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Communication at the NABS Annual meeting, Keystone, 2000
(174) INFLUENCES OF ORGANIC MATTER COMPOSITION IN SEDIMENTS ON LARVAL GROWTH OF THE MIDGE CHIRONOMUS RIPARIUS.
J. Vos1, P. Van Den Brink2, J. Postma3, F. Van Den Ende1, and W. Admiraal1. 1Department of Aquatic Ecology and Ecotoxicology, University of Amsterdam, Amsterdam, Netherlands, 2Department of Water and the Environment, Alterra Research Institute, Wageningen, Netherlands, 3AquaSense Consultants, Amsterdam, Netherlands
In a project on the feeding biology of Chironomus riparius we have assessed quantitative relationships with the concentrations of chemically defined food sources. Here we present the results of a study verifying such relationships using first instar larvae that were grown on different types of field-collected sediments for 2 weeks. The sediments were analyzed for contents of organic matter, carbon, nitrogen, phosphorus, carbohydrates, protein, fatty acids, pigments and grain size distribution. Data were analyzed in detail by means of univariate correlations and multivariate analyses. Composition of sediment organic matter was identified as generally limiting factor for larval growth. Larval growth and survival were positively correlated with carbohydrates, phosphorus and polyunsaturated fatty acids. Negative correlations were found with organic matter content, grain size of > 210 µm and with C/N ratio. Preliminary analysis of variables expressed as percentages of organic matter content resulted in more significant correlations than variables expressed as percentages of dry weight. Both this discrepancy and the negative correlation of growth rate with grains > 210 µm indicate that the physical characteristics of the sediment conformed the definition of food concentration. This corroborates experimental findings on grain size effects on feeding in experimental studies with Chiroronomus riparius.
Presented at 4:00 PM on Tuesday, May 30, 2000 in Secondary Production and Food Webs
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