title: What do qualitative rapid assessment collections of macroinvertebrates represent? A comparison with extensive quantitative sampling.
abstract: It is a fundamental tenet of Rapid Biological Assessments (RBA) that the samples collected reflect the community from which they are drawn. As with any biological sampling, RBA collections are subject to sampling error resulting in the omission of some taxa. The aim of this study is to compare the composition of RBA samples with an estimate of community structure based on extensive quantitative sampling. We used logistic regression to explore the relationships between the frequency of a taxon being collected in an RBA sample and its biological and ecological traits, namely its abundance, distribution, body size and habit. RBA samples and quantitative estimates of community structure were made in riffles in the Kangaroo and Nepean Rivers, New South Wales, Australia. Single RBA samples may collect up to 63% of the taxa that are collected by extensive quantitative sampling at a site. The frequency of a taxon being recorded in an RBA sample was significantly and positively related to all traits tested indicating a bias in the collection methods towards large, abundant and widely distributed taxa. Accordingly, taxa missed by RBA sampling were generally small, narrowly distributed or rare. These findings enhance our understanding of what RBA samples represent, and the bias and source of errors associated with RBA sampling. This study also quantifies the utility of RBA methods for biodiversity assessment.
authors.affiliation: Department of Environmental Sciences and Institute for Water and Environmental Resource Management, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia.
authors.forename: C L
authors.initials: CL
authors.lastname: Gillies
authors.forename: G C
authors.initials: GC
authors.lastname: Hose
authors.forename: E
authors.initials: E
authors.lastname: Turak
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D007448:Invertebrates; D009517:New South Wales; D012494:Sampling Studies