Figure 6.

The basic structure of the Southern Ocean food web. Note that the fundamental topology is branched, with carbon fixed by primary producers being used by three principal and competing pathways (to zooplankton consumers, the microbial network and the benthos). The arrows show only the major routes for energy flow, with the size indicating the dominant pathways for the western Antarctic Peninsula (WAP) oceanic food web over the continental shelf in summer, based on the inverse modelling results of Ducklow et al. (2006). The major route for energy flow is from phytoplankton to zooplankton consumers (and predominantly Antarctic krill) and thereby to higher predators, with secondary pathways to the microbial network both directly from the primary producers and also from zooplankton via the detrital pathway. In the WAP area, flux to copepods and salps in the zooplankton, or directly to the benthos, are important but secondary. Note that in other areas of the Antarctic, and possibly at other times in the WAP area, the relative importance of the major pathways will be different. Modified from Clarke & Harris (2003).