Nearly half of Australia's mangrove forests are found in subtropical and tropical areas of coastal Queensland (44% of the continent's total), followed by the Northern Territory (37%) and Western Australia (17%).[1]
In Western Australia, mangroves are scattered along the coast; the mangroves of the Abrolhos Islands are 300 kilometres south of the next-nearest site at Shark Bay. The mangroves at Bunbury are even further south than this (500km). The Bunbury mangrove colonisation may have occurred relatively recently, perhaps only several thousand years ago, with propagules likely transferred by the Leeuwin Current.[7] The most inland occurrence in Australia is a growth of grey mangrove (Avicennia marina) at Mandora Marsh, some 60km from the coast.
Australian mangrove forests comprise 45 species across 18 families, which is more than half of the world's total mangrove species.[8] One species, Avicennia integra, is found only in Australia, in the Northern Territory, east of Darwin.[6]
Each mangrove species is specific to particular coordinates as well as to its own unique levels of tidal inundation.[1] The greatest diversity of species is found on the far northern and north-eastern coasts of Australia, becoming sparser with increasing latitude.[9] For example, Darwin Harbour, in the north of Australia, contains 36 mangrove tree species,[10] while Bunbury, in the south, contains only one mangrove tree species. There are no mangroves in Tasmania.[10]
The most widespread and common mangrove tree in Australia is the grey mangrove or white mangrove (Avicennia marina).[1]
Mangrove forests also support several salt-tolerant plant species which are not classed as mangroves. In tropical areas, this may include the mangrove palm (Nypa fruticans), the mangrove fern (Acrostichum speciosum), and orchids which grow as epiphytes on the trunks and branches of mangrove trees.[1] Other plants found in association with mangroves include the mangrove lily (Crinum pedunculatum).[11]
Mangrove forests share the high intertidal zone niche with coastal or intertidal saltmarshes; plant communities dominated by salt-resistant or salt-tolerant herbs and low shrubs.[12]
Associated fauna
Mangrove forests provide breeding nurseries for a wide range of fish and crustaceans, including many species of commercial and recreational value, for example, barramundi (Lates calcarifer), mangrove jack (Lutjanus argentimaculatus), mud crabs (Scylla serrata) and banana prawn (Penaeus merguinensis).[1] The forests also provide a habitat for spat settlement and development of oyster species.[13]
Many terrestrial fauna, such as insects, reptiles, frogs, birds and mammals, use mangroves for food, shelter, breeding and feeding grounds.[10]
The rusty monitor (Varanus semiremex) shelters in the hollows of mature or dead mangrove trees in north-eastern Queensland.[1] The mangrove snake (Fordonia leucobalia) and estuarine crocodile (Crocodylus porosus) are found in mangrove forests in the north.
Mangrove forests are sometimes used as nursery areas by flying foxes in the Darwin Harbour[10] and other areas of Australia. Several species, including the little red flying fox, are dependent on mangrove pollen as food.[10]
Economic values
Mangroves protect coastal areas from erosion, storm surge, and tsunamis.[15][16] The massive root systems of mangroves are efficient at dissipating wave energy.[17] Mangroves retard the tidal movement of water, allowing sediment to be deposited as the tide comes in, and leaving all except fine particles when the tide ebbs.[18] Mangroves therefore build their own environment.[15]
The commercial and recreational fishing industries are prime beneficiaries of mangrove forests, which provide breeding and feeding grounds for fish and prawns.[1] About 75% of the fish and prawns caught for commercial and recreational purposes in Queensland spend at least part of their lifecycles in mangroves.[1]
In some coastal communities, boardwalks and bird-viewing areas in mangrove forests provide attractions for the eco-tourism industry, for example, at Boondall Wetlands.[1]
Threats
Threats to mangrove ecosystems include;
coastal modifications such as reclaiming land (e.g. for building canal estates and marinas);[19]
erosion of shorelines in coastal lakes and estuaries;[19]
elevated levels of nutrients and sediments from land clearing, overgrazing and cropping;[19]
increased levels of heavy metals such as copper, lead, cadmium, zinc and mercury, and tributyl tin (TBT) from anti-fouling paints;[19]
marine oil pollution from sewage systems and drains, which is estimated at 16,000 tonnes a year over the whole of Australia;[19]
accidental spills during re-fuelling of vessels in ports.[19]
Removal of mangrove forests can lead to erosion of the shoreline, exposure of acid sulphate soils, shallowing of estuaries and waterways, and a reduction in water quality.[10][20]
These threats can deplete the populations of fish, prawns, crabs and other sea life that use mangroves as breeding and feeding grounds, which would then impact on commercial and recreational fishing.[19]
Protection and preservation
About one-third of the total area of Australian mangrove forest is privately-owned, including indigenous reserves,[1] with around 18% of the total mangrove areas located within national parks or other officially protected areas.[1]
Mangroves are protected in Queensland under the Fisheries Act 1994, and in Western Australia under the Wildlife Conservation Act 1950.
As the benefits of mangroves become more widely known and valued, grassroots efforts to protect them are becoming more frequent. Boardwalks provide visual opportunities for visitors to experience the habitat, further educating the public on the ecological, economic and environmental necessities of mangroves.[1]
The Royal National Park is a protected national park that is located in Sutherland Shire local government area in the southern portion of Sydney, New South Wales, Australia.
Sundarbans is a mangrove area in the delta formed by the confluence of the Ganges, Brahmaputra and Meghna Rivers in the Bay of Bengal. Sundarban Reserve Forest (SRF) of Bangladesh is the largest mangrove forest in the world. It spans the area from the Baleswar River in Bangladesh's division of Khulna to the Hooghly River in India's state of West Bengal. It comprises closed and open mangrove forests, land used for agricultural purpose, mudflats and barren land, and is intersected by multiple tidal streams and channels. Sundarbans is home to the world's largest area of mangrove forests. Four protected areas in the Sundarbans are enlisted as UNESCO World Heritage Sites, viz. Sundarbans West (Bangladesh), Sundarbans South (Bangladesh), Sundarbans East (Bangladesh) and Sundarbans National Park (India).
The Towra Point Nature Reserve is a protected nature reserve that is located in Sutherland Shire, Southern Sydney, New South Wales, in eastern Australia. The 603-hectare (1,490-acre) reserve is situated on the southern shores of Botany Bay at Kurnell, within the Sutherland Shire. The reserve is protected under the Ramsar Convention as a wetland of international importance as an important breeding ground for many vulnerable, protected, or endangered species. The Towra Point Aquatic Nature Reserve is located in the surrounding waterways.
Avicennia marina, commonly known as grey mangrove or white mangrove, is a species of mangrove tree classified in the plant family Acanthaceae. As with other mangroves, it occurs in the intertidal zones of estuarine areas.
Coringa Wildlife Sanctuary is an estuary situated near Kakinada in Andhra Pradesh, India. It is the third largest stretch of mangrove forests in India with 24 mangrove tree species and more than 120 bird species. It is home to the critically endangered white-backed vulture and the long billed vulture. Mangroves are a group of trees and shrubs that live in the coastal intertidal zone, with a dense tangle of prop roots that make the trees appear to be standing on stilts above the water. This tangle of roots allows the trees to handle the daily rise and fall of tides; hence, the mangrove forest gets flooded at least twice per day. The roots also slow the movement of tidal waters, causing sediments to settle out of the water and build up the muddy bottom.
The Australian rufous fantail is a small passerine bird, most commonly known also as the black-breasted rufous-fantail or rufous-fronted fantail, which can be found in Australia.
The Shoalwater Bay Military Training Area is a heritage-listed military installation at Byfield Road, Byfield, Shire of Livingstone, Queensland, Australia. It is a large, relatively undisturbed and intact natural system with a wide variety of coastal landforms and a high level of biodiversity. It contains a diverse range of marine and coastal wetland landscapes, vegetation types and ecosystems. It was added to the Australian Commonwealth Heritage List on 22 June 2004.
The leaden flycatcher is a species of passerine bird in the family Monarchidae. Around 15 cm (6 in) in length, the male is lustrous azure with white underparts, while the female possesses leaden head, mantle and back and rufous throat and breast. It is found in eastern and northern Australia, Indonesia, and Papua New Guinea. Its natural habitat is subtropical or tropical mangrove forests in the northern parts of its range, in the south and inland it is eucalypt woodland.
The red-headed myzomela or red-headed honeyeater is a passerine bird of the honeyeater family Meliphagidae found in Australia, Indonesia, and Papua New Guinea. It was described by John Gould in 1840. Two subspecies are recognised, with the nominate race M. e. erythrocephala distributed around the tropical coastline of Australia, and M. e. infuscata in New Guinea. Though widely distributed, the species is not abundant within this range. While the IUCN lists the Australian population of M. e. infuscata as being near threatened, as a whole the widespread range means that its conservation is of least concern.
The New Guinea mangroves is a mangrove ecoregion that covers extensive areas of the coastline New Guinea, the large island in the western Pacific Ocean north of Australia.
Mangrove ecosystems represent natural capital capable of producing a wide range of goods and services for coastal environments and communities and society as a whole. Some of these outputs, such as timber, are freely exchanged in formal markets. Value is determined in these markets through exchange and quantified in terms of price. Mangroves are important for aquatic life and home for many species of fish.
Hungry Bay Nature Reserve is a nature reserve on the east coast of Bermuda. It was established in 1986. It is considered the best example of coastal mangrove swamp on the island. It includes the Hungry Bay area and the largest mangrove coastal swamp in Bermuda. It is protected by a Tree preservation order (T.P.O.) and designated as an official Nature Reserve within the Parks system of Bermuda.
Pulo Island, commonly known as Isla Pulo, is a long, narrow island surrounded by mudflats in the Manila Bay coast of Navotas, about 13 kilometers (8.1 mi) north of Manila in the Philippines. It is a sitio in Barangay Tanza, connected to the mainland of Navotas by a 500-meter-long (1,600 ft) bamboo bridge. The island is known for its mangroves for which it was declared a "marine tree park" and as one of four ecotourism sites in Metro Manila established under the National Ecotourism Strategy in 1999. In 2014, it was home to a resettlement site of about 137 indigent families that mostly occupied the island's southern tip.
The Red River Delta Biosphere Reserve is a UNESCO biosphere reserve in the coastal region of northern Vietnam. Mangroves and intertidal habitats of the Red River Delta form wetlands of high biodiversity especially in the Xuan Thuy and Tien Hai districts. These wetlands are of global importance as migratory sites for several bird species.
The Gulf of Panama mangroves (NT1414) is an ecoregion along the Pacific coast of Panama and Colombia. The mangroves experience seasonal flooding with high levels of sediment, and occasional extreme storms or very low rainfall due to El Niño effects. They are important as a breeding or nursery area for marine species. Areas of the mangroves have been recognized as Important Bird Areas and Ramsar wetlands. The ecoregion has been severely degraded by clearance of mangroves for agriculture, pasturage and shrimp farming, by urban pressure around Panama City, and by pollution related to the Panama Canal.
Wide Bay Military Reserve is a heritage-listed military installation at Tin Can Bay Road, Tin Can Bay, Queensland, Australia. The reserve supports a diverse range of plant communities from estuarine, strand, wetlands, heath, tall shrublands and woodlands, to the open forests of the sub-coastal hills and ranges. The total number of bird species recorded for the place totals 250, which is high by Australian standards. It was added to the Australian Commonwealth Heritage List on 22 June 2004.
Qurm Nature Reserve is a national nature reserve in Muscat Governorate, Oman. Located on the Gulf of Oman coast, the reserve protects a mangrove forest and the surrounding wetland in a small estuary within the urban area of Qurm. Established in 1975, the reserve has been designated as an Important Bird Area since 1994, and as a protected Ramsar site since 2013.
1 2 Duke, Norman (2006). Australia's Mangroves. Brisbane: University of Queensland & Norman C Duke. ISBN0-646-46196-6.
↑ Rippey, Elizabeth; Rowland, Barbara (2004) [1995]. Coastal plants: Perth and the south-west region (2nded.). Perth: UWA Press. ISBN978-1-920694-05-0.
1 2 Simpson, Ken; Day, Nicolas; Trusler, Peter (2004). Field Guide to the Birds of Australia 7th Edition. Penguin Group (Australia). ISBN978-0-670-04180-0.
1 2 Mazda, Y.; Kobashi, D. and Okada, S. (2005) "Tidal-Scale Hydrodynamics within Mangrove Swamps" Wetlands Ecology and Management 13(6): pp. 647–655
↑ Danielsen, F. et al. (2005) "The Asian tsunami: a protective role for coastal vegetation" Science 310: p. 643.
↑ Massel, S. R.; Furukawa, K.and Brinkman R. M. (1999) "Surface wave propagation in mangrove forests" Fluid Dynamics Research 24(4): pp. 219–249
↑ Mazda, Yoshihiro et al. (1997) "Drag force due to vegetation in mangrove swamps" Mangroves and Salt Marshes 1: pp. 193–199
1 2 3 4 5 6 7 Zann, Leon P. (1995) [1995]. "Marine Pollution". Our Sea, Our Future – Major findings of the State of the Marine Environment Report for Australia. Australian Government, Dept of Environment, Water, Heritage, and the Arts. ISBN978-0-642-17391-1. ISBN. Retrieved 23 January 2011.
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