Secondary production ofPrionospio caspersi (Annelida: Polychaeta: Spionidae)

The annual somatic production ofPrionospio caspersi Laubier was estimated, between July 1986 and 1987, at a sandy shallow-bottom station in the area facing the Po River Delta, Italy, where this species is one of the most abundant. Primary recruitment occurs in summer, and maturation of gametes the following spring. Body sizes were estimated from the surface area of the anterior end of worms, projected onto a monitor and recorded using a digitizer tablet. Measurements, to the tenth setiger, were correlated with total length, total body surface area and AFDW. The annual production was 8.06 g m^–2 yr^–1 (AFDW) and the production:biomass (P:B) ratio 4.09. The results are discussed in relation to some physical and chemical features of the environment, stressing differences with the life cycle of other coexisting populations.