ABSTRACT
Because of the complexity of marine food webs, and the major dissipation of energy at each step of the food chain, the empirical model proposed by Steele (1965, 1974) for the North Sea and shown in Fig. 1 indicates that out of 100 g Cm-2 yr-1 produced at the sea surface as net primary production by the phytoplankton, only 0.3 g Cm-2 yr-1 appears as yield to man through the pelagic food web, and approximately 0.13 g Cm-2 yr-1 from demersal fish. Despite the huge dissipation of materials that occurs at each step in the food web, however, sufficient carbon evidently flows through the detrital food web, even in planktonbased ecosystems such as the North Sea, for as much as 30% of total fish production to be dependent on conversion through the community which lives on the sea bed.
