Marenzelleria cf. viridis (Polychaeta: Spionidae): ecophysiological adaptations to a life in the coastal waters of the Baltic Sea
Schiedek, D. (1997). Marenzelleria cf. viridis (Polychaeta: Spionidae): ecophysiological adaptations to a life in the coastal waters of the Baltic Sea. Aquat. Ecol. 31(2): 199-210. https://dx.doi.org/10.1023/A:1009907606161
Since its introduction into the Baltic Sea about ten years ago, the polychaete species Marenzelleria cf. viridis has spread rapidly. Meanwhile, this spionid settled in remarkable numbers predominantly in the coastal waters which provide some of the more variable and unstable habitats in terms of abiotic conditions. In the present paper, some of the underlying biochemical and physiological processes were experimentally examined which enables this polychaete to deal with several kinds of environmental stress such as variations in salinities, low oxygen concentrations and occurrence of hydrogen sulphide. The results obtained reveal that in the process of acclimation to different salinities free amino acids are involved, mainly alanine and glycine. The content of these amino acids were increased in worms acclimated to a higher salinity. When exposed to low ambient oxygen concentrations (severe hypoxia) M. cf. viridis started to produce energy anaerobically via pathways known from several other marine organisms. The presence of hydrogen sulphide in higher concentrations (1 mmol l-1) results in a more rapid production of succinate (indicator for anaerobic energy production via the succinate-propionate pathway) as compared to hypoxia alone, indicating a higher energy demand. Nevertheless, when exposed to enhanced ambient hydrogen sulphide concentrations (3 mmol l-1), M. cf. viridis is less affected by this toxic compound than other marine species, such as the related species Marenzelleria cf. wireni (North Sea). The field data indicate that the metabolic response obtained under experimental conditions is also important in the worm's natural habitat. Although the extent of anaerobic metabolites produced as well as the amount of thiosulphate (main sulphide detoxification product) was lower in the field as compared to the experiments, M. cf. viridis very likely has to face hypoxia and hydrogen sulphide in higher concentrations in its natural habitat.
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