The Fate and Effects of Guthion (Azinphos Methyl) in Mesocosms

• Published in: AQUATIC MESOCOSM STUDIES in ECOLOGICAL RISK ASSESSMENT pp. 469 - 495
• Main Authors: Giddings, Jeffrey M., Biever, Ronald C., Helm, Raymond L., Howick, Gregory L., deNoyelles, Frank J.
• Format: Book Chapter
• Language: English
• Published: CRC Press 1994
• Edition: 1
• Subjects: Benthic Samples; Azinphos Methyl; Emergent Samples; Ecological Risk Assessment; Highest Treatment Level; Exposure Levels; Juvenile Bluegill; Benthic Macroinvertebrates; Bluegill Sunfish; Taxonomic Abundance; Rotifer Densities; Emergent Adult; Laboratory Toxicity Tests; Average Concentration Peak; Family Chironomidae; Adult Bluegill; Mixing Tank; Control Mesocosms; Oxygen Analog; Organophosphorus Insecticide; Exposure Response Trends; NOEC; Zooplankton Abundance; Juvenile Number
• ISBN: 9780873715928; 0873715926
• DOI: 10.1201/9781003070016-30

We measured the ecological effects of an organophosphorus insecticide, Guthion, in 12 tenth-acre pond mesocosms. The ponds received Guthion at five exposure levels selected to bracket the toxicity range for aquatic biota. Treatments were repeated eight times at weekly intervals in a manner simulating agricultural runoff. Guthion residues disappeared from the water nearly completely within 1 week of each application. We interpreted Guthion effects by examining exposure-response relationships to identify a response threshold (the EC0, determined by linear regression) for each taxon. Overall, fish and certain groups of insects were the most sensitive components of the ecosystem to Guthion. Other insects, as well as cladocerans and rotifers, were less sensitive, but higher Guthion exposure levels reduced their abundance. Copepods, snails, and plants were unaffected, and some of these groups increased in response to the loss of fish and invertebrate predators and competitors. Mesocosm results generally agreed with laboratory toxicity data.