Thursday, July 5, 2012

Coral reefs and Mangrove Swamps

Coral reefs are found where the average annual temperature of the sea does not drop below 21.C. they are the richest of marine environments, estimated to contain one third of the world’s fish species and up to 500,000 animal species in all. Reef corals can only thrive in shallow water, so are often close to land, and therefore at special risk from human activities. Dangers include pollution; dredging and removal for construction purposes; damage by collection of coral and other invertebrates as tourist trophies; and collection of fish for the aquarist trade, which has already wiped out some species of colourful reef fish.

 Mangrove swamps occur in tropical regions where soft sediments are covered with sea water. In cooler areas salt marshes take their place. Both types of environment are rich in species. Mangrove swamps are the nurseries for many kinds of open water tropical fish; salt marshes are feeding grounds for the worlds migrating waders and water fowl. Yet both environments are regarded with disfavor by the majority of human kind and there has been greater destruction of mangrove swamps than of any other habitat type. Currently about 165, 000Km2 of mangrove forest remain, but almost all are under threat largely from pollution, which in some cases causes harmful mutations, and from expansion of farming.