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Improving study designs for assessing forestry impacts on the giant freshwater crayfish, Astacopsis gouldi


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Pracejus, AM 2016 , 'Improving study designs for assessing forestry impacts on the giant freshwater crayfish, Astacopsis gouldi', Honours thesis, University of Tasmania.

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This survey aimed at correlating the abundance of Astacopsis gouldi, the world's largest freshwater crayfish, with two different plantation types in Northern Tasmania. After a pilot study revealed inherent difficulties in relying on conventional methods to select suitable sampling sites, selection criteria were refined and ultimately improved through the use of species distribution modelling (MaxEnt). Accumulated mean annual run-off and mean annual rainfall stood out as important in the model and helped to reduce the proportion of intermittent streams in the data set. Analyses conclude that there is no observable plantation effect that correlates with crayfish abundance; however, this should be taken with caution because the sample size was too small to detect a potential effect on crayfish abundance. As a result, approximately 15-18 sites are recommended to be used per tested group. A classification tree further suggests that the presence of undercut banks, log jams and submerged logs might constitute important mesa-habitat features that should require further analysis in the future. The study is thus more recommendative in nature and should assist future researchers to develop effective sampling strategies to address the difficulties inherent in assessing crayfish abundance in plantation streams.

Item Type: Thesis - Honours
Authors/Creators:Pracejus, AM
Keywords: crayfish, forestry, species distribution modelling, Maxent, sedimentation, forestry impacts
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Copyright 2016 the author

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