Adaptive responses of marine benthic invertebrates to hydrogen sulphide  <B>Adaptive responses of marine benthic invertebrates to hydrogen sulphide</B><P><B>Hans Theede</B><SUP>1</SUP><B>, Rolf Oeschger & Andreas Jahn</B><SUP>2</SUP><I><P> Universität Bremen, Fachbereich 2, Außenstelle, Bürgermeister-Smidt-Straße 20,<BR> D-27568 Bremerhaven, Germany</I><BR> 1,2. Present address: <I><BR> Institut für Meereskunde an der Universität Kiel, Düsternbrooker Weg 20, D-24105 Kiel, Germany</I><B><P> Abstract</B><BR> Reactions of marine macrofauna from sulphidic habitats to H2S and the mechanisms of detoxification of this toxic substance are reviewed on the basis of recent studies by our working group. Internal concentrations of this toxic substance may be kept low up to certain limits during exposure to environmental H2S. This is achieved by temporary exclusion, precipitation and/or by oxidation to non-toxic compounds, e.g. thiosulphate. In the low concentration range, part of the oxidation energy of the sulphide molecule may be used for the formation of ATP, as in <I>Heteromastus filiformis</I>. This phenomenon may also exist in more species than previously expected. During extended sulphide exposure an aerobic-based metabolism cannot be sustained. Species with high capacity for sulphide-induced anaerobiosis have good chances to survive. Anaerobic long-term survival is then correlated with strong reduction of metabolic rates. As long as the effects of H2S on metabolism are reversible, the recovery after the end of H2S exposure is accompanied by an increased recovery respiration. This is higher after anoxic H2S incubation than anoxic incubation alone. Different degrees of H2S resistance exist at the population level. Populations of <I>Macoma balthica</I> from the North Sea intertidal, from shallower depths of the western Baltic Sea, and from a sulphidic environment on the coast of the island of Hiddensee (southern Baltic Sea) were studied in this respect. The Hiddensee population exhibits best survival in H2S conditions. Genetic differences might be involved in the geographical differences of sulphide detoxification.<I><P> Keywords</I>: hydrogen sulphide, <I>Macoma</I>, <I>Heteromastus, Scrobicularia</I>, detoxification, cytochrome c oxidase, succinate, ATP formation.<P>