Aquatic fauna refuges in Margaret River and Cape to Cape region of Australia's Mediterranean-climatic Southwestern Province

Margaret River and the Cape to Cape region in the extreme south-western tip of Australia are located between Cape Naturaliste in the north and Cape Leeuwin in the south and encompass all intervening catchments that drain westward to the Indian Ocean. The region has a Mediterranean climate and houses 13 native, obligate freshwater macrofauna species (i.e. fishes, decapod crustaceans and bivalve mollusc), four of which are listed as threatened under State and/or Commonwealth legislation. The most imperiled species are the Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Hairy Marron (Cherax tenuimanus), both of which are endemic to the Margaret River catchment and listed as critically endangered (also by the IUCN), and Balston's Pygmy Perch (Nannatherina balstoni) which is vulnerable. The region also houses several fishes that may represent new, endemic taxa based on preliminary molecular evidence. Freshwater ecosystems in the region face numerous threats including global climate change, a growing human population, introduced species, destructive land uses, riparian degradation, water abstraction, declining environmental flows, instream barriers, and fire. Here we review the current knowledge of the considerable aquatic biodiversity values of the region to provide a contemporary checklist, and to highlight actions that may be considered to protect these values in the face of both current and future conservation threats.