Integrating biochemical and growth responses in ecotoxicological assays with copepods

• Main Author: Dahl, Ulrika
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM) 2008
• Subjects: Environmental toxicology; Miljötoxikologi; Calanus finmarchicus; Copepods
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8218

The understanding of effects of chemical exposure in nature is lagging behind. Predictions of harmful effects of chemicals on aquatic organisms rely mainly on ecotoxicity tests. To improve the understanding of the biological linkage between the cellular and organismal responses to a chemical in an ecotoxicological test, the major aim of this doctoral thesis was to investigate the usefulness of two biochemical endpoints, contents of RNA and ecdysteroids, by incorporating them with life-history traits of copepods (Crustacea). To do so, the two methods needed to be established at our laboratory. Both biochemical methods are more commonly used in basic biological research, but I here present its usefulness in ecotoxicological testing. It was found that individual RNA content as a biochemical endpoint was significantly altered in the brackish water harpacticoid copepod Nitocra spinipes when exposed to the pesticide Lindane (paper IV) and low concentrations (0.16<g . L-1) of the pharmaceutical Simvastatin (paper I) during partial life cycle tests. However, the RNA content was insensitive as endpoint in the fresh water harpacticoid Attheyella crassa during multigenerational exposure (2 – 3 generations) to naturally contaminated sediments (paper III). The second biochemical endpoint, ecdysteroid content (a crustacean growth-hormone), was shown to be a useful tool for ecotoxicological studies using N. spinipes (paper IV), as well as for increasing the understanding of lipid turnover and reproduction of the marine calanoid copepod Calanus finmarchicus (paper V). In paper I and IV, I present a balanced ecotoxicological test, useful for substances with suspected developmental disruptive effects. In this type of test, a balance between test adequacy, exposure time, and costs has been proven useful. Further, the reliability of tests (paper II) with N. spinipes was increased by optimizing its food regime. In paper II, 25 different combinations of micro-algae were tested during short- and long time exposure, and a suitable ...