Fate and effects of the insecticide Dursban® 4E in indoor Elodea-dominated and macrophyte-free freshwater model ecosystems: I. Fate and primary effects of the active ingredient chlorpyrifos

Abstract

The fate of the insecticide Dursban 4E (active ingredient chlorpyrifos) and its effect on crustaceans and insects was studied in indoor experimental freshwater ecosystems that intended to mimick drainage ditches. A single dose (simulating aerial drift) was applied to achieve nominal chlorpyrifos concentrations of 5 or 35 micrograms/L. Two experiments were performed, one in which all model ecosystems were dominated by the macrophyte Elodea nuttallii, and one using systems devoid of macrophytes. In macrophyte-dominated systems, Elodea vegetation adsorbed a large proportion of the dose applied and hampered the mixing of the insecticide in the water (at least up till day 8). Only a small proportion became incorporated in the sediment. In open water systems the insecticide was rapidly mixed in the water, and the sediment played a very significant role as sink for chlorpyrifos. In both Elodea-dominated and open water systems 50% of the dose applied had disappeared on day 8 post-treatment. The rate of disappearance of chlorpyrifos was relatively rapid in water and macrophytes, and relatively slow in the sediment. Of the arthropods in the zooplankton Cladocera were more susceptible than Copepoda. Significant effects (p less than or equal to 0.05) on Cladocera occurred relatively late in Elodea-dominated systems (in week 4 post-application) in contrast to open water systems (week 1), which is in accordance with the observed differences in the fate of chlorpyrifos. Daphnia pulex, D. longispina and Simocephalus vetulus recovered in the model ecosystems when chlorpyrifos concentrations were lower than 0.1-0.2 micrograms/L, which is in agreement with results of laboratory protocol tests performed with these cladocerans. Among the macroscopic Arthropoda the apparent order of susceptibility was amphipods greater than insects greater than isopods. The isopod Asellus aquaticus was more sensitive to the application of the insecticide than the closely related species Proasellus coxalis. In treated open water systems the latter even increased significantly in numbers. Cage experiments in the model ecosystems performed with several species of Arthropoda indicate that laboratory protocol tests may give a reasonable prediction of short-term direct effects of chlorpyrifos for the same species inhabiting more complex aquatic systems.

Invited Review - Fight on Plankton! or, Phytoplankton Shape and Size as Adaptive Tools to Get Ahead in the Struggle for Life

“…Communities may build up resistance against pollution (pollution-induced community tolerance: Blanck et al, 1988) or even ÂmemoriseÊ stress they have undergone in the past (community conditioning hypothesis: Matthews et al, 1996). The community scale of research does not only reveal the direct effects of stress on the community (Brock et al, 1992a), but also about secondary effects (Brock et al, 1992b) and altered ecosystem functioning due to these changes (Brock et al, 1993). The second category is about the role of biodiversity for the functioning of communities and ecosystems.…”

“…The current design of the Limnotrons is mostly based on experiences with 3 existing types of laboratory ecosystems. The idea for a series of cosms was derived from cosms used at the Wageningen University and Research Centre, Wageningen, the Netherlands (Brock, 1992a). The illumination and impeller design were derived from the cosms at the Netherlands Institute for Sea Research, Êt Horntje, The Netherlands .…”

Mitigating with macrophytes: Submersed plants reduce the toxicity of pesticide‐contaminated water to zooplankton

“…In one study, which compared the ecological effects of the organophosphate insecticide chlorpyrifos (35 mg/L) between macrophyte-dominated and phytoplanktondominated artificial test systems ($0.85 m 3 ), Brock et al [24] found that cladocerans were eliminated within hours in the phytoplankton-dominated system. In contrast, it took several weeks for die-offs to occur in the macrophyte-dominated system.…”

“…For example, Brock et al [24] compared the effects of chlorpyrifos on aquatic communities inhabiting macrophyte-dominated systems in 1988 with the effects of chlorpyrifos on similar (but not identical) communities inhabiting open-water systems in 1989. In addition, Roessink et al [25] examined the response of macrophyte-and phytoplanktondominated communities that differed in nutrient environment and species composition.…”

Ecological Effects of Spring and Late Summer Applications of Lambda-Cyhalothrin on Freshwater Microcosms

“…Changes in these conditions may influence the fate and bioavailability of compounds. Brock et al (1992), for example, showed for chlorpyrifos that the mixing of the compound through the water column was strongly influenced by the vegetation structure in microcosms. For lambda-cyhalothrin, it has been demonstrated that different densities of macrophytes can have considerable influence on the fate and bioavailability of this compound (Hand et al 2001;Leistra et al 2003).…”