ISSN:
1573-5117
Keywords:
Chironomus tentans
;
particle Size
;
sediment toxicity tests
;
biological endpoints
;
behaviour
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1003159323259
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