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Unlock This CourseCoastal ecosystems are some of the most productive and diverse environments on Earth. They exist where land meets sea, creating unique conditions that support specialised plants and animals. These ecosystems provide vital services to humans, including coastal protection, fish nurseries and tourism opportunities.
Key Definitions:
Coastal ecosystems cover less than 2% of the ocean's surface but support over 25% of all marine species. They act as nurseries for fish, protect coastlines from storms and store huge amounts of carbon - making them crucial in fighting climate change.
There are several main types of coastal ecosystems, each adapted to specific environmental conditions. Understanding these helps us see why they're found in particular parts of the world.
Mangroves are salt-tolerant trees that grow in tropical and subtropical coastal areas. They have special adaptations like aerial roots and salt-filtering leaves that help them survive in salty, waterlogged conditions.
Between 30°N and 30°S latitude, in sheltered coastal areas with warm temperatures year-round.
Prop roots, pneumatophores (breathing roots) and salt-excreting leaves.
Fish nurseries, migratory birds, crocodiles and specialised crabs.
The Sundarbans, spanning Bangladesh and India, is the world's largest mangrove forest. It covers 10,000 km² and is home to the endangered Bengal tiger. This UNESCO World Heritage site demonstrates how mangroves can support both wildlife and human communities through fishing and tourism.
Coral reefs are underwater ecosystems built by tiny animals called coral polyps. They need warm, clear, shallow water to survive and are often called the "rainforests of the sea" due to their incredible biodiversity.
Coral reefs need water temperatures above 18°C, clear water for sunlight penetration and low pollution levels. They're found mainly between 30°N and 30°S latitude.
The distribution of coastal ecosystems isn't random - it's controlled by several key factors that determine where each type can survive and thrive.
Temperature and rainfall patterns are the most important factors controlling coastal ecosystem distribution. Different ecosystems have evolved to cope with specific climate conditions.
Mangroves and coral reefs need warm temperatures (above 18°C). Salt marshes can tolerate cooler conditions.
High rainfall creates freshwater input, affecting salinity levels. Some ecosystems need brackish water (mix of fresh and salt).
Seasonal changes in temperature and rainfall affect ecosystem productivity and species composition.
The shape of the coastline, tidal patterns and sediment supply all influence which ecosystems can develop in different locations.
Sheltered bays and estuaries favour mangroves and salt marshes, while exposed coasts with clear water suit coral reefs. Rocky shores support different communities than sandy beaches.
Looking at specific regions helps us understand how global patterns work in practice and see the variety of coastal ecosystems around the world.
The Great Barrier Reef stretches 2,300 km along Australia's northeast coast. It's the world's largest coral reef system, supporting over 1,500 fish species and 400 coral species. Its location in warm, clear tropical waters demonstrates perfect conditions for coral reef development.
Tropical coastlines host the most diverse coastal ecosystems due to warm temperatures and high solar energy input year-round.
Extensive coral reefs, mangrove forests and seagrass beds. High biodiversity but facing threats from tourism and climate change.
World's highest marine biodiversity. Coral triangle region with extensive mangroves and coral reefs supporting millions of people.
Mangroves along protected coastlines, coral reefs in clear waters. Important for local fishing communities and tourism.
Temperate coastlines have different ecosystems adapted to cooler temperatures and seasonal changes. These include salt marshes, seagrass beds and kelp forests.
Found in temperate regions with large tidal ranges. Important for coastal protection and bird migration. Examples include the Wadden Sea in Europe and San Francisco Bay in California.
Coastal ecosystems worldwide face increasing threats from human activities and climate change. Understanding these threats is crucial for conservation efforts.
Growing coastal populations put pressure on these fragile ecosystems through development, pollution and overuse of resources.
Hotels, ports and housing destroy habitat. Mangroves are often cleared for aquaculture ponds.
Agricultural runoff causes eutrophication. Plastic waste and chemicals harm marine life.
Removes key species, disrupting food webs. Destructive fishing methods damage coral reefs.
The Maldives experienced severe coral bleaching in 2016 when ocean temperatures rose 2°C above normal. Over 60% of corals died, showing how climate change threatens even well-protected reef systems. Recovery efforts include coral restoration and reducing local stressors.
Rising temperatures, sea levels and ocean acidity are changing coastal ecosystems faster than they can adapt.
Warmer water causes coral bleaching. More acidic oceans make it harder for corals and shellfish to build their skeletons. Sea level rise floods coastal habitats.
Protecting coastal ecosystems requires international cooperation and local action. Many countries are creating marine protected areas and sustainable management plans.
Some coastal ecosystems are recovering thanks to protection efforts and community involvement.
No-take zones allow ecosystems to recover. The Papahānaumokuākea Marine National Monument in Hawaii protects 1.5 million km² of ocean and has seen fish populations increase dramatically.