PRODUCTION, DYNAMICS AND DEMOGRAPHY OF AN AMPHIURA-FILIFORMIS POPULATION

Secondary production and population dynamics of the brittle star Amphi ura filiformis (O. F. Muller) were studied between June 1990 and Novem ber 1991 at 40 m depth in the Skagerrak, west Sweden. Mean abundance o f individuals > 1. mm in disc diameter was stable around 280 ind. m(-2 ) After a spawning maximum in June and July, settling post-larvae (ca 7000 ind. m(-2)) occurred in autumn 1991. Disc growth and gonad produc tion accounted for ca 68.9 % (1.8 g AFDW m(-2) yr(-1)) of the total an nual production in the population. About 13.3 % (0.34 g AFDW m(-2) yr( -1)) of the total production was allocated to regeneration of arms, pr obably a result of cropping by predators. Mean regenerated biomass in percent of total biomass for adult A. filiformis was between 12 and 30 % (mean 22 %). Annual production/biomass ratio was 0.46 yr(-1). The i nput of energy to arm regeneration indicates the importance of A. fili formis as an important food source.