Energy Flow in the Southern Ocean Food Web

Summary

Current knowledge of energy flow within the Southern Ocean food web is reviewed in the light of 6 recommendations for future work made by Knox (1970). The most recent estimate of total annual open ocean primary productivity is about 6,400 times 10⁶ t, but the contribution from ice-associated algae is not known. Almost nothing is known about the quantitative importance of bacteria or the heterotrophic micro-zooplankton, although the few observations available suggest that the importance of this loop in the food web is likely to be as great as in other oceans. Knowledge of energy flow between the Antarctic Krill, Euphausia superba, and the higher predators is better, but by no means complete. Little is known about the role of dissolved or particulate organic carbon, or of fluxes to the benthic community, although many of the life-history features of the shallow water benthos indicate that this flux is important. Recent physiological and year-round autecological studies of benthic species indicate that winter metabolic rates are very low, and hence there is no need for the large lipid stores so characteristic of the plankton, and suggest that growth efficiencies are high and turnover rates low.