Duke and Wolanski, 2001: 

Loss of catchment vegetation - more mud in estuarine waters

"Over the last 100 to 200 years, the catchment areas of all coastal river systems in the GBR have been impacted by land use change involving the conversion of natural habitat to grazing lands, agricultural cultivation, and mining, as well as urban and indistrial development areas. These often dramatic alterations in land use have resulted in the severe loss of natural vegetation, and rapid increase in erosion of catchment sediments."

"One indication of current catchment condition is provided by the amount of remaining natural vegetation. In Table 1, seven catchment systems are shown from Trinity Inlet, around Cairns, to the Morton Region, around Brisbane. The percentage of remaining natural vegetation ranged from 14.9% in the Port Curtis region, to greater than 90% in the Hinchinbrook area."

Mud accumulation and new mangroves in downstream parts of estuaries and nearshore areas.

"Sediment washed down from the catchments has accumulated in estuaries and along nearshore coastlines. Direct evidence of these sediments is notable today as mud along foreshore areas, as well as the often enlarged new areas of downstream estuarine mangroves. Examples of this can be seen in many areas including Trinity Inlet and Pioneer River estuaries."

"The areas of new mangroves therefore could be used as an indirect measure of trends in fine sediment accumulation, and related to soil loss as measure of catchment degradation. In this way, the estimates of percent new mangroves presented in Table 1, provide a means to rank catchment degradation. This parameter integrates a complex mix of influencing factors, including the extent of cleared land  as well as differences in land use combined with climatic variables, particularly rainfall volume and periodicity. In this latter sense, catchments in higher rainfall areas would be expected to be more vulnerable to land use change. This may explain why Moresby and Johnstone River catchments appear most affected by degradation of their respective catchment areas." 

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Citation and/or URL

Duke, N.C. and Wolanski, E., 2001, Muddy coastal waters and depleted mangrove coastlines - depleted seagrass and coral reefs, In, Oceanographic processes of coral reefs: physical and biological links in the Great Barrier Reef, ed. Wolanski E., CRC Press, 77-88.

Spatial Coverage

Six catchments in the GBR region and one south of the GBR 

Temporal Coverage

1950s to 1990s 

Update Frequency

 Not applicable 

Other Information

 None