A Large-scale, Hierarchical Approach for Assessing Habitat Associations of Fish Assemblages in Large Dryland Rivers |
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Authors: | Craig A Boys Martin C Thoms |
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Institution: | (1) Water Research Centre, Cooperative Research Centre for Freshwater, University of Canberra, 2601, ACT, Australia;(2) NSW Department of Primary Industries, Port Stephens Fisheries Centre, Taylors Beach Road, 2316 Taylors Beach, NSW, Australia |
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Abstract: | Multiple-scale assessments of fish-habitat associations are limited despite the fact that riverine fish assemblages are influenced
by factors operating over a range of spatial scales. A method for assessing fish-habitat assemblages at multiple scales is
proposed and tested in a large Australian dryland river, the Barwon–Darling River. Six discrete mesohabitat types (large wood,
smooth bank, irregular bank, matted bank, mid-channel and deep pool) nested within 10 km long river reaches were sampled.
Individual reaches were, in turn, nested within four larger geomorphological zones, previously identified along the river.
Fish assemblages varied significantly between mesohabitat types and at different spatial scales. Golden perch (Macquaria ambigua), Murray cod (Maccullochella peelii peelii) and common carp (Cyprinus carpio) were strongly associated with large wood, but golden perch and Murray cod exhibited higher habitat specificity than carp.
Bony herring (Nematalosa erebi) were more common in shallow edgewater habitats. At the river-scale, regional differences in the fish assemblage occurred
at scales closely corresponding to geomorphological zones and these differences were associated with changes in the relative
abundance of species rather than the addition or replacement of species. The proposed hierarchical framework improves the
efficiency of fish surveys in large rivers by viewing meso-scale fish-habitat associations in the context of larger-scale
geomorphological processes. |
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Keywords: | fish-habitat associations functional process zones hierarchy theory spatial scaling Murray– Darling Basin |
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