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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in Population Ecology 1
Importance of connectivity for determining biological responses to stream habitat rehabilitation: evidence from genetic and stable isotope data for selected stream fauna
B.D. Cook, J.M. Hughes, and S.E. Bunn. Cooperative Research Centre for Freshwater Ecology, Centre for Riverine Landscapes, Griffith University, Nathan, Queensland 4111 Australia
Connectivity of stream fauna throughout river systems is influenced by their dispersal ability, the architecture of the drainage, and the amount of relief between headwater and lowland reaches. Barriers to connectivity result in demographic isolation of subpopulations, and patterns of connectivity can be used to infer the likely scale at which various taxa will respond to habitat patch dynamics, including rehabilitation. We sampled taxa with contrasting dispersal abilities, freshwater shrimp (Paratya australiensis), southern pygmy perch (Nannoperca australis) and mountain galaxiids (Galaxias olidus), from sites in different tributaries and from upland and lowland reaches within tributaries. Connectivity between sites was determined by examining the partitioning of variation in mitochondrial DNA and nuclear DNA markers, and in signatures of stable isotopes of nitrogen and carbon. All taxa, regardless of their dispersal ability, were subdivided between tributaries, suggesting that each tributary contains distinct subpopulations. In contrast, connectivity within tributaries reflected expectations based on dispersal ability: G. olidus was structured the least, N. australis had varying levels of subdivision, and P. australiensis was strongly subdivided. Results suggest that multiple, small scale rehabilitated habitat patches within and between tributaries are likely to generate the greatest biological response at both patch and landscape scales.
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