Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/14573
Title: Fish recruitment in rivers with modified discharge depends on the interacting effects of flow and thermal regimes
Contributor(s): Rolls, Robert J (author); Growns, Ivor  (author); Khan, Tariq A (author); Wilson, Glenn  (author); Ellison, Tanya (author); Prior, Andrea (author); Waring, Caroline C (author)
Publication Date: 2013
DOI: 10.1111/fwb.12169
Handle Link: https://hdl.handle.net/1959.11/14573
Abstract: Summary 1. Alteration of flow and thermal regimes is a key consequence of human use of river and floodplain ecosystems, and these impacts result from a range of interacting ecological mechanisms. Environmental flow regimes are a management strategy to restore or maintain ecologically important aspects of river hydrology. However, inadequate understanding of the processes that determine the effects of flow on population dynamics of biota hinders the maximum benefits of environmental flows. 2. Spawning and recruitment of riverine fish is mediated by temperature, access to nursery habitat and the timing and availability of resources. Differences in population sizes between regulated and unregulated rivers are often attributed to the effect of flow and thermal regime change on population dynamics. 3. Dams and extraction of water have altered the flow and thermal regimes of rivers in the northern Murray–Darling Basin, Australia. Combining three studies, we (i) examined differences in the recruitment of fish and patterns of potential prey availability between a regulated and unregulated river, (ii) studied the relationships between patterns of flow and temperature on spawning of fish in two rivers with contrasting regulated flow regimes and (iii) experimentally tested the effects of environmental flow releases in a regulated river on fish spawning and recruitment by comparing patterns over time against two unregulated rivers. 4. Comparisons between regulated and unregulated rivers indicated that the significantly lower recruitment of 'Macquaria ambigua' in the regulated river was linked with large differences in available prey. Species-specific differences in the abundance of fish larvae between two regulated rivers indicated that different reproductive strategies determine population-level responses to flow regulation. Finally, the experimental flow releases in a regulated reach during late spring did not result in a change in spawning and recruitment of fish, although influences of antecedent flow and temperature on larval and juvenile assemblage composition were significant. 5. These findings indicate that the responses of fish spawning and recruitment to flow regime change and restoration are dependent on the conditions that determine the success of these critical life-history processes. Specifically, key effects of flow regulation are reduced summer water temperatures due to hypolimnetic discharge from dams, and the reduced frequency and duration of low flows. Reduced water temperatures limit opportunities for fish to spawn, and sustained base flows were associated with lower densities of potential prey sources in conjunction with potential flushing of larvae and juveniles, thereby influencing recruitment. 6. The benefits of environmental flow programmes can be enhanced if flow regimes are modified to ensure that abiotic and biotic conditions that support persistence of biota are provided. In conjunction with flow pulses and floods, low flows are a natural and ecologically important component of flow regimes, particularly in dryland rivers. Understanding the interactive and mechanistic effects of flow and thermal regimes on population viability and patterns of biodiversity is critical to maximising the value of environmental flows.
Publication Type: Journal Article
Source of Publication: Freshwater Biology, 58(9), p. 1804-1819
Publisher: Wiley-Blackwell Publishing Ltd
Place of Publication: United Kingdom
ISSN: 1365-2427
0046-5070
Fields of Research (FoR) 2008: 050202 Conservation and Biodiversity
050204 Environmental Impact Assessment
050102 Ecosystem Function
Fields of Research (FoR) 2020: 410401 Conservation and biodiversity
410402 Environmental assessment and monitoring
410203 Ecosystem function
Socio-Economic Objective (SEO) 2008: 960807 Fresh, Ground and Surface Water Flora, Fauna and Biodiversity
960913 Water Allocation and Quantification
960506 Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments
Socio-Economic Objective (SEO) 2020: 180303 Fresh, ground and surface water biodiversity
180502 Assessment and management of pelagic marine ecosystems
190211 Water policy (incl. water allocation)
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Appears in Collections:Journal Article

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