|
2K - Sediment Assays (TUP/155) Sediment-water Chironomid toxicity test using spiked sediment with internal food source − a more realistic test? Gildemeister, Thomas, Nagel, Roland, ABSTRACT- Sediments can be a sink for chemicals which have a tendency to adsorb or bind covalent to particulate matter. Contaminants with high hydrophobicity can reach high levels in sediments. Effects on benthic organisms have consequences on nutrient recycling, because the sediment plays an important role as habitat and in the mineralisation of detritus. The OECD 218 sediment-water Chironomid toxicity test using spiked sediment describes a test system to assess the effects of prolonged exposure of chemicals to the sediment-dwelling larvae of the freshwater midge Chironomus sp. We think this guideline is questionable, because external feeding using uncontaminated food is recommended. Addition of uncontaminated food during the test may mask toxic effects of the contaminated test sediment. Therefore a new test system without external feeding of the larvae of Chironomus riparius is presented. Alder and nettle leaves occuring in natural sediments are used as internal food source. 3,4-DCA known for its covalent binding to sediment and TBT with an endocrine disrupting potential was investigated in an CEFI-LRI project. A wide concentration range covering natural concentrations was applied. Sex ratio, rate of emergence and EMT50 (time at which 50% of the test organisms had emerged) were the population relevant ecotoxicological endpoints. Key words: Chironomus riparius, sediment toxicity testing |
