-100- 



Another important ecosystem feature (not considered in 

 these diagramatical representations) concerns the amount of 

 energy leaving the system. Energy in the form of biomass is 

 removed by the northward migration of whales and fish (e.g., 

 great whales and Patagonian hake) . Increased commercial 

 exploitation of living resources will also remove energy 

 from the ecosystem. In natural systems, net energy losses 

 may be relatively insignificant either because metabolic 

 products return energy to the system or long migrations out 

 of the system are limited. 



On the other hand, large-scale, commercial harvesting 

 of krill, fish, and squid would permanently remove these 

 system components thereby altering energy available to the 

 ecosystem. One cannot accurately predict the repercussions 

 of such activities. 



The role of organisms in nutrient cycling must also be 

 considered (Herbert and Bell, 1974). Nutrients enter the 

 ecosystem in a variety of ways, probably one of the most 

 important being the nutrient rich Warm Deep Layer which 

 moves south and upwells near the coast. Phytoplankton 

 assimilate these nutrients and are then consumed by krill 

 and other zooplankton. In their diurnal migrations, krill 

 distribute nutrients through the upper water column and 

 therefore may be important in recycling these substances 

 (Mauchline and Fisher, 1969). The nutrients released in 

 their feces are in turn taken up by copepods , bacteria, and 

 other organisms -- the net effect being the recruitment and 

 maintenance of richer nutrient concentrations in upper water 

 levels. Moreover, both Marr (1962) and Clowes (1938) felt 

 that krill gut activity was important in creating silicate 

 concentrations in Antarctic waters. Clarke (1977) suggested 

 that, similar to krill, diurnal squid migrations may redistribute 

 nutrients. The consequences of a krill and/or squid harvest 

 on nutrient recycling within the Antarctic marine ecosystem 

 is unknown. 



