BEHAVIORAL-RESPONSES OF NEREIS-DIVERSICOL OR (MULLER,O.F.) AND NEREIS-VIRENS (SARS) (POLYCHAETA) TO FOOD STIMULI - USE OF SPECIFIC ORGANIC-MATTER (ALGAE AND HALOPHYTES)

Plant preference and feeding selectivity were studied in juveniles of Nereis diversicolor O.F. Muller) and Nereis virens (Sars) (Polychaeta: Nereidae) to evaluate the potential role of these species in the inte gration and transfer of vegetal debris to the littoral ecosystem. Resu lts show that these annelids ingest the main plant species (algae and halophytes) that are abundant in the marshes of the bay of Mont-Saint- Michel (France) and (or) the A l'Orignal Inlet (St. Lawrence Estuary, Canada), independently of their origin or level of decomposition. Juve niles select detritus on the sediment surface (feeding area) and accum ulate them in their burrow. Constant irrigation by young individuals ( approximate to 35% of time budget) maintains aerobic conditions favour ing the decay process of plant debris by stimulating bacterial growth (gardening). Our results suggest that individuals of both N. diversico lor and N. virens play an important role in the transfer and integrati on processes and the residence time of vegetal detritus of the interti dal ecosystem.