Chapter 24 



The Relative Importance of Groups of 



Protozoa and Algae in Marine 



Environments of the Southwest Pacific 



and East Indian Oceans 



E. J. Ferguson Wood 



Xhis paper is a report of current work, so the conclusions will 

 be speculative rather than positive. Studies have been made of 

 living phytoplankton in the Coral and Tasman Seas to the east of 

 Austialia, in the North-east Indian Ocean, and the seas among 

 the islands of Indonesia, including the Arafura Sea. These 

 studies, especially in the Indian Ocean, will be extended in the 

 near future, particularly in association with the oceanographic 

 program of SCOR. 



Examination of the living phytoplankton at sea has high- 

 lighted the following points: the varied ratio between the so- 

 called net-phytoplankton (diatoms, dinoflagellates etc.) and the 

 nannoplankton (smaller forms which usually escape the finest 

 nets that can be used ) ; the frequent occurrence of large numbers 

 of colorless flagellates, the large numbers of small, naked dino- 

 flagellates, the importance of the Myxophyceae in tropical waters 

 in these regions and the increase of the ratio of diatoms to dino- 

 flagellates closer inshore and in cooler waters. 



RATIOS OF NET PHYTOPLANKTON TO NANNOPLANKTON 



The substitution of containing samplers for nets in catching 

 phytoplankton has demonstrated the importance in the oceans 

 of phytoplankters ranging in size down to 1 micron, and these 

 smaller forms are known as nannoplankton, ultraplankton, etc. 

 The division between these small elements and the larger ones 

 that were usually caught in nets with a mesh size between 150 and 



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