On the ecophysiology of the sponge Halichondria panicea in Kiel Bight. II. Biomass, production, energy budget and integration in environmental processes

Abstract

Between December 1983 and April 1985 field experiments and laboratory observations on Halichondria panicea were performed In the Hausgarten area at Boknis Eck, Kiel Bight The sponge population was sampled regularly by dredging and scuba diving Field growth experiments were conducted at the same time Phyllophora sp and Phycodrys sp were the preferred substrate algae while Delesseria sanguinea and fllamentous fine algae served as substrate only occasionally. A variety of inorganic and organic hard substrates was also found to be accepted by sponges. Growth of H panicea was observed between March and July. Growth rates seemed strongly dependent on temperature, less correlated wlth food avallability The most vigorous growth occurred in May and June After July a strong decline In mean weighto of the individually marked specimens resulted in negative growth rates until the end of September During late fall and winter no changes in mean individual weight were observed Considerable changes in biochemical composition (condition index and protein lipid and glycogen content) and appearance of young colonies of H panicea in early fall indicate that the main reproductive actlvity occurs In August and September As this is the time of greatest weight loss in adults, it can be inferred that adult H. panicea degenerate and dissintegrate after reproduction.