MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(HIL-1117-802329) Behavioural and biochemical effects of medetomidine on the three-spined stickleback (Gasterosteus aculeatus).

Hilvarsson, A¹, Lennquist, A², ¹ Dep. of Marine Ecology, Göteborg University, Fiskebäckskil, Sweden² Dep. of Zoology, Göteborg University, Göteborg, Sweden

ABSTRACT- Medetomidine is suggested as a new antifouling agent, and its effects on marine organisms are therefore being investigated. Effects on several species of fish have previously been found, including decreased oxygen consumption, alterations in activity of the enzyme CYP1A and decolouration due to melanophore aggregation. The aim of this study was to examine a broad range of effects and a wide concentration span to find the earliest and most relevant effects of medetomidine on the three-spined stickleback (Gasterosteus aculeatus). This is a well-studied species concerning both behavioural patterns and biochemical biomarkers, which makes it suitable as a test species. It is also wide spread in temperate areas and inhabits both fresh and marine shallow waters and harbours and may therefore be exposed to antifouling compounds. Marine living three-spined stickleback was collected on the Swedish west cost during reproductive season. Male fish were allowed to build a nest and set a territory in experimental aquaria, equipped with eelgrass and gravel, containing different concentrations of dexmedetomidine (0.1-500 nM). Their activity, appetite, aggression towards other males and courtship towards gravid females were studied. The female was removed after spawning and the male′s egg-guarding behaviour was studied for a period of time. Males were later sacrificed for determination of CYP1A (EROD) activity and DNA/RNA-ratio in a whole-body homogenate. These biomarkers were compared with the behavioural patterns in an attempt to find connections between them and to characterise the sub-lethal effects of medetomidine in this species. This investigation is one part of a broader hazard assessment within the evaluation programme of medetomidine.

Key words: medetomidine, behavioural ecotoxicology, biomarkers, three-spined stickleback