Life cycle and behavioural assessments of the influence of substrate particle size on Chironomus tentans (Diptera : Chironomidae) in laboratory assays

• Published in: Hydrobiologia Vol. 361; no. 1-3; pp. 1 - 9
• Main Authors: SIBLEY, P. K, BENOIT, D. A, ANKLEY, G. T
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 1997; Springer Nature B.V
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Food supply; Fundamental and applied biological sciences. Psychology; Grain size; Larvae; Larval development; Life cycle analysis; Particle size; Sediments; Soil testing; Substrates; Survival; Chironomidae; Particle size; Bioassay; Chironomus tentans; Toxicity; Insecta; Sediments; Grain size distribution; Substrate; Life cycle; Test; Arthropoda; Invertebrata; Diptera
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1023/a:1003159323259

Identifying and understanding factors that affect interpretation of sediment toxicity is critical to the development and standardization of sediment test methods. In this study, we evaluated the influence of sediment particle size on survival, growth, emergence, and reproduction in a life cycle test with the midge Chironomus tentans, and on substrate selection behaviour of C. tentans larvae. In the life cycle assessment, larval development was followed for one generation on six substrates with mean particle sizes of 8, 146, 218, 306, 448, and 592 μm. For behavioural tests, first and third instar larvae were provided with a choice between paired substrates, with and without equal quantities of food. Survival of larvae at 20 d was not affected by particle size; however, survival of larvae at test completion was significantly reduced (65.6%) in the 8 μm substrate. Larval growth was not systematically related to particle size. Total emergence was significantly lower in the 8 and 592 μm substrates (50 and 53.1%, respectively) relative to the other substrates, reflecting the lower survival in these treatments. In addition, time to first emergence was significantly longer, and the rate of emergence depressed, in the 8 μm treatment. Reproductive output (mean eggs/female) was not significantly different among substrates, although fewer egg masses were produced in the 592 and 8 μm substrates. In behavioural tests, third instar larvae exhibited a weak preference for the smaller of two grain sizes when food was equally available, but this was not systematically related to the absolute difference in mean grain size. In contrast, first instar larvae consistently selected the smaller of two grain sizes when food was equally available; for these larvae, substrate selection was significantly correlated with the absolute difference in mean grain size. When food supply differed between substrates, a significantly higher proportion of both first and third instar larvae selected the substrate with food, independent of particle size. Together, the life cycle and behavioural data from this study suggest that sediment particle size, by itself, should not significantly influence interpretation of the results of toxicity tests with C. tentans.[PUBLICATION ABSTRACT]