Structural Changes in a Macrozoobenthos Assemblage After Imidacloprid Pulses in Aquatic Field-Based Microcosms

• Published in: Archives of environmental contamination and toxicology Vol. 65; no. 4; pp. 683 - 692
• Main Authors: Colombo, Valentina, Mohr, Silvia, Berghahn, Rüdiger, Pettigrove, Vincent J.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.11.2013; Springer; Springer Nature B.V
• Subjects: Analysis; Animal, plant and microbial ecology; Animals; Applied ecology; Aquatic ecosystems; Benthos; Biodiversity; Biological and medical sciences; Chironomidae; Contamination; Earth and Environmental Science; Ecosystem; Ecotoxicology; Ecotoxicology, biological effects of pollution; Emergence; Environment; Environmental Chemistry; Environmental Health; Environmental impact; Experiments; Fundamental and applied biological sciences. Psychology; General aspects; Imidacloprid; Imidazoles - toxicity; Insecticides; Insecticides - toxicity; Invertebrates - classification; Invertebrates - growth & development; Investigations; Laboratories; Low concentrations; Marine ecology; Microcosms; Microorganisms; Monitoring/Environmental Analysis; Neonicotinoids; Nitro Compounds - toxicity; Optimization; Pesticides; Photodegradation; Photolysis; Pollution; Soil Science & Conservation; Studies; Sunlight; Toxicity; Water Pollutants, Chemical - toxicity; Imidacloprid Concentration; Nominal Concentration; Imidacloprid; Sublethal Effect; Macroinvertebrate Assemblage; Nitro compound; Neonicotinoid; Pollution; Insecticide; Pesticides; Microcosm; Guanidines; Systemic; Community
• ISSN: 0090-4341; 1432-0703
• DOI: 10.1007/s00244-013-9940-2

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.