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Doctoral thesis, 2000

Spatial and temporal variability of stream benthic macroinvertebrates

Sandin, Leonard

Abstract

This thesis describes the spatial and temporal variability of benthic macroinvertebrate communities in Swedish streams and its implications for environmental assessment. One of the challenges for environmental assessment is to separate change caused by anthropogenic stress from natural variability, therefore it is essential to have insight in the effects of temporal and spatial variability on the benthic macroinvertebrates. The thesis is based on two stream riffle datasets; one spatial (694 streams) and one temporal (6-11 years sampling of five streams). Classification of macroinvertebrate community composition showed a gradual change in community composition in Sweden. A geographical (ecoregional) classification was tested as a starting point for biomonitoring, but I found that local-scale variables such as stream velocity and substratum type were important descriptors and must be taken into account in assessments of running waters. Despite that temporal variability was small relative to the spatial variability, I argue that the temporal variability is of importance and that the inherent cyclic and seasonal factors affecting benthic macroinvertebrates has to be accounted for in environmental assessment. Surprisingly, the stream macroinvertebrate community composition did not show a largescale pattern (correlation with the limes norrlandicus ecotone, found at ~60° north), whereas a lake dataset showed such a pattern. I speculate that differences between the two ecosystems are caused by differences in detrital retention and stability. Richness indicator measures generally had low variability and high statistical power and needed few samples to detect changes caused by perturbation. In environmental assessment it is important to know what effect size and variability (spatial and temporal) one can expect from an indicator metric (and hence the macroinvertebrate community) so that the money spent in impact studies is used in a cost-effective way.

Keywords

ecosystems; invertebrates; benthos; rivers; water resources; environmental impact assessment; bioassays; monitoring; indicator animals; seasonal variation; sweden

Published in

Acta Universitatis Agriculturae Sueciae. Silvestria
2000, number: 172
ISBN: 91-576-6056-5
Publisher: Department of Environmental Assessment, Swedish University of Agricultural Sciences

Authors' information

Sandin, Leonard
Swedish University of Agricultural Sciences, Department of Environmental Assessment

UKÄ Subject classification

Environmental Sciences
Oceanography, Hydrology, Water Resources
Ecology

URI (permanent link to this page)

https://res.slu.se/id/publ/54457