Red Mangrove trees

Description:

Red Mangrove grows in sea or brackish water. It does not need land, instead it roots into the soft muck in shallow water. In order to survive, the tree has adaptations that include: thick waxy green leaves that lose little precious fresh water to evaporation, a multitude of aerial and submerged prop roots to anchor the plant in place and collect water-borne silt and debris to build soil beneath it, special provisions to transport oxygen from the aerial roots to the roots submerged and embedded in the anaerobic muck below, and a truly amazing way of dispersing its offspring such that they end up in a suitable environment to grow. The Red Mangrove bears viviparous seedlings. This means that the seeds germinate and begin to grow before the fruit is dropped from the tree. Upon maturity, the single seeded fruits sprout, grow 6 – 12 inches and appear as cylindrical pods. But they really are seedlings that consist mostly of a long tap root topped by a small bud. These unique seedlings are called propagules. If a propagule falls from the tree into shallow water, it will spear itself into the muck and grow there. If it is high tide or the water is naturally deeper the propagule will float horizontally, carried by the currents for upwards of a year, potentially over hundreds of miles. With time the root tip absorbs water, and pulls the propagule vertical. When it reaches shallow water it will root in. Brackish water will be absorbed faster than seawater, so the propagule is more likely to tip vertical near shore where the seedling must lodge if it is to survive. The stilted roots coupled with their unusual mechanism of dispersal give the appearance that the Red Mangroves are walking on water and advancing seaward over time.

Habitat:

Caye near Placencia, Belize.

Notes:

Belize is home to 4 different species of mangove, the red mangove (Rhizophora mangle), the black mangove (Avicennia germinans), the white mangrove (Laguncalaria racemosa), and the buttonwood (Conocarpus erectus). The red mangrove is most often found along the water on cayes and waterways and is easily identified by the long prop roots that support the plant. The black mangrove is usually found farther away from the water's edge and can be recognized by the small protrusions called pnuematophores that encircle the base of the tree on the ground. These pnuematophores help to facilitate gas exchange as do the long prop roots found on the red mangroves. The white mangrove and buttonwood species are generally located even further away from the edge of the water. Mangroves thrive in salty environments because they are able to obtain freshwater from saltwater. Some secrete excess salt through their leaves, others block absorption of salt at their roots. This ecosystem traps and cycles various organic materials, chemical elements, and important nutrients. Mangrove roots act not only as physical traps but provide attachment surfaces for various marine organisms. Many of these attached organisms filter water through their bodies and, in turn, trap and cycle nutrients. The relationship between mangroves and their associated marine life cannot be overemphasized. Mangroves provide protected nursery areas for fishes, crustaceans, and shellfish. They also provide food for a multitude of marine species such as snook, snapper, tarpon, jack, sheepshead, red drum, oyster, and shrimp. Florida's important recreational and commercial fisheries will drastically decline without healthy mangrove forests. Many animals find shelter either in the roots or branches of mangroves. Mangrove branches are rookeries, or nesting areas, for beautiful coastal birds such as brown pelicans and roseate spoonbills.