POPULATION-DYNAMICS, PRODUCTIVITY AND ENERGETICS OF THE LUGWORM ARENICOLA-MARINA (ANNELIDA, POLYCHAETA)

Dispersion, abundance dynamics, size-frequency, mortality, growth, biomass, productivity, energy flow, germ-cell development, sex ratio, breeding season, natality and fertility of Arenicola marina were investigated from 1975 to 1977 at four intertidal study areas near Roscoff (Brittany, France). Numerical abundance is highest in the upper shore. Here the population consists chiefly of small immature worms. Towards the lower shore, abundance decreases whereas individual size increases. Annual variations in abundance are greatest in the upper shore. Variation in abundance is essentially influenced by wave movement. There is evidence supporting the view that, in spring, small lugworms migrate from the upper part of the shore all over the tidal flat area. Growth rates vary significantly within the areas examined. Generally they increase with increasing duration of submersion. A. marina is the most important producer among the polychaetes so far examined. Productivity is highest in sheltered flats and decreases with increasing disturbance by water movement. Energy budgets of lugworms are estimated. Energy requirements and energy supply are discussed, particularly the extent to which filtration in the headshaft of the burrow may cover food requirements. A brief description of gametogenesis is given. In 1975 at Penpoul the breeding season began in October and lasted two months. At the other study areas- Le Pouldu, Le Guillec and Le Dossen - spawning began in October and lasted one month. In 1976 spawning began earlier but terminated at the same time as in 1975. © 1979 Biologischen Anstalt Helgoland.