Other unique environments, such as those hosting submarine seep and vent biologic communities, are relatively unknown but potentially important. Coastal wetlands, a fragile transitional zone between marine and terrestrial environments, have significant economic and intrinsic ecological value. They are the most productive ecosystems known, providing nutrients and habitats that support the entire coastal ecosystem. Eighty percent of the Nation's coastal commercial and recreational fisheries depend upon wetlands for spawning, hatching, and nursery activities. Coastal wetlands also play vital roles as habitats for wildlife, waterfowl, and migratory birds.
Wetlands function to filter pollutants and to hold and absorb water, which can reduce flood peaks.
These systems generally overlie porous and permeable limestone, providing pathways for the movement of toxic and nutrient-rich ground water. Additional detrimental effects may be caused as well by increased turbidity due to anthropogenic activity and by increased salinity due to poor water management practices. Projects that are part of the South Florida Ecosystem Program are denoted by , and will open in a separate window. Eleven National Marine Sanctuaries have been designated and five additional ones proposed. For effective management, most of them require a multidisciplinary scientific program which evaluates present environmental conditions and describes the processes and rates of change.