Relative sensitivity of Chironomus tentans instars to various toxicants

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:49548

Norberg-King, T J; Juenemann, P S ^[1]; Juenemann, J L ^[2]

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1. Environmental Protection Agency, Duluth, MN (United States). Environmental Research Lab.
2. Science Applications International Corp., Duluth, MN (United States)

During the recent efforts by the US Environmental Protection Agency to standardize the sediment toxicity test methods, the authors conducted experiments to evaluate the influence of instar on the sensitivity of C. tentans to seven toxicants with varying modes of action. These experiments consisted of water only 96 h acute toxicity tests using C. tentans larvae that were 4-d, 6-d, 8-d, 10-d, and 12-d post-hatch. These ages covered the first, second, third, and fourth instar stages. Toxicants used were copper, nickel, zinc, potassium chloride, diazinon, a surfactant, and ammonia. Each acute test was also conducted using larvae cultured on two different amounts of the same Tetrafin{reg_sign} food. For the type of toxicant, differences in the sensitivity were observed with respect to the age of the animals for the two feeding levels. However, the overall age-specific difference was variable for the type of toxicant. For most of the toxicants, the LC50s varied by 50% or less among the ages tested for either feeding level while the older animals were more sensitive to the surfactant tested yet for potassium chloride the fourth instar was the least sensitive. The trends observed will be discussed. Additional information on identifying the instar and useful measurements will be discussed.

• OSTI ID: 49548
• Report Number(s): CONF-9410273--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
AMMONIA
COPPER
DIPTERA
NICKEL
POTASSIUM CHLORIDES
SEDIMENTS
SENSITIVITY
SURFACTANTS
TOXICITY
WATER POLLUTION
ZINC