For decades, we have
known that chemicals affect human and wildlife
behavior. Moreover, due to recent technological and computational
advances, scientists are now increasingly aware that a wide variety
of contaminants and other environmental stressors adversely affect
organismal behavior and subsequent ecological outcomes in terrestrial
and aquatic ecosystems. There is also a groundswell of concern that
regulatory ecotoxicology does not adequately consider behavior, primarily
due to a lack of standardized toxicity methods. This has, in turn,
led to the exclusion of many behavioral ecotoxicology studies from
chemical risk assessments. To improve understanding of the challenges
and opportunities for behavioral ecotoxicology within regulatory toxicology/risk
assessment, a unique workshop with international representatives from
the fields of behavioral ecology, ecotoxicology, regulatory (eco)toxicology,
neurotoxicology, test standardization, and risk assessment resulted
in the formation of consensus perspectives and recommendations, which
promise to serve as a roadmap to advance interfaces among the basic
and translational sciences, and regulatory practices.
A field-based microcosm experiment was performed to investigate the effects of repeated pulses of the neonicotinoid insecticide imidacloprid on a lentic benthos assemblage. This specific microcosm method was chosen because it allows for both testing of a wide range of organisms under natural conditions and as well as gaining insight into intraspecific and interspecific interactions. The macrozoobenthos that colonised the microcosms was exposed to three pulses each 1 week apart at nominal concentrations ranging from 0.6 to 40 μg/L. Imidacloprid underwent fast aqueous photolysis due to optimal sunlight conditions during the test phase (half-life = 28 ± 8 h [monitored for 21 days]). Nonetheless, decreased abundance and emergence of Ephemeroptera and decreased survival of chironomid species of the subfamilies Tanypodinae and Orthocladiinae were observed at time-weighted average concentrations of 2.3 μg/L. In contrast, the gastropod Radix sp. became dominant at high imidacloprid concentrations, probably due to decreased competition for food with sensitive species. The results of this study show that repeated short-term contamination of imidacloprid at low concentration levels may affect aquatic ecosystems even under optimal conditions for photodegradation. The microcosm approach, with its simple and field-relevant design, proved to be a useful tool for assessing the effects of imidacloprid contamination.
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