Tolerant of saltwater, mangroves are represented by a wide variety of species that colonize tropical coasts across our planet. In the U.S., mangrove ecosystems are best developed along the Gulf Coast of southern Florida, from Tampa Bay to the Florida Keys.
Red mangrove shrubs are the vanguard of these coastal woodlands, forming the interface between water and land. Lining tidal streams, bays and inlets, these shrubs form dense thickets, easily recognized by the arching pattern of stilt-like roots that sprout from their lower trunks. These pioneer plants have adapted to their marine habitat by retaining fertilized seeds on their stems, where they germinate into small seedlings; released into the tidal waters, they float about until they encounter a sandbar or mudflat, where they quickly gain a foothold. Those not dislodged by storms or high waves grow rapidly and their tangle of roots trap sand, mud and organic debris; in doing so, the lone mangrove generates an island or peninsula as additional seedlings take root at their edge.
Just inland from the red mangroves is a band of black mangroves; also shrub-like, these trees are less tolerant of standing water and occupy sandy shores just above the high-tide line. Further inland are the white mangroves, which grow to heights of 30 feet in some areas. The ecosystem covered by these mangrove bands harbor a variety of wildlife, including wading birds that fish the shallows, raccoons that stalk the mudflats and mangrove crabs that climb the twisted branches; protecting tidal creeks from pounding waves, these evergreen woodlands also harbor vital nurseries for marine fish. Finally, mangrove islands are a favorite nesting site for brown pelicans, herons, anhingas and egrets, offering protection from land predators; unfortunately, the copious guano produced by these flocks will, in time, poison and kill the trees.
