About 20% of Florida’s historical mangrove habitat has been lost to human impacts. Mangroves in urban areas like Tampa, Marco Island, the Keys and Dade County have suffered the greatest loses. While some of the loss is the result of direct removal, oils, sediments, hydrological modifications and boat waves can be just as destructive.
The above ground roots of mangroves are essential adaptations to harsh natural conditions. However, they also expose mangroves to harmful human influences. The tiny lenticels that must “breath” for the flooded roots are highly susceptible to clogging from oils and fine sediments. Oil spills will kill much of the invertebrate community within a few days and many of the mangroves will die in a few weeks. Mangroves may continue to die for a year after the spill. Fine particles from dredging, sugar and pulp mill wastes will also choke out the oxygen supply and kill mangroves.
Diking that continually submerges prop roots and pneumatophores will drown and kill mangroves. Draining will allow other species to invade mangrove habitat. Blocking the flushing of tidal flows can result in stressful stagnant conditions. Reestablishing the proper hydrology is the single most important factor for successful restoration of mangroves. However, restoration of mangrove ecosystems can cost more than $50,000 per acre and take decades. Protection is the best policy.
Environmental factors and adaptations