120 .Marine Microbiology 



must not succumb to the temptation to describe Pavlova and 

 Ochrosphaera as physiologically transitional forms. 



Heterotrophic abilities need not be considered the sole cause 

 of the possible colonization or preference of some organisms for 

 organic-rich waters. Many organic substances are good trace- 

 metal solubilizers. Their beneficial action could be in making 

 available iron and manganese which are present mostly as par- 

 ticulates in seawater. Thus a non-heterotrophic photolithotrophic 

 organism incapable of utilizing particulate trace metals may bene- 

 fit. The colonization of the polluted waters of the Norwegian 

 fjords by Coccolithtis huxleyi, which is a photolithotroph prac- 

 tically devoid of heterotrophic abilities and with an apparent 

 low requirement for trace metals, cannot be ascribed to either 

 effect of organic solutes. Perhaps it grows tliere and in the 

 open sea because it resists pollution and can compete fa\'orably 

 in both environments with otiier species, either because the other 

 species may be more sensitive to pollution or because other vari- 

 ables, not considered in the present work like temperature, light 

 intensity, etc., may give Coccolithus the edge. 



While heterotrophy, vitamins, and trace-metal requirements 

 can be a primary cause of predominance of some organisms over 

 others, they should not be considered all-encompassing. Other 

 inti'insic physiological abilities, including di^ision rates of the 

 species and their versatility or response to other variables, and 

 their ability to produce or withstand the possible actions of 

 antibiotics of other species— all have to be explored to explain 

 predominance and succession of species. We should examine all 

 possible factors; or, to say it fashionably, let us view ecology 

 synoptically and holocoenotically, with due evaluation of relevant 

 interacting parameters. 



REFERENCES 



1. Aaronson, S., and Baker, H.: A comparative biochemical study of two 



species of Ochromonas. J. Protozoal., 6:282-284, 1959. 



2. Arnon, D. I.: Some functional aspects of inorganic micronutricnts in 



the metabolism of green plants, p. 351-383. In Buzzati-Traverso, 

 ed., Perspectives in Marine Biolop,tj. Univ. Calif. Press, 1958. 



3. Bernard, F., and Legal, J.: Plancton unicellulaire recolte dans I'ocean 



Indien par le Charcot (1950) et le Norsel (1955-56). Bitll. Int. 

 Oceonogr., Monaco. No. 1166, pp. 1-59, 1960. 



