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The Mangrove's of Broome The Mangrove walk mapped out by Paul Faulkes has been instrumental in the preservation and understanding of the Mengal system. Clearing of the mangroves has caused erosion of the foreshore of Roebuck Bay, further reducing the capacity of the environment to filter out the pollution caused by the creation of a foreshore settlement. The walk and the information put together will broaden the knowledge of visitors into Broome, helping with the ecological preservation of the surrounding area.
Due to Broome's harsh, tropical and semi-arid environmental conditions, it is a host to 11 of the 17 species of Mangroves in Australia, and of 60-70 species in the world. Mangroves are trees or bushes that usually grow between the high tides and mean sea levels. The term Mangrove refers to the individual trees and species, while the Mangrove plant community is called a Mangal. Broome supplies the four basic requirements for growth: 1. Warm climate where the average temperature of the coldest month is above 20 Degrees Celsius. 2. Protected shore wave action and strong tides erode established Mangals and hinder the development of seedlings. 3. Salt water because mangroves are salt water specialists they can compete with other terrestrial plants more successfully in saline environments (some grow in fresh water) 4. Tides most Mangals require tidal inundation. Optimum conditions exist where the shoreline is gently shelving and the tide range is large.
The most remarkable feature of the mangrove is its outstanding ability to grow and thrive in sea water. Mangroves have a number of ways of coping with salt: 1.Mangroves can tolerate higher internal salt concentrations in their sap than most other terrestrial plants. 2.Mangroves remove salt by storing it in older leaves before they fall. That is why older leaves are so succulent. 3.Depending on the species, mangroves reduce the accumulation of salt using their roots and leaves to actively exuding the salt or secreting it. Species such as Avicennia marina, Aegialitis annulata and Aegiceras corniculatum, salt is removed by special glands in the leaves. These mangroves are known as "salt secretors". The roots of the mangroves in the Rhizophora and Sonneratia family are specially adapted to prevent as much salt as possible from entering the plant. These mangroves are known as "salt excluders".
There are a number of distinctive habitats. The major and most common types of animals living in the mangroves are: - Creeks and channels: Fish, crabs, saltwater crocodiles - Semi-permanent pools: Mud skippers - Soil surface: Hermit crabs, mud whelks, marine snails - Within the soil: Mud crabs, mud skippers, shrimps, worms - Mangrove trunks and root systems: mEncrusting oysters, barnacles, snails, shipworm - The tree canopy: Birds, insects, bats At high tide many fish and crustucea move into the mangroves to feed in the nutrient rich environment. At low tide wading birds, reptiles can be common.
Animals play an important role in the mangals: - Nectar feeding birds and insects pollinate the mangrove flowers. - Crabs, mudskippers and other burrowing animals help aerate and improve the soil by turning it over. - Crabs, insects and feeding on fallen leaves assist to break down the vegetable matter making it available to other animals such as fish.
Mangroves are the most important link in the food chain of coastal environments. They protect and reclaim the foreshore and are also an important nursery for fish and crustaceans. The plant matter dropping is rich in nutrient that supports a diverse range of animals from bacteria and funghi to crustacean which in turn provide food for larger animals. The protection provided by the roots of the trees provide ideal nursery conditions for many crustaceans, molluscs and fish.
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