In situ and laboratory sediment toxicity testing with ceriodaphnia dubia

Abstract

AbstractEcological assessments of sites containing hazardous wastes are improved by field testing. In situ exposures of Ceriodaphnia dubia were conducted in a stream impacted by several effluents, a combined sewer overflow and a creosote treatment operation. Sediments contained high levels of metals and polynuclear aromatic hydrocarbons. Fish and macroinvertebrate community indices were depressed. Ceriodaphnia dubia were placed in sediment exposure chambers in the stream for 48 h and also exposed to sediments that were simultaneously collected in the laboratory. Percent survival was generally higher in situ as compared to static laboratory exposures; however, overlying water toxicity was lower in laboratory assays. Average survival rates in elutriate fractions were slightly higher than interstitial or solid‐phase exposures, and filtration reduced both elutriate and interstitial fraction toxicity. In situ sediment exposures proved to be sensitive indicators of both degraded and nondegraded stream conditions. Results show traditional sample collection and laboratory toxicity test methods may alter the water and sediment toxicity that occurs in situ. This highlights the importance of laboratory validation and in situ testing in aquatic safety assessments.