Monday, May 26, 2008 - 4:00 PM
95

A comparison of techniques for the biomonitoring of deep rivers

J. Iwan Jones, Martin W. Neale, Jon A.B. Bass, John H. Blackburn, Tracy A. Corbin, Rick J. M. Gunn, Nick T. Kneebone, John Davy-Bowker, and Ralph T. Clarke. CEH, c/o Freshwater Biological Association, East Stoke, Wareham, BH20 6BB, United Kingdom

Sampling deep rivers is inherently more difficult, hazardous and time-consuming than sampling shallow rivers. Standard kick-sample techniques are not suitable. The efficiency, effectiveness, precision, and cost-effectiveness of four techniques for sampling macroinvertebrates in deep rivers (long handled pond net, dredge, marginal sample and air-lift) were tested in a number of Irish rivers. Where possible the techniques were compared to standard shallow water (kick-sample) techniques. The air-lift was the most effective, overall the most precise, and the most cost-effective technique. The light dredge had no power to detect differences among sites, implying that it also cannot detect change within sites. Thus, it was effectively useless. The samples collected from the margin contained a large but partly different, less sensitive (i.e. lower BMWP scoring), component of the fauna than those collected by the airlift. The component of the fauna found in the margin did not respond to differences among sites in the same way as that found in the river channel, and appeared to be sensitive to different pressures. The samples collected from the margin were least representative of the site as a whole, particularly in wider rivers. The airlift also produced samples that were most similar to a standard kick sample.


Web Page: non-wadeable rivers, sampling techniques, deep rivers

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