36 Marine Microbiology 



marine enxironmeiit is not so clear, although Ritchie has shown 

 that Zalerion at least has an osmotic reaction to the NaCl content 

 of tlie medium and to temperature. 



There are in the sea a number of parasitic Phycomycetes. 

 Myers (Chapter 31) has listed a number of algal species para- 

 sitized by Ascomycetes, while some of the estuarine and neritic 

 sea grasses are also attacked. Algae washed ashore are rapidly 

 attacked by autochthonous fungi. 



A great deal of work on the rotting of wood and cordage has 

 been recorded by Meyers, Kohlmeyer, Hohnk and others. While 

 this is important from a commercial point of view, and necessary 

 to give a true picture of estuarine phenomena, it has tended to 

 divert attention from studies of the role of fungi in the open 

 ocean. There seems to be little or no evidence of the role of 

 fungi in the destruction of phytoplankton or zooplankton, though 

 it may well be that chitinoclastic fungi are important in the 

 destruction of skeletons of copepods, euphausids and other plank- 

 tonic Crustacea. Because of the lack of lignin and lignocellulose 

 in the open sea, fungi attacking these materials would not be 

 expected there. 



Yeasts, on the other hand, appear to be widely distributed, 

 (although in small numbers) even in the open ocean, and have 

 been recorded incidentally by several authors from fish, sea water, 

 estuarine muds etc. Fell and van Uden (Chapter 32) have 

 studied in more detail yeasts from Biscayne Bay, from subtropical 

 areas on the Atlantic coast of the United States and from the Cali- 

 fomian coast. They conclude that the majority of these yeasts are 

 physiologically similar to their terrestrial counterparts, but that 

 there are species of Rhodotorula and Candida that may be truly 

 marine. These are important considerations and suggest that a 

 wider study of the yeasts to be found in marine environments 

 may be profitable. 



VIRUSES IN THE SEA 



The existence of viruses in the sea has been the subject of 

 speculation since the demonstiation of bacteriophage by d'Her- 

 elle. However, it is only recently that we have been able to 

 assess the likelihood and importance of viruses in marine en- 

 vironments. Phages active against human intestinal bacteria have 



