Population structure and microhabitat preference of a threatened freshwater mussel, Westralunio carteri, in south-western Australia

Abstract Freshwater mussels are important functional components of aquatic ecosystems. Westralunio carteri is a threatened freshwater mussel species, endemic to south-western Australia, which has suffered recent, dramatic decline in range. The density, size structure and distribution adult this species within river reaches were investigated using quadrat searches modelled against range microhabitat factors. Mussels found from 26 sites 14 different rivers at mean density 28.4 ± 2.3 individuals m ?2 . W. was highly aggregated reaches. most factors explaining substrate grain size, debris distance the riverbank, with finer substrate, presence woody proximity riverbank associated greater abundance mussels. In all where found, populations appeared be actively recruiting. However, no six sites, despite them having been recorded as present last 20 years, suggests that still decline. identification requirements for will assist identifying suitable release translocation and/or captive propagation, may required prevent extinction species.