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Factors influencing the characteristics of the fish faunas in offshore, deeper waters of permanently-open, seasonally-open and normally-closed estuaries
Citation
Chuwen, BM and Hoeksema, SD and Potter, IC, Factors influencing the characteristics of the fish faunas in offshore, deeper waters of permanently-open, seasonally-open and normally-closed estuaries, Estuarine, Coastal and Shelf Science, 81, (2009) pp. 279-295. ISSN 0272-7714 (2009) [Refereed Article]
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Copyright Statement
Copyright © 2008 Elsevier Ltd The definitive version is available at http://www.sciencedirect.com
DOI: doi:10.1016/j.ecss.2008.11.001
Abstract
This study explored the ways in which various factors influence the species compositions, species
richness and catch rates of fishes in offshore, deeper waters of the basin and river regions of five
estuaries, which are located along ca 400 km of the southern coastline of Western Australia and differ
markedly in their physico-chemical characteristics. Gill netting seasonally for two years at sites in the
basin and saline lower reaches of the main tributary of the seasonally-open Broke, Irwin and Wilson
inlets, the permanently-open Oyster Harbour and the normally-closed Wellstead Estuary yielded 22,329
fishes representing 58 species. Overall, and irrespective of estuary type, the species compositions of the
basins and rivers differed markedly. This was attributable to consistently greater abundances of Mugil
cephalus, and usually also of Acanthopagrus butcheri, in the rivers of each estuary and to the restriction of
a range of species largely to the basins. However, the compositions in the basins of the five estuaries
varied markedly, reflecting differences in the extent and duration of the opening of the estuary mouth
and/or whether extensive growths of macrophytes were present. Changes in the ichthyofaunal
composition of the normally-closed Wellstead Estuary between the first and second years of the study
were attributable, in particular, to the movement of two mugilid species into offshore waters as they
increased in size. Cyclical changes in ichthyofaunal composition were conspicuous in both regions of the
estuary that underwent the most pronounced seasonal variations in environmental conditions. In each
estuary, species richness was greater in the basin than river, where salinities were more variable and fell
to lower levels and were thus less conducive to the immigration of most marine species. Catch rates were
least in Broke Inlet, which had the lowest primary productivity, and were particularly high in Wellstead
Estuary, which is highly eutrophic. The results of this study emphasise that ichthyofaunal composition
can vary greatly with region (basin vs river) in microtidal estuaries, a finding that is of direct relevance to
managers as these systems are becoming increasingly degraded and yet still constitute important
nursery areas for certain fish species and often support recreational and commercial fisheries.
Item Details
Item Type: | Refereed Article |
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Keywords: | microtidal estuaries, estuary mouth closure, environmental variability, ichthyofaunal characteristics, region of estuary life-cycle guilds, Western Australia, south coast, 116.36119.42E, 34.4135.04S |
Research Division: | Agricultural, Veterinary and Food Sciences |
Research Group: | Fisheries sciences |
Research Field: | Aquaculture |
Objective Division: | Animal Production and Animal Primary Products |
Objective Group: | Fisheries - wild caught |
Objective Field: | Fisheries - recreational freshwater |
UTAS Author: | Chuwen, BM (Dr Ben Chuwen) |
ID Code: | 71846 |
Year Published: | 2009 |
Web of Science® Times Cited: | 21 |
Deposited By: | Sustainable Marine Research Collaboration |
Deposited On: | 2011-08-10 |
Last Modified: | 2013-01-09 |
Downloads: | 1 View Download Statistics |
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