title: Variability in the identification and enumeration of marine benthic invertebrate samples and its effect on benthic assessment measures.
abstract: Studies designed to measure anthropogenic impacts on marine benthic communities depend on the ability of taxonomists to consistently discriminate, identify, and count benthic organisms. To quantify errors and discrepancies in identification and enumeration, 20 samples were completely reprocessed by another one of four participating laboratories. Errors were detected in 13.0% of the data records, affecting total abundance by 2.1%, numbers of taxa by 3.4%, and identification accuracy by 4.7%. Paired t-tests were used to test for differences in the Benthic Response Index (BRI), total abundance, numbers of taxa, and the Shannon-Wiener index between the original and the reanalysis data. Differences in the BRI were statistically insignificant. Although statistically significant differences were observed for numbers of taxa, total abundance, and the Shannon-Wiener index, the differences were small in comparison to the magnitude of differences typically observed between anthropogenically affected and reference sites.
authors.affiliation: Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683-5218, USA. anandar@sccwrp.org
authors.forename: J Ananda
authors.initials: JA
authors.lastname: Ranasinghe
authors.forename: David E
authors.initials: DE
authors.lastname: Montagne
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Weisber
authors.forename: Mary
authors.initials: M
authors.lastname: Bergen
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Velarde
mesh_terms: D000818:Animals; D002965:Classification; D004784:Environmental Monitoring / Q000592:standards*; D007448:Invertebrates; D015588:Observer Variation; D011157:Population Dynamics; D011786:Quality Control; D015203:Reproducibility of Results; D013048:Specimen Handling; D014873:Water Pollutants / Q000009:adverse effects
chemical_list: D014873:Water Pollutants