ABSTRACT: Populations of the Baltic clam Macoma balthica show different degrees of sulphide tolerance in relation to sulphide contamination of their habitats. Specimens from sulphidic habitats such as the Gulf of Gda´nsk (Baltic Proper) and shallow waters near the island of Hiddensee (Southern Baltic Sea) have higher survival capacities during sulphide exposure than those from low sulphide contaminated environments such as Kiel Bight (Western Baltic Sea) and the Wadden Sea near Dorum-Neufeld (Weser estuary, North Sea). The tolerant clams are better able to protect cytochrome c oxidase against sulphide toxification. It can be assumed that this protection is due to slower sulphide diffusion into the tissues. Sulphide-tolerant specimens from highly sulphidic habitats have apparent sulphide diffusion coefficients which are roughly half those of sulphide-sensitive specimens from low sulphidic stations. Higher sulphide influx into the sensitive clams will negatively affect their metabolism, combined with longer inhibition of cytochrome c oxidase, resulting in higher mortality.

KEY WORDS: Macoma balthica · Population · Hydrogen sulphide · Apparent diffusion coefficient · Apparent detoxification constant · Cytochrome c oxidase · Macrofauna · Baltic Sea · North Sea

Published in MEPS Vol. 154 (1997) on July 31
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997