EFFECTS OF MERCURY ON THE VENTILATION BEHAVIOR OF THE POLYCHAETE NEREIS-VIRENS (SARS)

The behavioural response (i.e. ventilation rate, duration of ventilati on bursts and length of pauses between ventilation bursts) of Nereis v irens (Sars) from mercury polluted sediment (close to the Cheminova ch emical plant) in the western part of the Limfjord, Denmark, was compar ed with the response of non-exposed populations from the eastern part of the Limfjord. Individuals from the non-exposed site reacted strongl y to 30 ppb Hg by increasing their ventilation rate. At higher Hg conc entration ventilation rates decreased and at 3000 ppb it almost ceased . Worms from the same site pre-acclimated to 50 ppb Hg did not react a t the 30 ppb level. Ventilation rates of these worms increased when ex posed to 300 ppb and decreased at 3000 ppb. Individuals from the Chemi nova site pre-acclimated in Hg-free water did not react at the 30 ppb level and showed only low responses at 300 and 3000 ppb. Durations of ventilation bursts and rest periods decreased during Hg exposure, No s ignificant ventilation response of worms from the Cheminova site was e vident at any Hg exposure when pre-acclimated to 50 ppb Hg in the labo ratory. The present results show that the ventilation response of N. v irens to Hg is an excellent behavioural biomarker of acute Hg stress.