Particle size as a modifying factor in sediment toxicity tests: Effects on growth, reproduction, and behavior in Chironomus tentans

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:372557

Sibley, P K; Benoit, D A; Ankley, G T ^[1]

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1. Environmental Research Lab., Duluth, MN (United States)

The potential for sediment grain size to interfere with the assessment of sublethal endpoints in sediment toxicity tests was evaluated using the midge C. tentans. Substrates, ranging in mean grain size from < 10 (clay) to 600 {micro}m, were used to evaluate growth in 2 and 10-day old larvae (10-day growth tests) and reproduction using newly hatched larvae (monitored through one complete generation). In a separate study, substrate selection behavior was evaluated using pair-wise choice experiments. Survivorship (> 85%) was not affected by grain size in any of the tests. Larval growth (10-day tests) was highest in substrates with mean grain size between 30 and 150 {micro}m, with maximum growth occurring at 75 pm. This relationship was observed for both 2 and 10 d old larvae, but was statistically significant only for 10 d old larvae. Reproductive potential (fecundity) was correlated with larval growth, being highest in smaller grain sizes (< 150 {micro}m). In pair-wise selection tests, larvae demonstrated only a slight preference (approximately 60:40) for the smaller of two particle sizes when the two substrates were supplied with equal amounts of food. However, when food was supplied to only one of the two grain sizes, larvae were significantly more abundant on the substrate containing food, independent of particle size. When the amount of available food was reduced, the proportion of larvae occurring on fed substrates declined. It is concluded that food availability is much more important than particle size in substrate selection by C. tentans, Together, the results of this study indicate that particle size can modify growth and reproductive potential in larval C. tentans and should be included in the interpretation of sediment toxicity tests results.

• OSTI ID: 372557
• Report Number(s): CONF-9511137--; ISBN 1-880611-03-1
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOASSAY
BIOLOGICAL AVAILABILITY
BIOLOGICAL INDICATORS
BIOLOGICAL STRESS
FLIES
PARTICLE SIZE
SEDIMENTS
TOXIC MATERIALS
WATER POLLUTION