Naturalists have long struggled to define, in proper ecological terms, the environment of a mangrove swamp
Mangrove trees are able either to exclude or to excrete salt from their tissues.
Mangrove communities develop only near the sea because they cannot compete successfully with freshwater flora.
Mangroves are also limited by a need for rather balmy conditions.
Mangrove swamps typically fall within one of two broad categories of classification: mainland or oceanic island.
A salty habitat is not strictly required for growth, mangrove communities develop only near the sea because they cannot compete successfully with freshwater flora.
Mainland mangroves must usually cope with a pronounced variation in salinity across their width. This situation is quite distinct from that of oceanic-island mangroves, which form on shallow banks or in lagoonal areas well separated from the mainland.
Conversely, some coral islands in the central Pacific lack an accompanying fringe of mangroves, apparently because the floating propagules that serve as seeds for these trees cannot reach such remote isles.
The mangroves of Twin Cays belong to the oceanic-island type
Several “vibracores” indicated that the mangroves at Twin Cays did not begin growing on coral.
The community established itself some 7,000 years ago on what was then just elevated ground.
Submerged excavations indicate that strong currents must have flowed freely through the passage before an unrecorded tempest deposited enough sediment to dam one end of the channel
First black mangrove,Avicennia germinans,and then white mangrove Laguncularia racemosa mark zones of shallow floodwater and extended mudflats that develop as the tide moves in and out.
Hypersaline conditions in the upper reaches of the intertidal zone favor black mangrove seedlings because that species has the greatest tolerance for salt.
There are two broad categories of mangroves mainland and oceanic island. There also different types of mangroves red, black and white mangroves. All three are different from each other. Red mangroves live in the deepest salt water going from a few inches to over a foot deep.They have large prop-rootsoften times called "walking roots", with thick lenticels for gas exchange.Referred as "red" mangrove because they produce chemicals called tannins that turn the water and mud a rusty color. Its leaves are broadly-elliptical and the largest of the three about 3 to 5 inches long.Black mangroves,live in a few inches of salt water, furtherinland than the red mangroves. They can withstand higher levels of salt. They have pneumatophores, straw-like roots that stick out vertically from the mud for gas exchange. Referred as "black" mangrove because the older sections of the trunk and heartwood are blackish in color. Its leaves are narrow-elliptical and are about 2 to 4 inches long. The leaves have salt crystals formed on the top side; this is an adaption to living in high salt concentrations.White mangroves, live farthest away from the water of the three, just above the water level that the black mangrove lives in. Sometimes have pneumatophores but they are usually less common. When pneumatophores are present they are usually less prominent than on the black.Referred as "white" mangroves because of the whitish appearance of the bark.Its leaves are rounded elliptical, have two small glands at leaf base, and are more-yellow green in color. Viviparous propagules can survive in salt water for at least 1 month.
This article has help me understand the role mangroves play in ecosystems. I have no idea there were two different mangroves the mainland and the oceanic island. Mangroves are very different depending on the water level they are living. Its very sad that mangroves in the United States are disappearing. I think we should focus bit more on the environment than focusing on how to exploit natural resources. If we don't do that we might lose something very valuable. Mangroves are very valuable and we should protect them.