SEASONAL VARIABILITY IN BIOCHEMICAL-COMPOSITION OF THE POLYCHAETE NEREIS-VIRENS (SARS) IN 2 TIDAL FLATS WITH DIFFERENT GEOGRAPHIC ORIENTATIONS

Marine invertebrates on a tidal flat are submitted to dramatic changes of their habitat associated with the tidal cycle. Information about s easonal variability in the biochemical composition as a function of th eir geographic situation on the tidal flat are sparse in nereid polych aetes. We demonstrate that biochemical composition of Nereis virens va ries accordingly to the weight and the altimetric level on the tidal f lat. Glycogen, proteins, lipids and total sugars in N. virens increase d at the lower tidal level in the north-east oriented bay. At the uppe rmost part, we have found younger and rather small individuals. In the south-west oriented tidal flat, spatial distribution patterns were le ss evident. However, glycogen content was 3-fold higher in N. virens o f the second tidal flat. These results show that biochemical compositi on of N. virens is not completely dependent upon the size of the worm but follows a seasonal trend particularly at the lower level of the tw o bays. Our results indicate that favourable nutritional conditions fo r growth are prevailing in these sites and that these monotelic anneli ds were possibly not in their reproductive state.