The significance of growth in Chironomus tentans sediment toxicity tests: Relationship to reproduction and demographic endpoints

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

OSTI ID:201198

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

---

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

This study assessed the biological relevance of growth, as used in sediment toxicity bioassessment, through evaluation of the relationship between growth and reproduction in the midge C. tentans. Newly-hatched larvae were fed one of six food levels (3.5, 4.0, 4.5, 5.0, 5.5, 6.0 mg Tetrafin fish food) on a daily basis for one complete generation. Larvae were exposed in 300 ml beakers containing 100 ml of 75/{micro}m sand housed within an intermittent water renewal system. Food supply had no effect on larval (65--82%), pupal (93--95%), or adult (90--98%) survivorship. Larval growth and adult weight decreased significantly (p{<=}0.05) with decreasing food supply (r{sup 2} = 0.92, 0.91 respectively). The data suggest that a threshold larval dry weight of approximately 0.6 mg must be obtained for emergence to occur. This value also corresponded to the approximate minimum adult weight observed in this study. Emergence rate and total emergence were delayed at lower feeding levels; however, total emergence was not less than 60% for any treatment. Egg mass production, oviposition rate, and mean number of eggs produced per female declined significantly with reduced food supply. Larval growth and adult weight were significantly correlated with age-specific fecundity (r{sup 2} = 0.96). Application of the reproductive data in a demographic model showed that the expected number of offspring recruited to subsequent generations declined significantly with a decrease in food supply. The results of this study demonstrate a direct relationship between growth and reproduction in C. tentans and clearly emphasize the biological and ecological relevance of the growth endpoint in sediment toxicity bioassessment.

• OSTI ID: 201198
• 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
ANIMAL GROWTH
BIOASSAY
FLIES
MATHEMATICAL MODELS
POLLUTANTS
REPRODUCTION
SEDIMENTS
TOXICITY
WATER POLLUTION