Wednesday, February 25, 2009
From the birds that roost in the leafy canopy to the crabs that scurry about the trunks and the sponges and barnacles that live on submerged "roots", it is easy to see that a variety of organisms call the mangrove habitat home.
Mangroves are trees that live at or near the water's edge in protected marine habitats. This means that, while you are likely to find mangroves along the calm banks of the IRL you won't find them on wave-beaten ocean shores.
There are several different types of mangrove trees in the IRL, and they are not very closely related to one another. So what makes a mangrove tree a mangrove tree?T ere are several features that all species of mangrove trees have in common: olerance to conditions of high soil salinity. Tolerance to submergence in water or waterlogged soil, and to low oxygen conditions. Reproduction by means of specialized seeds called "seedlings.
In the middle of a mangrove clump (called a "mangle"), the amount of salt in the soil can be up to three times the amount found in ocean water. This concentration of salt is due to repeated flooding of the soil, followed by evaporation of water, leaving the salt behind. Mangrove trees are adapted to survive in salty soils that would kill most other kinds of plants. This is one reason why mangrove trees can thrive in areas too harsh for other vegetation. Some species, like the black mangrove, actually get rid of excess salt by "sweating" it out of their leaves.
Have you ever gone snorkeling before? If you have, then you have something in common with the black mangrove tree. Black mangroves survive in water- logged soil by using special "root snorkels" called pneumatophores. These structures are covered with small holes called lenticils that allow the roots to breathe the same way a snorkel lets you breathe while underwater.
Most plants produce seeds which don't sprout until they are planted. Mangrove seeds are different because they actually start to grow into a new plant while they are still attached to the parent tree. We call these specialized seeds seedlings. The picture shows you what seedlings from a red mangrove tree look like.The reason mangroves use these special seedlings is that the head- start in growth it gives young mangroves allows them to quickly take root when they are deposited in a favorable growing area. Ordinary seeds would probably be washed away before they have a chance to start growing.
Some plants, like dandelions, disperse their seeds by means of the wind. Other plants, such as apple trees, rely on animals to help disperse their seeds. Unlike these plants, the seedlings of mangrove trees are carried away from the parent tree by water. The picture shows an underwater view of several floating red mangrove seedlings.
If and when the tides or currents transport the seedlings to an area suitable for growth, the young mangrove quickly roots itself and begins the next stage of its life. Here, you can see several newly arriving seedlings growing along with some slightly older trees.
There are many plant and animal species which live within the mangrove community and depend on this unique habitat for their continued existence. Some, like the mangrove tree crab shown here, live upon the emergent (out of water) portions of mangrove trees. Pelicans and other seabirds also roost in the canopies of mangrove trees. Often, they form large rookeries - nesting assemblages of adult birds and their offspring - during the breeding season.
Other species, such as theyoung mangrove snappers spend the first years of their lives living within the submerged tangle of mangrove roots. Here, these fish find an abundance of food to eat, while remaining protected from larger predators which inhabit more open waters. Submerged portions of mangrove trees also provide living space for organisms which require a hard surface on which to live. Mangrove trees are very important in the IRL because there is very little hard bottom. The picture shows some of the organisms commonly found on submerged mangrove roots, including algae, sponges, sea squirts and barnacles.
Now that we have discussed the various features which all mangroves share, let's take a closer look at the three most important mangrove species which occur along the IRL - the red, black and white mangroves. Click on each photograph to learn more about a particular species.
Red Mangrove - Rhizophora mangle
Black Mangrove - Avicenna germinans
White Mangrove - Laguncularia racemosa
Special thanks and acknowledgements to:
http://www.cartage.org.lb/en/themes/Sciences/BotanicalSciences/MostThreatened/MangroveHabitats/MangroveHabitats/MangroveHabitats.htmhttp://www.epa.govPosted by:
Abigail Lim, Nicole Lim and Angelyn Ong
living nature
4:30 AM
