A Comparison of Methods for Estimating Relative Abundance of Grapsid Crabs Article Received: 27 January 2004 Accepted: 18 October 2004 DOI:
Cite this article as: Kent, C.P.S. & McGuinness, K.A. Wetlands Ecol Manage (2006) 14: 1. doi:10.1007/s11273-004-5075-6 Abstract
Grapsid crabs are one of the most common, and potentially important, elements of the mangrove fauna but relatively little information is available on patterns in their distribution and abundance. In part, this may be due to difficulties in estimating the abundance of burrowing species. By not having reliable methods of estimating changes in distribution and abundance of crabs, ecological impacts of crabs may be greatly underestimated. We tested several methods for estimating the apparent abundance of eight species of grapsids in a north Australian mangrove forest. These methods included continuous and instantaneous visual counts at two distances, two types of pitfall traps and photography. We also excavated crabs to test the reliability of the best of these methods. Overall, pitfall traps equipped with funnels proved most useful, although these did preferentially capture larger crabs. An exception was the large crab,
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