ABSTRACT: The ostracod Cyprideis torosa, Jones 1850 is one of the most abundant species of benthic fauna in the shallow water areas of the Baltic Sea, even in sulphidic habitats. Investigations of the physiological basis of the high resistance to hypoxia and hydrogen sulphide show that the ostracod is indeed able to oxidize penetrating sulphide to non-toxic thiosulphate and sulphite and to eliminate the oxidation products rather quickly. This detoxification, however, is not effective enough to prevent an increase of sulphide in the ostracod's body. In spite of valve closure and consequently a low apparent diffusion coefficient of about 8 x10^-7 cm² s^-1, sulphide concentration in the tissues increases rapidly. Ambient sulphide concentration (1 mM sulphide) was reached within 2 h, due to the small size of the ostracod. High succinate values in the tissues during sulphide exposure indicate that C. torosa is able to switch over to anaerobiosis, even under oxic conditions (70% air saturation). Obviously, C. torosa can resist long-term sulphidic conditions due to its high capacity for long-term anaerobiosis.

KEY WORDS: Cyprideis torosa · Hydrogen sulphide · Diffusion · Anaerobiosis

Published in MEPS Vol. 142 (1996) on October 24
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996