Toxicity and neurotoxicity profiling of contaminated sediments from Gulf of Bothnia (Sweden): a multi-endpoint assay with Zebrafish embryos

Abstract

Background: The toxicological characterization of sediments is an essential task to monitor the quality of aquatic environments. Many hazardous pollutants may accumulate in sediments and pose a risk to the aquatic community. The present study provides an attempt to integrate a diagnostic whole mixture assessment workflow based on a slightly modified Danio rerio embryo acute toxicity test with chemical characterization. Danio rerio embryos were directly exposed to sieved sediment (≤ 63 μm) for 96 h. Sediment samples were collected from three polluted sites (Kramfors, Sundsvall and Örnsköldsvik) in the Gulf of Bothnia (Sweden) which are characterized by a long history of pulp and paper industry impact. Effect data were supported by chemical analyses of 237 organic pollutants and 30 trace elements. Results: The results show that malformations and neurotoxic compounds are the main drivers of differentiation in chemical and effects analyses, respectively. Specific spinal cord malformations and delayed hatching were observed only in sediments from Kramfors while light hyperactivity was seen only after exposure to sediments from Sundsvall. Conclusions: Our experiments demonstrate that specific chemical profiles lead to specific effect patterns in Danio rerio embryos. In fact, behavioral endpoints could help detect the exposure to neurotoxins, and the observation of body malformations seems to be a potential tool for the identification of site-specific pollutants as polychlorinated biphenyl (PCBs), brominated flame retardants (BFRs) and several pesticides. Overall, results show the suitability of Danio rerio embryos for the fast screening of sediment samples.