The major coastal communities are mangrove forests, seagrass beds, lagoons and coral reefs, biologically and physically linked. About 300 species of coral, 1000 species of fish and 1200 species of mollusks are recognized in Micronesia. In the mangrove forests there are shrimps, crabs and fish, as well as birds that feed on them. Seagrass meadows appear offshore following the mangroves. The lagoons provide food for the reef inhabitants and contain various kinds of plankton. The biodiversity and complexity of the coral reefs increases markedly from east to west, with 150 species of hard coral at Kosrae, 200 at Pohnpei and 300 at Chuuk. Coral productivity in this area is among the highest in the world, absorbing about 2500 grams of carbon per square meter per year, against 2200 grams in the tropical forest and 125 grams in the open sea.