Connectivity, habitat, and flow regime influence fish assemblage structure: Implications for environmental water management in a perennial river of the wet-dry tropics of northern Australia
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Author(s)
Pusey, Bradley J
Douglas, Michael
Olden, Julian D
Jackson, Sue
Allsop, Quentin
Kennard, Mark J
Year published
2020
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Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd Environmental water management seeks to balance competing demands between the water needed to sustain human populations and their economic activities and that required to sustain functioning freshwater ecosystems and the species they support. It must be predicated on an understanding of the environmental, hydrological, and biological factors that determine the distribution and abundance of aquatic species. The Daly River of the wet–dry tropics of northern Australia consists of a perennially flowing main stem and large tributaries, as ...
View more >Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd Environmental water management seeks to balance competing demands between the water needed to sustain human populations and their economic activities and that required to sustain functioning freshwater ecosystems and the species they support. It must be predicated on an understanding of the environmental, hydrological, and biological factors that determine the distribution and abundance of aquatic species. The Daly River of the wet–dry tropics of northern Australia consists of a perennially flowing main stem and large tributaries, as well as many small to large naturally intermittent tributaries, and associated off-channel wetlands. Increased groundwater abstraction to support irrigated agriculture during the dry season threatens to reduce dry-season flows that maintain perenniality and persistence of freshwater fishes. Fish assemblages were surveyed at 55 locations during the dry season over a 2-year period with the goal of establishing the key landscape-scale and local-scale (i.e. habitat) drivers of fish species distribution. Longitudinal (upstream/downstream) and lateral (river/floodplain) gradients in assemblage structure were observed with the latter dependent on the position in the river landscape. Underlying these gradients, stream flow intermittency influenced assemblage composition, species richness, and body size distributions. Natural constraints to dispersal were identified and their influence on assemblage structure was also dependent on position within the catchment. Eight distinct assemblage types were identified, defined by differences in the abundance of species within five groups differing in functional traits describing body size, spawning requirements, and dispersal capacity. These functional groups largely comprised species widely distributed in northern Australia. The results of the study are discussed with reference to the environmental flow needs of the Daly River and other rivers of northern Australia. The findings may also be applied to environmental flow management in savannah rivers elsewhere.
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View more >Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd Environmental water management seeks to balance competing demands between the water needed to sustain human populations and their economic activities and that required to sustain functioning freshwater ecosystems and the species they support. It must be predicated on an understanding of the environmental, hydrological, and biological factors that determine the distribution and abundance of aquatic species. The Daly River of the wet–dry tropics of northern Australia consists of a perennially flowing main stem and large tributaries, as well as many small to large naturally intermittent tributaries, and associated off-channel wetlands. Increased groundwater abstraction to support irrigated agriculture during the dry season threatens to reduce dry-season flows that maintain perenniality and persistence of freshwater fishes. Fish assemblages were surveyed at 55 locations during the dry season over a 2-year period with the goal of establishing the key landscape-scale and local-scale (i.e. habitat) drivers of fish species distribution. Longitudinal (upstream/downstream) and lateral (river/floodplain) gradients in assemblage structure were observed with the latter dependent on the position in the river landscape. Underlying these gradients, stream flow intermittency influenced assemblage composition, species richness, and body size distributions. Natural constraints to dispersal were identified and their influence on assemblage structure was also dependent on position within the catchment. Eight distinct assemblage types were identified, defined by differences in the abundance of species within five groups differing in functional traits describing body size, spawning requirements, and dispersal capacity. These functional groups largely comprised species widely distributed in northern Australia. The results of the study are discussed with reference to the environmental flow needs of the Daly River and other rivers of northern Australia. The findings may also be applied to environmental flow management in savannah rivers elsewhere.
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Journal Title
Aquatic Conservation: Marine and Freshwater Ecosystems
Volume
30
Issue
7
Copyright Statement
© 2020 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Subject
Environmental sciences
Biological sciences
Agricultural, veterinary and food sciences
Science & Technology
Life Sciences & Biomedicine
Physical Sciences
Marine & Freshwater Biology