An Evaluation of the Use of a Basket-Type Artificial Substrate for Sampling Macroinvertebrate Organisms
- 1 July 1971
- journal article
- Published by Oxford University Press (OUP) in Transactions of the American Fisheries Society
- Vol. 100 (3) , 553-559
- https://doi.org/10.1577/1548-8659(1971)100<553:aeotuo>2.0.co;2
Abstract
The results obtained from the use of bottom, basket type, artificial samplers, were analyzed statistically to determine the samplersˈ efficiency in collecting aquatic macroinvertebrates. Two ecologically similar riffle stations located near McCoy, Virginia on the New River were chosen for this evaluation. Based on an analysis of the number of taxa collected, 15 basket samplers at Station 1 showed a range of seven taxa with a coefficient of variation of 11.6%. Station 2, located 500 yards upstream, with 16 samplers, had a range of 11 taxa with a coefficient of variation of 16.29%. In an evaluation of the number of specimens collected, Station 1 had a range of 39 specimens with a coefficient of variation of 10.9%. Station 2 had a range of 103 specimens which was larger than the average of 85.6 specimens per sampler. To be 95% confident that the mean community structure indices for each station [Sequential Comparison Index and diversity per individual ()] were within 25% of their true value, only two basket samplers were needed. However, four samplers at Station 1 and six samplers at Station 2 would be required for the number of taxa collected. Due to unequal distribution of macroinvertebrates on the bottom, or sampling design bias, 21 samplers at Station 2 would be required to be 95% confident that the mean number of specimens collected was within 25% of its true value. An estimate of the proportion of taxa which would have been detected on the average by a smaller number of basket samplers showed that at least five basket samplers were necessary at each station in order to be 95% confident that at least 50% of the total number of taxa were collected. When using this type of substrate sampler for collecting macroinvertebrates in a comparison of the biological water quality between selected stations, the number of taxa collected by the samplers and the community structure of the macroinvertebrates are less variable than the number of specimens obtained. These types of analyses can serve as the basis for establishing the appropriate number of samplers for a routine survey.Keywords
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