Combined effects of copper and food on the midge Chironomus riparius in whole-sediment bioassays

• Published in: Environmental pollution (1987) 2004, Vol.127 (1), p.99-107
• Main Authors: de Haas, Elske M., Léon Paumen, Miriam, Koelmans, Albert A., Kraak, Michiel H.S.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; benthic invertebrates; bioaccumulation; bioavailability; Biological and medical sciences; Biological Assay - methods; Chironomidae; Chironomidae - physiology; Chironomus riparius; Combined effects; contaminated sediments; Copper; Copper - toxicity; Eating; Ecosystem; ecosystems; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Environmental Monitoring - methods; Food; Fundamental and applied biological sciences. Psychology; Geologic Sediments; growth; lumbriculus-variegatus; organic-matter content; Sensitivity and Specificity; Soil Pollutants - toxicity; tentans; Toxicants; toxicity tests
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/S0269-7491(03)00252-5

Trophic state of an ecosystem may alter risk of sediment-bound toxicants to midges. Effects observed in whole-sediment bioassays must be seen as the joint effect of all sediment characteristics. In whole-sediment bioassays, however, adverse effects on test organisms are usually attributed to the presence of contaminants and effects of food are often ignored. The aim of this study was to analyze the response of the midge Chironomus riparius to sediment spiked with different combinations of food and copper. The responses of C. riparius to these spiked sediments were assessed in 10-day whole-sediment bioassays. Decreases in survival, dry weight, and length of C. riparius were observed with increasing copper concentrations. However, an increase in the amount of food resulted in an increase of larval dry weight and length until copper concentrations reached a critical threshold of 200 mg/kg. In addition, an increase in the amount of food resulted in a decrease of accumulated copper in the larvae. The present study demonstrated that the combination of copper and food in the sediment determines the performance of C. riparius in whole-sediment bioassays. The dependency of C. riparius on high feeding levels, which mask toxic effects, questions its suitability as a test organism for whole-sediment bioassays. Because benthic communities in polluted ecosystems are often exposed to varying levels of both food and toxicants it is concluded that the trophic state of the ecosystem may alter the ecological risk of sediment-bound toxicants to opportunistic benthic invertebrates such as C. riparius.