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Groundwater intrusion maintains endemic freshwater fishes in South-Western Australia

Beatty, S. and Morgan, D. (2011) Groundwater intrusion maintains endemic freshwater fishes in South-Western Australia. In: 13th International River Symposium, 11 - 14 October, Perth, Western Australia.

Abstract

The freshwater fishes of the Southwest Coast Drainage Division of Australia are depauperate yet highly endemic. These fauna continue to be severely impacted by habitat alterations that have led to considerable population declines. In particular, secondary salinisation has recently been identified as a major cause of these range reductions of these species. Despite these declines, the role that fresh groundwater intrusions have on maintaining critical refuge habitats is poorly understood. Using two case studies from the Swan-Canning catchment and the Blackwood River, this presentation discusses how salinisation has led to range contractions of the freshwater fish fauna and concomitant inland expansions of estuarine species. It then presents findings from the long-term (five year) study into the relationships between freshwater fish movement patterns, habitat usage and prevailing environmental variables in the Blackwood River (the largest by discharge in the region). The study reveals clear relationships between surface and groundwater flow and ecology of freshwater fishes in this system and demonstrates that fresh groundwater intrusion plays a crucial role in maintaining threatened freshwater fish populations. Management implications are outlined in terms of setting ecologically sustainable levels of groundwater extractions from the south-west in light of continuing rainfall reductions due to climate change.

Publication Type: Conference Item
Murdoch Affiliation: Centre for Fish and Fisheries Research
URI: http://researchrepository.murdoch.edu.au/id/eprint/7866
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