Freshwater mussels are among the most threatened groups of aquatic animals in the world and face multiple threats including habitat modification, climate change, and altered water quality. Importantly as organisms, they have been shown to provide a range of ecosystem services, through biofiltration & nutrient recycling and indirectly, by acting as bio indicators. Bioindicators are living organisms ranging from microbes, through to complex animals, which are utilised to monitor of the health of the environment and any changes through time.
Carter’s freshwater mussel (Westralunio carteri) has long been recognised as the only species of freshwater mussel in south-western Australia. The species, like other freshwater mussels, has a complex life cycle including a parasitic larval stage which requires a freshwater fish host. The larvae, known as glochidia, are released in thick strands of mucus, and subsequently attach to a fish host (typically on the fin or gills of fish) for several weeks. During this time they metamorphose into the juvenile form prior to dropping off the fish host (Klunzinger et al., 2013). In 2018 this species was listed as ‘Vulnerable’ under the Environment Protection and Biodiversity Conservation Act 1999 (Commonwealth) and the Biodiversity Conservation Act 2016 (Western Australia). Research has identified that the species has undergone a 49% reduction in extent of occurrence due primarily to secondary salinization (Klunzinger et al., 2015). This declining trend has also been seen in a range of other freshwater mussel species from Mediterranean climate regions around the globe. They are now typically found within 50–100 km of coastal south-western Australia, and often occurs in greatest abundance in slower flowing waters where sediments are soft enough to allow the species to burrow. The species current range is between Gingin Brook in the north to the Kent, Goodga and Waychinicup Rivers in the South. Fascinatingly, however, recent research suggests that this individual species, may actually represent two/possibly three species/sub-species. DNA analysis suggests there are three evolutionary significant units, including western and southern lineages and a south-western subspecies (Klunzinger et al., 2021). This in turn may have significant conservation implications for the species. Despite the key role freshwater mussels play in the ecosystem, a number of key knowledge gaps remain, including for Carter's freshwater mussel. For example, what is the filtering capacity of this species? What are its tolerances to pollutants from urban, agricultural and industrial environments? There is always room for further research, particularly for threatened species, and through time, hopefully the answers will help conserve this iconic species. Links:
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AuthorMy name is Garry and I am extremely passionate about the environment. I have completed my BSc. Conservation and Wildlife Biology with First Class Honours and have worked in the Environment sector since 2009. Archives
September 2019
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