Answer:
Human activities are the leading causes for Mangrove destruction. A great deal of mangrove forests are being "converted" (destroyed and replaced) due to development for aquaculture (raising aquatic animals for humane resources). Raising populations means raising food demand; shrimp, tilapia, and salmon are common aquaculture "products". It's estimated that shrimp farming alone has resulted in over 1/4 of mangrove destruction.
Lumber and demand for wood products is another threat. Millions of acres of mangrove forest are cut down each year to supply papermills.
Mangroves are a biodiversity "hotspots" and very valuable to the world's ecological well-being.
The best thing we can do as individuals to help is eat less fish products (to avoid supporting the development and destruction of forests) and use less paper products.