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TAXONOMIC LEVEL AND SAMPLE SIZE SUFFICIENT FOR ASSESSING POLLUTION IMPACTS ON THE SOUTHERN CALIFORNIA BIGHT MACROBENTHOS
Citation:
Ferraro, S. AND F. Cole. TAXONOMIC LEVEL AND SAMPLE SIZE SUFFICIENT FOR ASSESSING POLLUTION IMPACTS ON THE SOUTHERN CALIFORNIA BIGHT MACROBENTHOS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-90/437 (NTIS PB91177188), 1990.
Description:
Macrobenthic data from samples taken in 1980, 1983 and 1985 along a pollution gradient in the Southern California Bight (USA) were analyzed at 5 taxonomic levels (species, genus, family, order, phylum) to determIne the taxon and sample size sufficient for assessing pollution impacts on 5 measures of community structure. Two statistical designs were compared a t-test for differences between reference and impacted stations where the error term was (1) among-year variation at the reference station (impact effects design), (2) replicate (within-station) sampling error (location effects design). The estimated statistical power (1-B) to detect impacts was a function of type and magnitude of impact, level of taxonomic identification, the statistical design, and the sample size (n = number of sampling years at the reference station for the impact effects design, and n = number of replicate samples per station for the location effects design). our replicate 0.1 m2 van Veen grabs per station were needed to ensure community-wide, unbiased estimates of Shannon's, 1 -Simpson's and McIntosh's Index. Family level identification appeared to be a good choice for assessing pollution impacts at the study site as it ensured a high probability (1-B > 0.80) of detecting intermediate or larger impacts on most (impact effects design) or all (location effects design) of 5 measures of community structure when n and n > 4. he level of taxonomic identification and sample size should be considered along with other sampling variables (e.g. sample unit size, sieve mesh size) when seeking a statistically rigorous, cost-effective study design sufficient to meet pollution assessment objectives.