The influence of hydrology on freshwater mussel (Bivalvia: Hyriidae) distributions in a semi-arid river system, the Barwon-Darling River and Intersecting Streams
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H.A. Jones, 2007. "The influence of hydrology on freshwater mussel (Bivalvia: Hyriidae) distributions in a semi-arid river system, the Barwon-Darling River and Intersecting Streams", Animals of Arid Australia: Out on their own?, Chris Dickman, Daniel Lunney, Shelley Burgin
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Freshwater mussels (Bivalvia: Unionoida) are a major constituent of benthic communities in lowland rivers but populations have been adversely affected by water resource development in many parts of the world. Hyriid mussels were surveyed in the New South Wales section of the Barwon-Darling River and Intersecting Streams to assess habitats, recruitment status and their suitability as indicators of altered flow regimes. Three species were detected: Alathyria jacksoni, Velesunio ambiguus and V. wilsonii. A record for V. wilsonii from the Warrego River system is the first for this species for New South Wales, although it has recently been collected in the Warrego, Paroo and Bulloo river systems in south-western Queensland. Velesunio ambiguus was widely, but patchily, distributed throughout the region and was rare in the Barwon-Darling River, where it was detected mainly in the sloughy margins of weir pools. In contrast, A. jacksoni was typically found in permanently flowing water, with large populations in the Barwon-Darling River and a patchy distribution in waterholes of the Culgoa and Birrie rivers. It was absent from sections of channel that dry during droughts and elsewhere had a strong depth zonation, being most numerous in pools on outer bends and in the thalweg. In downstream weir pools it was found only in a narrow band along the banks of the original river channel. Reduced frequency and duration of flow due to water resource development may threaten the continued existence of this species in the Culgoa River. Very few A. jacksoni had a total length below 100 mm, which may indicate a lack of recruitment, that recruitment is episodic, or that juveniles occupy different habitats from adults. Alathyria jacksoni has the potential to indicate hydrological alteration for the Barwon-Darling and Culgoa rivers. It is responsive to changes in low and zero flows caused by water resource development, but its usefulness as an indicator is hampered by a lack of understanding of the influence of hydrology on recruitment processes.