PARENT SESSION

2C - Biomarkers
Poster Hall
8:30 AM - Tuesday, 29 April 2003
Chair: Hansen, P.D.¹, ¹
Co-chair: Vindimian, E.², ²

(TUP/107) Avoidance behaviour in terrestrial isopods (Crustacea) as an indicator of metal exposure.

ZIDAR, PRIMOZ¹, KERO, ANDREJA ¹, KASCHL, ULF², ŠTRUS, JASNA¹, BOZIC, JANKO ¹, ¹ UNIVERSITY OF LJUBLJANA, LJUBLJANA, SLOVENIA, SLOVENIA² UNIVERSITY OF HEIDELBERG, HEIDELBERG, GERMANY, GERMANY

ABSTRACT- Behavioural responses to pollutants represent a higher organizational level of biomarkers. It is the final integrated result of a diversity of biochemical and physiological processes. In terrestrial isopods feeding is the main route of contaminant intake. In view of this, behaviour avoidance of metal contaminated food by terrestrial isopods was investigated. We performed several paired food choice experiments with Porcellio scaber and Oniscus asellus where Cd-dosed food (20, 45, 200 and 450 mg/kg dry weight) was offered together with untreated food for three weeks. After each week food consumption rate and metal accumulation were analysed and compared in relation to water-soluble and total cadmium concentrations in food. Investigations were supported by computer-aided video tracking where number of animals' visits and time spent near clean and Cd-dosed food were followed for 48 hours. P. scaber as well as O. asellus discriminated against Cd-dosed food. Preference for uncontaminated food was significant at all cadmium concentrations used. In P. scaber uncontaminated food preference rose with time of exposure and cadmium concentration in food. Still, the maximal preference ratio was 65% (untreated food): 35% (Cd-dosed food). Consequently, cadmium body burden increased with time of exposure and cadmium concentration in food consumed. Data from video tracking experiments revealed that animals visited Cd-dosed food as often as untreated food but they spent much less time near Cd-dosed food, irrespective of cadmium concentration. This means that animals are attracted to Cd-dosed food as well, but they probably stop feeding prematurely. Avoidance of Cd-dosed food is a behavioural response, most likely induced by adverse metabolic effects of ingested cadmium. Animals in polluted environment consequently spend more energy in searching for less contaminated food as well as for metals detoxification. Avoidance behaviour in terrestrial isopods is therefore directly related to growth and survival.

Key words: cadmium, woodlice, food preference, video tracking