Effects of artificial freshets on substratum composition, benthic invertebrate fauna and invertebrate drift in two impounded rivers in mid-Wales
✍ Scribed by J. Scullion; A. Sinton
- Publisher
- Springer
- Year
- 1983
- Tongue
- English
- Weight
- 534 KB
- Volume
- 107
- Category
- Article
- ISSN
- 1573-5141
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✦ Synopsis
Artificial discharges of water from reservoirs caused a six-fold and three-fold increase in discharge in the R . Tywi and R . Elan respectively but did not significantly alter particle size composition (by weight) and the porosity of the substratum or the organic matter content of fine particles (<0 .5 mm). Freshets in both rivers resulted in a consistent, though not significant, reduction in total densities of invertebrates and the densities of many major taxa and abundant species . During the freshet in the R . Elan, maximum concentration and total load of suspended solids were about 11 and 35 times greater than pre-release values respectively while invertebrate drift was dominated by Chironomidae (65%) and Plecoptera (25%) . Total numbers and densities of drifting chironomids increased immediately in response to the flow increase ; in contrast, numbers and densities of plecopterans increased later, during the night .