Osmoregulation in populations of an endangered hardyhead (Atherinidae: Craterocephalus fluviatilis McCulloch, 1912) from different salinity regimes |
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| Authors: | S D Wedderburn K F Walker |
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| Institution: | School of Earth and Environmental Sciences DX650 312, The University of Adelaide, SA, Australia |
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| Abstract: | Abstract – Fragmented populations of freshwater fish may develop genotypic and phenotypic differences as adaptations to local habitat conditions. These differences contribute significantly to biological diversity and may lead to speciation. In the Murray–Darling Basin, Australia, the Murray hardyhead Craterocephalus fluviatilis, listed as ‘endangered’ by the World Conservation Union, has a wide but fragmented distribution that is apparently related to salinity. To determine whether this pattern has a physiological basis, we compared osmoregulation in fish from two isolated populations in different salinity regimes (Wyndgate: 0.4–1.5‰; Disher Creek: c. 1.0–45‰). In laboratory trials, fish from both populations remained healthy at high salinities (5–65‰). The Disher Creek population maintained a significantly lower blood osmotic concentration than the Wyndgate population at salinities ≤1‰, suggesting that there is a physiological difference between them. The findings have implications for the conservation of C. fluviatilis and other fish populations whose distributions are fragmented by salinity. |
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| Keywords: | fragmentation conservation salinity Craterocephalus fluviatilis Atherinidae Murray– Darling Basin |
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