Abstract
The metabolic strategies of the polychaete Marenzelleria viridis (Verrill 1873), a successful immigrant into Baltic shallow eutrophic coastal waters with meso-to oligohaline salinities since the 1980's, were determined by simultaneous calorimetry and respirometry. Resistance to oxygen deficiency under varying ecological conditions was also examined. The results of the studies with this immigrant were compared to those with the common indigeneous polychaete Nereis (Hediste) diversicolor (O.F. Muller). At 10 and 20 °C and the average habitat salinity of 5‰ M. viridis gradually reduced its metabolic activity with declining oxygen partial preessures (pO2), whereas H. diversicolor maintained its metabolic activity. The metabolism of both species remained fully aerobic down to a pO2 of 2 kPa. An additional hyposmotic stress of 0.5‰ salinity at a temperature of 20 °C led to a decrease in the rate of oxygen consumption in H. diversicolor below a pO2 of 10 kPa, whereas metabolic heat dissipation remained constant. M. viridis, however, further reduced both, metabolic heat dissipation and oxygen consumption. The metabolic rates of both species under anoxia were similar, amounting to ca. 20% of the normoxic rate. The resistance of the two species to oxygen deficiency was also similar, ranging between 21 and 290 h (median survival time LT50), depending on temperature and salinity. Specimens used in the present study were collected from the Southern Baltic coastal inlet of “Dars-Zingster-Boddenkette” during 1992 and 1993.
Published Version
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