Effects of Chlorpyrifos on a Microecosystem

Abstract

A recirculating aquatic microecosystem consisting of three subsystems and with a total volume of 7.5 L was used to study effects of the insecticide chlorpyrifos. The three subsystems represent the trophic levels of primary producers (algae), herbivores (Daphnia magna), and decomposers (bacteria on a sand filter). Two of four microecosystems were perturbed with chlorpyrifos 429 d after they were started. All subsystems were monitored weekly for several chemical and biological variables. The response of the systems was followed for 130 dafter chlorpyrifos application. An immediate decrease of the Daphnia population could be explained from the mortality observed in single species tests. The population recovered within two weeks. Two weeks after the introduction of chlorpyrifos, the pH in all subsystems dropped by about two units. Concurrent with the pH changes, there were changes in the algal biomass, the Daphnia numbers, and the oxygen concentrations. The pH in the treated systems was comparable to the controls about 90 d after the treatment, but the other variables did not recover. These effects were not predicted by any single-species test and, therefore, represented ecosystem effects.

Ecological impact of repeated applications of chlorpyrifos on zooplankton community in mesocosms under Mediterranean conditions

“…These results are in accordance with those of previous studies using chlorpyrifos in micro and mesocosms (Stay et al 1989; Van den Brink et al 1995, 1996Van Wijngaarden et al 2005a). Based on previous laboratory experiments ( Kersting and Van Wijngaarden 1992;Van Wijngaarden et al 1993), a reduction close to zero of D. gr. galeata was expected three weeks after the first insecticide application.…”

Ecotoxicology of Chlorpyrifos

“…The presence of macrophytes generally increased the response time for ecological effects of the model ecosystems (Brock et al 1992a). Kersting (1991), Kersting and Wijngaarden (1992), and Leeuwangh et al (in manuscript) evaluated the effects of chlorpyrifos (0.64 or 0.67 ",giL nominal) dosed into recirculating microcosms containing algae, daphnids, and bacteria. Microcosms recirculated for 212 d before chlorpyrifos dosing showed only limited changes in species abundance relative to control micro-cosms (Kersting 1991).…”

“…Microcosms recirculated for 429 d before chlorpyrifos dosing exhibited changes in relative species abundance for at least 130 d (Kersting 1991). Algal abundance and system pH declined approximately 3 wk following dosing and remained reduced for 130 d (Kersting and Wijngaarden 1992). Daphnid abundance decreased following dosing, then recovered within 2 wk once the chlorpyrifos concentration declined below 0.1 ",giL.…”

Effects of the insecticide dursban® 4E (active ingredient chlorpyrifos) in outdoor experimental ditches: I. Comparison of short‐term toxicity between the laboratory and the field

“…This article compares laboratory single-species toxicity tests with the short-term fate and effects of chlorpyrifos in our most complex test system. Mesocosms resembling drainage ditches were treated with a single application of chlorpyrifos in a regression design.Comparisons between laboratory single-species toxicity tests and test systems of intermediate ecological complexity have already been dealt with [6][7][8][9][10].…”