Freshwater mussels of coastal NSW
Freshwater mussels come in various sizes but typically fit in the palm of your hand. Cucumerunio novaehollandiae (on top of hand) and Alathyria profuga (bottom of hand) are common in streams of the Hunter-Central rivers region.
Photo: Kerry Wilson
Freshwater mussels are large, brown-black bivalved molluscs that live on the bottom of streams and lakes, sometimes in dense beds containing thousands of shells.
Although similar in appearance to marine mussels, the two groups have been separated for at least 200 million years and have very different biology. NSW has eight species of freshwater mussels that live in coastal streams.
The species of freshwater mussels found in Australia and New Guinea are unique to the region and are not found any where else in the world. Their closest relatives live in New Zealand and South America.
Why freshwater mussels are important for the environment
As indicators of aquatic health
Mussels live in stable environments and are sensitive to pollution so their presence indicates good conditions for other aquatic animals. They have a long life span and are sedentary, so when they disappear it is a warning that something is awry.
Dense mussel beds, such as this one in Lake Burragorang, filter large volumes of water and act as biological filters.
Photo: Becca Saunders, Penrith City Council.
Their important ecological role
Mussels filter large volumes of water to extract their food, removing nutrients, algae, bacteria and organic detritus from the water. Mussel waste products are food for other animals and they, in turn, are food for water rats and platypus.
Their significant cultural value
Freshwater mussels were an important source of food for Indigenous Australians. Middens containing large numbers of mussel shells are widespread alongside rivers and lakes. Aboriginals also used mussel shells as tools.
Where do mussels live in coastal NSW?
Mussels are most likely to be found in the middle or lower sections of permanently flowing streams. However, floodplain mussels (Velesunio ambiguus) are an exception; they can be found in temporary creeks and ponds, including farm dams, and avoid strongly flowing rivers.
The stability of the stream bed is critical for mussels and the best habitats provide protection from scouring flows. These places have dense streamside vegetation and lots of large woody debris or boulders in the channel to stabilise the streambed sediments and provide refuges in times of flood. This is why mussels are usually patchily distributed within a section of stream. Shade from streamside vegetation helps to stabilise water temperatures and ameliorate water quality by shielding the stream from the sun.
Juvenile mussels spend the first few years of life within the stream bed so streambed stability and sediment quality are important determinants of juvenile habitat. Organic sediments and places where the stream bed is clogged with fine silt are unfavourable for juvenile mussels.
Find out more...
Mussel Watch WA 2011, Klunzinger M, Lymbery A, Morgan D, Beatty S, Mussel Watch WA, Murdoch University, Perth
The Mussel Project: MUSSELp is devoted to the evolution and taxonomic relationships of freshwater mussels and contains information and images of mussels from around the world.
Freshwater Mollusk Conservation Society is devoted to public education and conservation of North American freshwater molluscs although the information has wider relevance. It includes information on mussel biology and conservation including some fascinating videos of the lures and mimicry used to attract potential fish hosts.
Strayer DL 2008, Freshwater Mussel Ecology: A Multifactor Approach to Distribution and Abundance, University of California Press, Berkeley.
Walker KF 1998, Molluscs of inland waters, In: Beesley PL, Ross GJB, Wells A. (eds). Mollusca: The Southern Synthesis, Fauna of Australia, CSIRO Publishing, Melbourne.
Walker KF, Byrne M, Hickey CW, Roper DS 2001, Freshwater mussels (Hyriidae) of Australasia, In: Bauer G, Wachter K. (eds). Ecology and Evolution of the Freshwater Mussels Unionoida, Springer, Berlin.
This project has been supported by the NSW Government's Environmental Trust.
Page last updated: 06 September 2011