Worldwide there are about 65 recognised species of mangrove plants. Up to 39 mangrove species and hybrids are known to occur in Queensland, although figures can change as the definition of a mangrove is not clear.
These are the mangroves at Mark Road Russell Island, the east coast of Russell Island
Mangroves edge the island and are an unique feature of the Island Mudlands. The mangroves below are at Sandy Beach, the southern end of the island
Some wetland species (Avicennia integra, Avicennia marina var. australasica, Excoecaria agallocha var. agallocha, Excoecaria agallocha var. ovalis, Acanthus ebracteatus, Acanthus ebracteatus subsp. ebarbatus) are possibly found only in Australia while others occur widely throughout the Indo-West Pacific region.
The north-east coast of Australia is home to the greatest diversity of mangroves and associated plants. This region was close to the centre of origin and dispersal of mangroves. The climate is similar to that under which they first evolved, and the sheltered shallow waters of numerous estuaries are ideal for growth.
The distribution of mangroves has been mapped through the Queensland wetland mapping.
A teaspoon of mud from a north Queensland mangrove forest contains more than 10 billion bacteria. These densities are among the highest to be found in marine mud anywhere in the world and are an indication of the immensely high productivity of this coastal forest habitat.
A square meter of mangrove plants produces about 1kg of litter per year (mainly leaves, twigs, bark, fruit and flowers). Some of this is eaten by crabs, but most must be broken down by bacteria and fungi before the nutrients become available to other animals. Dividing sometimes every few minutes, bacteria feast on the litter, increasing its food value by reducing unusable carbohydrates and increasing the amount of protein—up to 4 times on a leaf that has been in seawater for a few months. Fish and prawns eat the partly decomposed leaf particles. They, in turn, produce waste which, along with the smallest mangrove debris, is taken up by molluscs and small crustaceans. Even dissolved substances are used by plankton or, if they land on the mud surface, are browsed by animals such as crabs and mud whelks.
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