C-1 



INTRODUCTION 



Reviews of zoogeography of the southern ocean iden- 

 tify the Antarctic Convergence as the northern boundary of 

 the Antarctic Zone (Broch, 1961; Knox, 1968; Hedgoeth , 

 1969, 1970). Waters north of the Convergence are in the 

 Subantarctic region. Some species of phytoplankton such 

 as chaetoceros flexuosus Mangin or fragi lariops is sub linear is 

 (van Heurck) Heiden are only found in the Antarctic zone 

 (Hasle, 1968). The krill Euphausia superba are only found 

 south of the Convergence (Marr, 1962). Antarctic seals 

 and penguins probably do not migrate across the Convergence. 

 Some fish and most whales do cross the Convergence to feed 

 in the Antarctic every year. The Antarctic marine ecosys- 

 tem is defined biologically by the species found in the 

 Antarctic zone. 



The Antarctic marine ecosystem is also defined by 

 physical oceanographic conditions which strongly affect 

 its biology. The Antarctic Convergence is a physical fea- 

 ture. Seasonal changes in available light and extent of 

 ice cover are characteristic of the Antarctic zone. The 

 Circumpolar Current serves to connect waters south of the 

 Convergence into a single system through transport of 

 nutrients and plankton. 



