Marine coastal ecosystem

The land meets the sea at the coast.

This area is a very busy place. Many different animals live here.

Some places are where rivers meet the ocean.

These areas are called estuaries. They are homes for birds and fish.

Other places have many plants. Some have trees that grow in salt water. Some have grass under the sea.

Coral reefs are also found near the coast. These reefs are made of tiny animals. They give food and homes to many sea creatures.

These places help keep our water clean. They also help keep the land safe from big storms.

The coast is where the land meets the ocean.

These areas cover about 7 percent of the ocean surface. They are very busy places with many different living things.

Some coasts have special water. Estuaries happen where rivers meet the sea. The water there is brackish. This means it is a mix of fresh and salt water.

Many fish and birds live in these areas.

Other coasts have many plants. Mangrove forests have trees that live in salt water.

Seagrass meadows are like underwater grasslands. They provide food for sea turtles and crabs.

Coral reefs are also found in warm, shallow water. They are made of tiny animals called coral polyps. These polyps make hard skeletons. Over time, these skeletons build up to make big structures. These reefs give food and homes to many sea creatures.

Coastal areas help humans, too. They can clean the water by filtering pollutants. They also protect the land from big storms.

Many people live close to the coast. We must work to keep these places healthy.

The coast is a busy place where the land meets the ocean.

These areas sit along the edges of continental shelves. They cover about 7 percent of the ocean's surface area. These places are full of life and energy. They are called marine coastal ecosystems. They matter because they support many different types of living things. These systems help keep our planet healthy by moving nutrients around.

Many different habitats work in different ways along the coast.

In estuaries, freshwater from rivers meets salty ocean water. This creates brackish water, which is a mix of both types. Salt marshes use special plants like cordgrass to grow in wet areas. In tropical places, mangrove forests use salt-tolerant trees to create homes. Warm, shallow waters might have seagrass meadows that act like underwater grasslands. Even colder waters have kelp forests made of tall seaweed.

Some of these habitats are built by tiny animals.

Coral reefs are made of colonies of tiny animals called coral polyps. These polyps create hard skeletons made of calcium carbonate. As more polyps live and die, these skeletons build up into huge structures. These reefs can become some of the most diverse places on Earth. They provide food and shelter for a huge range of marine life. The Great Barrier Reef is one of the largest examples of this.

Coastal ecosystems provide many important services for humans.

They help clean the water by filtering out pollutants. They also soak up carbon to help against climate change. These areas act like a shield to protect the land from big storms. They also stop erosion, which is when land washes away. Many people rely on these areas for fishing and tourism. In fact, over half of the world's population lives within 200km of a coast.

These special places are facing many hard jobs today.

Pollution and overfishing can hurt the balance of life. Climate change is also causing problems like rising sea levels. Ocean acidification and stronger storms can damage reefs and forests. To help, the United Nations created goals for the year 2030. They want to protect life below water and use resources wisely. There are also efforts to create protected areas to help nature heal.

Marine coastal ecosystems are complex biological systems located where the land meets the ocean.

These environments exist along the margins of the continental shelves. They occupy approximately 7 percent of the total ocean surface area. These regions are defined by high levels of biodiversity and productivity. This means they support a vast number of different species and produce a lot of biological energy. Because they sit at the boundary of two worlds, they facilitate the movement of nutrients and elements. They also act as a natural buffer for the planet by sequestering carbon.

One of the most important areas is the intertidal zone. This is the part of the coast that is exposed to air during low tide and covered by saltwater during high tide. Scientists divide this zone into four distinct physical sections. The spray zone is a damp area only reached by high tides or storms. The high intertidal zone is submerged at high tide but stays dry for long periods in between. This area is home to resilient wildlife like barnacles, mussels, and hermit crabs. The middle intertidal zone experiences tides twice a day and holds more variety. Finally, the low intertidal zone is submerged most of the time, allowing life to be more abundant.

Estuaries represent another vital habitat type. These occur where freshwater from rivers meets the saltwater of the ocean. This meeting creates brackish water, which is a specific mixture of fresh and salt water. Estuaries are extremely productive and serve as economic hubs for many human communities. In fact, 22 of the 32 largest cities in the world are located on estuaries. These ecosystems provide essential services like water filtration, erosion control, and nutrient cycling. They also act as crucial nurseries for many species of fish and shellfish.

Vegetated coastal ecosystems are found in various climates around the globe.

Mangrove forests are found in tropical or subtropical intertidal zones. They consist of salt-tolerant trees that protect habitats for crabs, shrimp, and fish. Salt marshes are coastal wetlands found in temperate and high-latitude areas. They are populated by plants like cordgrass that can handle salt. Seagrass meadows are underwater grasslands made of flowering plants. These meadows provide food and shelter for sea turtles and dugongs. In colder, nutrient-rich waters, kelp forests dominate. These are made of large brown algae that grow several meters tall to create dense underwater forests.

Coral reefs are among the most famous and diverse ecosystems on Earth. They are built by colonies of tiny animals called coral polyps. These polyps secrete hard calcium carbonate skeletons over long periods. As these skeletons accumulate, they create massive and complex underwater structures. These reefs thrive in high-energy shorelines where waves agitate the water. While they are highly productive, they are also very vulnerable to global warming. Marine heatwaves can cause a decline in these structures and the life they support. The Great Barrier Reef is a notable example of this massive ecosystem.

Lagoons provide a different type of coastal habitat. These are bodies of water separated from the larger ocean by natural barriers like sandbars or coral reefs. There are two main types: coastal lagoons and atoll lagoons. Coastal lagoons are separated by a simple barrier, while atoll lagoons are surrounded by circular coral reefs. Most lagoons are quite shallow, meaning they are heavily affected by wind and evaporation. This causes the salinity and temperature to vary widely. Lagoons are found on every continent except Antarctica. They support diverse species including birds, fish, and plankton.

Human activity creates significant pressure on these delicate systems. Over half of the world's population lives within 200km of a coastline. This proximity makes humans very susceptible to the changes in these ecosystems. Anthropogenic pressures, which are caused by humans, include pollution, overfishing, and coastal development. Climate change introduces further risks through sea level rises and ocean acidification. These changes can shift the entire ecological baseline of a region. To combat this, the United Nations established 17 Sustainable Development Goals in 2015. Their 14th goal, "Life Below Water," aims to conserve and sustainably use marine resources by 2030.