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The net result: evaluating species richness extrapolation techniques for littoral pond invertebrates


Andrew Foggo, School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, U.K.


1. Total species richness for an assemblage or site is a valuable measure in conservation monitoring and assessment, but protocols for sampling and species richness determination in wetland habitats such as ponds, bogs or mires remain largely unrefined.

2. Techniques for estimation of total richness of an assemblage based upon replicated sampling offer the opportunity to derive useful estimates of total richness based upon small numbers of samples, and limit sampling-derived disturbance which can be particularly problematic in small aquatic habitats.

3. We quantified the performance of eight of the most commonly encountered estimators of species richness for a variety of littoral zone macrofauna from ponds, comparing estimated richness to maximum richness derived from sampling.

4. Estimates using non-parametric techniques based on species incidence provided the most accurate and precise estimates. The estimators Chao 2 and incidence-based coverage estimator (ICE) from this category were reliable and consistent slight over-estimators; the abundance-based estimator Chao1 also performed well.

5. Species inventory based on relatively small numbers of samples might be significantly improved by use of non-parametric estimators for quantification of species richness.

6. Use of non-parametric estimators of species richness can assist biodiversity inventory by preventing erroneous rankings of habitat richness based upon observed species numbers from limited sampling.