While total mangrove losses do not appear as significant as those of some other Florida ecosystems, the losses in a number of areas have been sizable. Mangroves are especially vulnerable to pollution, including petroleum and some kinds of man-made sediments, because the pores in their root systems can easily become clogged. Some varieties are extremely sensitive to herbicides. The trees are also affected by changes in freshwater frequency and flows caused by human activities elsewhere. In Florida Bay, many mangrove islands are dying, probably because freshwater flows from Lake Okeechobee that once diluted the bay's salinity have been diverted for agricultural and urban use.
Red mangroves appear to be especially at risk.
Mangrove pruning continues to cause habitat deterioration. Recent research by DNR shows that pruned red mangroves grow fewer prop roots and fruits and thus provide lower quality habitat. Because it weakens the trees, pruning diminishes shoreline protection, and it also appears to reduce the number of bird species using the habitat. In recent years mangrove swamps have been given legal protection because we increasingly understand their environmental importance. Where mangrove swamps have been destroyed, fish and shellfish populations have seriously declined.