Why and how are mangroves destroyed?

Over the past several decades, the total global area occupied by mangroves, almost half, has disappeared as a result of a variety of destructive human activities, including overharvesting, freshwater diversion, oil spills, herbicide and human waster runoff, and widespread dredging and clearing for development tourist resorts. Mangroves quite simply are being devastated by man and are disappearing at an alarming rate. In comparison, natural destruction of mangroves is relatively low compared to widespread human impacts. Mangroves are also commercially attacked as sources of durable and water resistant wood, medicine, tea, livestock feed and charcoal production. All of which however, are destructive also. One of the most damaging of man's activities towards mangrove forests is the rapidly expanding shrimp aquaculture. This practice poses a grave threat to the world's remaining mangroves. Thousands and thousands of hectares of lush mangrove forests have been destroyed to make room for artificial shrimp ponds which in addition to mangrove destruction are sources of intense coastal pollution.