Macroinvertebrate colonisation of perspex artificial substrates for use in biomonitoring studies

Abstract

Perspex multiplate artificial substrates were deployed in the Ohinemuri River on two occasions from May to November 1987. A pilot study was conducted to compare the fauna on substrates with that occurring naturally in the benthos, and a second study to investigate the colonisation dynamics. In general, the fauna on artificial substrates was similar to that of natural benthic samples, but with a greater macroinvertebrate density and total taxa number, and dominated by Austrosimuliwn australense and Chironomidae larvae. Colonisation stabilised after 28 days, after which there was little change in diversity. In contrast, equitability decreased, reflecting the greater contribution from A. australense and Chironomidae. There was a steady build‐up of fine particulate organic matter (FPOM) on the perspex surface. The relatively low exposure time necessary for equilibrium levels to be reached was attributed to the distinctive characteristics of the New Zealand aquatic fauna. The artificial substrates were slightly more variable in their density estimates than was the natural benthic sampler, but were considered suitable for collecting macroinvertebrates for biomonitoring studies where conventional techniques are impractical or inappropriate, and the stated aims of the use of artificial substrates are clearly defined.