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Factors affecting the decline of a freshwater mussel and its host fish in Western Australia

Lymbery, A.J., Klunzinger, M.W., Morgan, D.L. and Beatty, S.J. (2010) Factors affecting the decline of a freshwater mussel and its host fish in Western Australia. In: 12th International Congress of Parasitology, 15-20 August 2010, Melbourne, Vic..

Abstract

The south west of Western Australia has a unique and threatened freshwater fish fauna. A recent survey of the parasites of freshwater fishes in the region suggested that the possible extinction of endemic freshwater fish species also threatened a unique parasite fauna. In this study we examine the distribution, host preference and environmental factors influencing the demography of the freshwater mussel, Westralunio carteri (Unionoida: Hyriidae). Westralunio carteri, the only representative of the genus found in Australia, is restricted to the Southwest Coast Drainage Division, and a comparison of current distribution with historical museum records indicates a severe range contraction over the last 50 years. In addition, the size distribution of many extant populations of this long-lived mussel suggests that recruitment is limited, and that the species will soon be facing a major extinction debt. Unusually for unionoid mussels in Australia, W. carteri is highly host specific, with the parasitic glochidial stage found almost entirely on the freshwater catfish, Tandanus bostocki. The development and release of glochidia by W. carteri occurs at the time of pre-spawning dispersal by T. bostocki and there is evidence that glochidial release attracts feeding catfish. Furthermore, free-living stages of mussels represent a major food item in the diet of catfish. Laboratory experiments have found a low salt-tolerance for both W. carteri and T. bostocki and we suggest that the increasing salinisation of Western Australian rivers is the principal driver of changes in the joint distributions of these two species.

Publication Type: Conference Item
Murdoch Affiliation: Centre for Fish and Fisheries Research
Publisher: World Federation of Parasitologists
URI: http://researchrepository.murdoch.edu.au/id/eprint/5428
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