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Groundwater dependent fish communities in the Blackwood River: understanding migration patterns and the influence of salinisation and river connectivity

Beatty, S., McAleer, F. and Morgan, D. (2008) Groundwater dependent fish communities in the Blackwood River: understanding migration patterns and the influence of salinisation and river connectivity. In: 47th Australian Society for Limnology Congress, 30 Sept. - 2 Oct. 2008, Mandurah, Western Australia .

Abstract

Groundwater reserves form an important component of drinking water supply options in Western Australia; however, an understanding of their importance in maintaining ecologically significant aquatic communities prior to their exploitation is required to ensure those ecological values are maintained. This ongoing study began in 2005 and is examining the fish migration patterns, population demographics and community structure in the Blackwood River and its tributaries within and outside the surface expression zone of a major south-west aquifer, the Yarragadee. These patterns are being related to environmental variables and the reliance of these communities on groundwater discharge is being assessed. Many of the spatial and temporal variations in migration patterns are attributed to differences in hydrological regimes of these systems. Groundwater input into the Blackwood is proportionally most significant in summer and autumn and this creates refuge habitats for these endemic species. Sites receiving most groundwater discharge having considerably greater abundances of salt-intolerant freshwater endemic species than those upstream of the discharge. Freshwater Cobbler was identified as a key indicator species in the main channel with its baseflow migration strength being positively related to level of discharge. The key indicator species in the groundwater dependant tributaries within the expression zone is the (EPBC listed) threatened Balston’s Pygmy Perch as it only breeds in the perennial Milyeannup Brook resulting in it being particularly vulnerable to groundwater reduction. Considerable interannual variations existed in the migration patterns that highlight the importance of designing and undertaking ecological assessments that are able to quantify this variability.

Publication Type: Conference Item
Murdoch Affiliation: Centre for Fish and Fisheries Research
Notes: Oral presentation
URI: http://researchrepository.murdoch.edu.au/id/eprint/6005
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