Bacterial Habitats in the Antarctic Em'ironmcnt 



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ROLE OF ALGAL VOLATILE ACIDS IN THE NUTRITION 

 AND INHIBITION OF PLANKTONIC MARINE BACTERIA 



The sparsity of bacteria in the euphotic zone of Antarctic 

 marine waters, which are usually highly productive in phyto- 

 plankton, has been noted by the earlier Antarctic expeditions 

 as well as by Lebedeva (9) and Kriss et al. (7), and in the ob- 

 servations made earlier in this paper. The finding that certain 

 phytoplankton blooms contain an antibacterial acid suggests that 

 the well recognized bactericidal property of sea water reviewed 

 by Carlucci and Pramer (6), may be due to substances of biologi- 

 cal origin (12, 13). However these "ectocrines" (10) have been 

 poorly defined and many phenomena such as the dominance and 

 succession of algal blooms have been ascribed to such substances 

 without adequate substantiation. 



An immediate objection to attributing the sparsity of marine 

 bacteria in Antarctic waters to the high acrylic acid content (8% 

 dry weight) of the Phaeocystis blooms (21) is that an acidic 



