Abstract
Setting ecologically based water-extraction rules requires an understanding of the relationships between hydrology and the completion of aquatic organism life cycles. Successful reproduction of riverine fishes has been linked to hydrological variation across diverse climatic regions. However, the reproductive ecology for many species in wet–dry tropical northern Australia is poorly understood, and consequently there is little knowledge on how temporal (seasonal) and spatial hydrological variation influences fish reproduction in this region. This study aimed to quantify the hydrology-related reproductive ecologies of freshwater fish across the wet–dry seasonal cycle and between differing hydrological classes in a northern Australian river (Daly River, Northern Territory) subject to increasing interest in water extraction. Sampling of larval and juvenile fish was undertaken over 1 year at eight sites classified into perennial and intermittent flow types. Fish spawning phenologies were developed and spatial–temporal dynamics in larval fish assemblages were investigated using model-based multivariate and univariate analyses. Spawning occurred in all hydrological seasons, with low-flow dry season periods identified as important for many fish taxa. For a different fish assemblage, spawning mostly occurred during high-flow wet season periods. Larval assemblages in the wet season were more diverse than in the dry and wet–dry seasons. Perennial sites maintained higher diversity than intermittent sites year-round; however, larvae were more abundant in intermittent sites for some taxa. Spatial and temporal differences in larval assemblages were largely explained by variation in the occurrence and relative abundance of three aseasonally spawning taxa (Craterocephalus spp., Melanotaenia spp. and Ambassis spp.) and the largely wet-period spawning of Terapontidae spp. These results add to growing evidence of variation in spawning phenologies among fish species and the use of multiple hydrological phases for aseasonal reproduction. The diverse range of hydrological conditions used for spawning and rearing, and the differences between hydrological river classes among taxa, suggests that water-extraction and environmental flow rules should aim to maintain hydrological conditions catchment-wide during both low and high-flow periods to reduce the risk of impacting fish reproduction. In particular, the results suggest that if perennially flowing sites began to flow intermittently, such as through over-extraction of water or due to climate change, less diverse fish assemblages may result. This study expands our understanding of the relationships between hydrology and the reproductive ecology of freshwater fish in wet–dry tropical climates and may inform future ecologically based approaches to setting water-extraction rules.
Original language | English |
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Pages (from-to) | 1949-1967 |
Number of pages | 19 |
Journal | Freshwater Biology |
Volume | 66 |
Issue number | 10 |
Early online date | Jul 2021 |
DOIs | |
Publication status | Published - Oct 2021 |
Bibliographical note
Funding Information:We gratefully acknowledge the Wagiman, Wardaman, Jawoyn and Malak Malak people ‐ the traditional indigenous owners of the parts of the Daly River system that the study took place. We also want to highlight the ongoing partnership with Tjuwaliyn Wagiman Aboriginal Corporation (TWAC) and their contribution through a research agreement, field support and for their indigenous ecological knowledge, managing country and their spiritual connection to lands and waters, as fishing is an integral component of their connection on Wagiman traditional land and waters, and for their to ensure safe travels for researchers on Wagiman land and waters. We wish to thank B. J. Adair for fieldwork assistance, and G. Saboret, B. H. Roberts, K. Keller, and L. S. Stapp for assistance in the lab. K. J. T wishes to thank M. Kaestli and D. I. Warton for their assistance in identifying and optimising statistical analyses. Funding for this project was provided by an Australian Research Council (ARC) Linkage Project (LP150100388) and through the National Environmental Science Program (NESP) ‐ Northern Australia Environmental Resources Hub project (Project 1.3.2). K. J. T. was supported by the Australian Government Research Training Program Scholarship and ARC and NESP top‐up scholarships. All procedures were conducted under protocols approved by the Charles Darwin University Animal Ethics Committee (Permit Approval number A16022). Field work was performed under Northern Territory Fisheries Special Permit No. 2016‐2017/S17/3403. water blessing ceremony
Publisher Copyright:
© 2021 The Authors. Freshwater Biology published by John Wiley & Sons Ltd.
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.