[By Nathania Burrie]
[User: TaniaSmartTwit]
[March 2002]
Introduction
Coastal mud flats throughout the tropics carry a vegetation of mangrove swamp, which is particularly luxuriant in the wet tropics, such as Cairns itself. These evergreen trees and shrubs share similar habitat preferences, and a similar appearance to the untrained eye. This report will explain my findings in this biological topic, and describe the adaptations the mangroves have developed in order to survive the harsh location of estuaries and wetlands; the typical layout of mangrove communities through an original transect; representative specimen samples and descriptions; and also the typical state of the water and thus the environment through regular water samples.
Adaptations
The estuaries, salt marshes, swamps and wetlands mangroves live in represent hostile environments to mainland vegetation and have forced upon mangrove evolution a few peculiar adaptations such as tolerance of salty water, the development of pneumatophores ("breathing roots"), and a marked tendency to germinate their seeds on the tree. These features have consequently enabled mangroves to dominate the muddy coasts, leaving few competitors and only a small percentage of non-mangroves surviving in the harsh conditions, - most of the non-mangroves, as you will find, being part of the myrtle family.
Because of salt water and oxygen-deficient soil, many mangrove trees have roots growing above the ground. The names of these roots are: prop roots, buttress roots, pneumatophores or knee roots, and surface roots. These project above the mud and have small openings (lenticels) through which air penetrates and oxygen is absorbed through the spongy tissue to the roots beneath.
Estuaries and swamps impose very high water salinity. In fact salinity percentages can stand on average 3% 's - as high as seawater! For this purpose, mangroves have acquired three ways to survive with high and variable
Bibliography: ·Britannica Encyclopædia CD, 2001 ·Britannica Encyclopædia Vol VI, 1983 ·Webster 's Third New International Dictionary, G. & C. Merriam Co., 1976 Internet addresses: