

)70 .N16 



Figure 55. Plankton stations of the USS 

 NEREUS. 



The samples were collected with a Nansen net, 1.5 meters 

 long, constructed of No. and No. 8 bolting silk, and with a 

 40-centimeter mouth. In operation the net was lowered by 

 means of a weight and hauled in vertically while the ship 

 was hove to. South of the Aleutian Islands, most of the sam- 

 ples were taken in vertical hauls from a depth of 200 meters 

 to the surface. In the Bering Sea and northward, the hauls 

 were made from the bottom, usually at 40 to 60 meters, to 

 the surface. 



Figure 56 gives the relative volumes (measured by dis- 

 placement) of total plankton, adjusted for comparison to 

 60-meter hauls. Both zooplankton and phytoplankton are 

 included, hence the numbers represent total particulate 

 organic material screened from the water by means of this 

 type net. Usually the bulk, which in no case was large, was 

 made up of zooplankton, but at stations Nil, N14, and Nl6 the 

 bulk was primarily made up of diatoms. At stations Nil and 

 N14, Thalassiosira rotula, Thalassiosira nordenskioeldii , 

 Fragillaria striatula, and Nitzschia seriata were dominant; 

 at station Nl6 Fragillaria was overwhelmingly dominant. 



