Threats

Shrimp Farming

By far the greatest threat to the world's mangrove forests is the rapidly expanding shrimp aquaculture industry. Hundreds of thousands of acres of lush wetlands have been cleared to make room for artificial ponds that are densely stocked with shrimp. Shrimp farmers dig channels to supply the ponds with enormous quantities of freshwater and seawater. These water diversions alter the natural flow of water that maintains the health of surrounding mangroves as well as ecosystems farther inland and offshore. Diverting water can harm mangroves by preventing their seeds from being dispersed via seawater, and it can kill the trees by cutting off freshwater supplies. When diverted inland, seawater may contaminate farmland or freshwater below the ground. Shrimp farmers also use massive amounts of chemicals and antibiotics to keep the overcrowded shrimp healthy. This chemical soup, along with enormous quantities of organic waste, contaminate surrounding freshwater and coastal waters. 

Tourism

Tourism is a booming industry and an important source of income in many developing nations. Unfortunately, irresponsible tourism can destroy the very resources people are coming to see. As tourists hike, drive, or paddle into once-remote areas, they bring with them garbage, sewage, noise, fumes, lights, and other disturbances that can damage mangroves and the surrounding ecosystems. Walking off paths, lighting fires, feeding wildlife, anchoring on reefs, and collecting shells and plants are also destructive.

Agriculture

Many thousands of acres of mangrove forest have been destroyed to make way for rice paddies, rubber trees, palm oil plantations, and other forms of agriculture. Farmers often use fertilizers and chemicals, and runoff containing these pollutants makes its way into water supplies. Despite their resilience, mangroves can tolerate only a limited amount of industrial and agricultural pollution without dying. 

Coastal Development

Coastal development takes many forms, from ports and docks to hotels, golf courses, marinas, and convention halls. Everyone loves being near the sea, but as streams and wetlands are filled by roads and concrete, they can no longer process natural chemicals. Worse still, pollutants that accompany development can damage individual trees or whole tracts of mangroves. 

Charcoal and Lumber Industries

Chopping down mangroves for charcoal and timber is an important cottage industry for many coastal communities. Mangrove wood is used for building material, fencing, and fuel. It also yields valuable, high-quality charcoal.


Reference : http://www.amnh.org/explore/science-bulletins/bio/documentaries/mangroves-the-roots-of-the-sea/mangrove-threats-and-solutions