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The aquatic fauna of King Island's streams and wetlands

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Davies, PE and Brown, K and Sloane, T and Walker, Rodney and Cook, LSJ (2002) The aquatic fauna of King Island's streams and wetlands. Project Report. Freshwater Systems, Hobart.

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Abstract

King Island has a wide range of freshwater aquatic environments including rivers and streams and ephemeral and permanent wetlands (ponds, swamps, lagoons). The fauna of these environments is not well known, and the writing of this chapter required some new sampling to be done. As a result we now know that the island has many species (more than 140) of aquatic macroinvertebrates, including burrowing crayfish, aquatic insects, freshwater crabs and snails, as well as eight species of freshwater fish. The island is highly seasonal in its rainfall, and, as a consequence most of the streams and rivers have very low or no flow during the summer and autumn months. Some sections have permanent water, especially near the coast or those associated with springs or escarpments. The landscape of the island has changed substantially since European settlement, and significant changes have occurred to its freshwater habitats. Most of the catchments no longer have their original vegetation cover, and that, coupled with intensive agriculture, has undoubtedly led to changes in stream flows and water quality. Changes to the bankside or riparian vegetation have been significant, with many stream sections and wetlands now having no or limited areas of natural riparian vegetation (1), and with many of these areas being accessed by stock, with effects on bank erosion and water quality. There is evidence of higher levels of turbidity, nutrients and salinity in several streams, as well as in some wetlands (2, K Brown unpub data). Before European settlement, most of the streams on the island were swamp-channel complexes with shallow channels containing large amounts of woody and other organic matter, often overlying sands. They were heavily shaded, slow flowing (except for in the south east) and many sections probably experienced seasonal (summer) drops in dissolved oxygen levels due to decomposition of organic material, during periods of slow flow and higher temperatures. In some cases, surface waters in swamps and lagoons and some stream sections were probably devoid of oxygen and contained hydrogen sulphide (rotten egg gas). This can be seen today in places like Collier's Swamp. Overall though, water quality was probably better than today, and stream habitats were more uniform across the island. Despite these changes and the highly seasonal rainfall, the majority of streams and wetlands on the island still manage to maintain a reasonably diverse fauna, which in many cases is highly abundant.

Item Type: Report (Project Report)
Keywords: Aquatic fauna, stream, King Island, freshwater
Publisher: Freshwater Systems
Date Deposited: 24 Nov 2006
Last Modified: 18 Nov 2014 03:12
URI: http://eprints.utas.edu.au/id/eprint/429
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