Marenzelleria viridis (Verrill, 1873) (Polychaeta), a new benthic species within European coastal waters - Some metabolic features

The polychaete Marenzelleria viridis (Verrill, 1873) is a recent invader of European brackish waters (North Sea and Baltic Sea). As a member of the coastal infaunal community, dwelling in permanent tubes, M. viridis is frequently subjected to extreme environmental conditions, such as periods with restricted oxygen availability. When exposed to experimental anoxia, M. viridis follows in general the metabolic pathways exploited by many marine invertebrates. However, some differences become obvious. In contrast to most polychaetes, M. viridis used phospho-L-arginine for short-term energy provision and octopine was found to be the only end-product of cytosolic glycolysis. Alanopine and strombine, which were also measured were only found in traces. This corresponds with the relatively high activity of the octopine dehydrogenase (18 U g(-1) wet wt.), whereas the activities of other known pyruvate oxidoreductases were clearly lower or almost zero. Remarkable differences in the mode of anaerobic energy production were not found in populations with different salinity regimes from the Baltic Sea (Darss-Zingst bodden chain, S 8 parts per thousand) and the North Sea (Ems estuary, S 15 parts per thousand). Although glycine concentrations were clearly higher in the North Sea population, strombine did not occur as end-product of anaerobic glycolysis. However, alanine was accumulated to a higher amount in the North Sea population, albeit the concentrations of alanine were nearly the same in both populations. Compared to other marine polychaetes, M. viridis (North Sea and Baltic) showed only a moderate resistance against anoxic conditions. The reasons appear to be the relatively low glycogen content and insufficient reduction of the energy demand, indicated by the strong decrease in the energy charge after 24 h (0.82 to 0.70). Furthermore, M. viridis switched much earlier to energy production via the 'propionate pathway' and propionate was first detected in the incubation medium three hours after onset of anoxia. However, in M. viridis anaerobic energy production started at a very low oxygen tension (critical p(o2) at about 2 kPa) which indicates a very efficient use of oxygen even at severe hypoxia. (C) 1997 Elsevier Science B.V.