Why do mangrove forests grow where rivers meet the sea?

Mangrove trees are specially adapted to intertidal zones, where water levels rise and fall twice a day and salinity can vary sharply. Their tangled roots stabilize mud, trap sediment, and help protect coastlines from erosion. Many mangroves also have aerial roots or salt-filtering systems that let them survive in harsh coastal conditions. Mangrove forests are found in tropical and subtropical regions around the world, including Southeast Asia, West Africa, and the Caribbean. They are ecologically important nurseries for fish, crabs, and shrimp.