Muddy coastal waters and depleted mangrove coastlines - depleted seagrass and coral reefs

Duke, Norman, and Wolanski, Eric (2001) Muddy coastal waters and depleted mangrove coastlines - depleted seagrass and coral reefs. In: Wolanski, Eric, (ed.) Oceanographic Processes of Coral Reefs: physical and biology links in the Great Barrier Reef. CRC Press, Washington, DC, USA, pp. 77-91.

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Along the tropical north-eastern coast of Queensland is one of the outstanding biotic ecosystems in the world, the Great Barrier Reef (GBR), attested to be the only biotic structure in the world visible from space. This complex series of reef communities is based on tiny coral polyps and deep accumulations of their carbonate skeletons over eons. The resulting barrier to ocean waves has created a vast and relatively sheltered coastal lagoon in which other complex biotic tropical ecosystems have flourished in association with coral reefs. Two chief types of ecosystems dominate these sheltered waters, namely, the mostly subtidal seagrass meadows in the extensive coastal lagoon, and mangrove and salt marsh growing along the upper intertidal zone and within all estuaries. These ecosystems are highly dependent not only on each other, but also on prevailing environmental conditions in a dynamic equilibrium. It is of fundamental importance also that each of these biotic communities is based on plants for the provision of both their physical living structure as well as via complex trophic food webs which support a myriad of associated organisms. In this way, mangrove, salt marsh, seagrass and reef-building corals provide primary production by photosynthesis and fixation of atmospheric carbon – a function and role which extends well beyond their mere presence and benefit as habitat. Accumulation of carbon is particularly important for the structure created not only by reef building corals of the GBR, but also within the extensive mangrove forests (Duke, 1997; Alongi, 1998; Alongi et al., 1998). Like coral reefs, mangrove forests provide essential shelter and protection for coastal shorelines in north-eastern Queensland. Where corals provide the first line of protection in offshore clearer waters, mangroves provide a second level of protection along nearshore areas where water clarity is often muddy and, sediments and substrate are typically soft. Such conditions are typically unsuitable for corals. These ecosystems are therefore seen as mutual and symbiotic since each ecosystem cannot prevail or dominate where the conditions might be reversed. The advantage in the relationship for mangroves is based primarily on shelter from strong wave action provided by the coral reef barrier, allowing mangroves to have colonised and stabilised the estuarine soft sediments deposited in river mouths. By contrast, the advantage for corals is based on consistently high levels of water clarity primarily, and secondarily on the regular supply of nutrients from terrestrial runoff. Mangroves essentially support these conditions by acting as filters to trap fine sediments and improve water clarity, by binding and holding sediments with their specialised root structures. In this way, nutrients from the land may disperse offshore in relatively clearer waters suitable for coral reef development (see the chapter by Fabricius and De'ath in this book).

Item ID: 48919
Item Type: Book Chapter (Research - B1)
ISBN: 978-0-8493-0833-8
Keywords: mangrove; habitat; loss; new; sediments; deposition; catchment; vegetation; GBR; Great Barrier Reef; Queensland; Australia; IWP
Date Deposited: 20 Jul 2017 23:16
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 30%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 40%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 30%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 40%
96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960609 Sustainability Indicators @ 30%
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