HR: 09:30h
AN: NB51F-05    [Abstracts]
TI: Wanted Dead or Alive?
AU: * Vlek, H E
EM: hanneke.vlek@wur.nl
AF: Alterra, P.O. Box 47, Wageningen, 6700 AA Netherlands
AB: A European standard has recently been developed for the sampling of macroinvertebrates in streams. The method for sorting macroinvertebrate samples, however, is still a major point of discussion. The goal of this study was (1) to determine whether preserved and unpreserved samples show significant differences in metric and bioassessment results and (2) to compare the cost efficiency of both protocols. Data from three streams in the Netherlands were collected. In each stream six replicate samples were taken with a pond net. A replicate can be described as a composite sample from several habitats at a site. Three replicates were fixed in formalin directly after sampling. The remaining replicates were not fixed. All samples were transported to the laboratory for sorting. The samples with live organisms were kept in a refrigerator until sorting was undertaken. Sorted organisms were preserved in ethanol and later identified to species level. Of the 58 metrics examined, only nine showed significant differences between protocols. Assessment results differed in only one out of six cases. No significant differences in the total time (costs) for sample processing were detected. Overall the effects of differences between replicates were larger than the effects due to differences in protocol.
DE: 6304 Benefit-cost analysis
DE: 9335 Europe
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly