland Sea

Role in ecosystem services

Main article: Ecosystem services

Marine ecosystems help both nature and people in many ways. They help control the world's climate, are important for the water cycle, and support many different kinds of plants and animals. They also give us food and energy, and provide fun activities like swimming and visiting beaches. In business, they help support fishing, farming underwater plants and animals, getting oil and gas from the sea, and moving goods by ship.

Scientists measure how healthy a marine ecosystem is by looking at tiny animals in the water, how clear the water is, and how much plant life there is. They use special tools on ships and satellites to watch changes over time. They also study fish to learn about their health and how they live together with other sea creatures.

Threats

Further information: Ocean § Threats from human activities

Human exploitation and development

Many people live near the coast, which puts pressure on marine ecosystems. Human activities like fishing, building, and farming can harm these areas. For example, important habitats like mangroves and coral reefs are often damaged or lost. Overfishing is also a big problem, with fish populations decreasing over time. This affects not just the fish, but also the people who depend on them and can even impact the climate.

Pollution

Invasive species

See also: Invasive species

• Global aquarium trade
• Ballast water transport
• Aquaculture

Climate change

Main article: Effects of climate change on oceans

• Warming temperatures (see ocean heat content, sea surface temperature, and marine heat wave)
• Increased frequency/intensity of storms
• Ocean acidification
• Sea level rise

Society and culture

Global goals

Scientists work to help both nature and people by studying how to manage large water areas in smart and affordable ways. This helps protect the environment and support local economies.

The world has agreed on goals to protect ocean life, called Sustainable Development Goal 14 "Life Below Water." These goals aim to keep coastal areas healthy and help communities live in ways that don’t harm nature. The United Nations also started a special time from 2021 to 2030 to focus on fixing damaged ecosystems, but more work is needed to restore coastal areas.