around the Northeast Pacific Gyral. Sverdrui; (:.946, fig. 209A) , indicated that the 

 source of this water is at about 40'-^., 140°W. This results in a sub-surface re- 

 circulation over the area of water that is already low in inorganic phosphate. The 

 acceleration of the natural tendency for organic phosphate to settle out as partic- 

 ulate matter by the downward motion in the area of subsidence would also contribute 

 to the barrenness of the recirculating water. 



The only perceptible evidence that enough mixing to enrich the surface 

 layers is induced by the impingement of the west to northwesterly currents on the 

 islands was shown in the analyses of zooplankton abundance by King and Hida (1954). 

 They found that although the abundance of zooplankton was almost uniform throughout 

 the region, the upstream area to the south and east of the island of Hawaii yielded, 

 on the average, the lowest volumes (cruises 10 and 12, stations 26 to 30). A com- 

 parison of the plots of the abundance of zooplankton (King and Hida 1954, fig. 10) 

 with the lateral plots of geostrophic currents for cruises 10 and 12 (figs. 13 and 

 24) indicates that there were slight maxima at, or near, the cyclonic eddies in the 

 lee of the islands during both cruises and at station 3I during cruise 10. However, 

 two other maxima occurred that could not be attributed to, nor remotely connected 

 with, any unusual hydrographic features, the first at station 5 during cruise 10 

 and the second at station 6 during cruise 12. The first was particularly interest- 

 ing since it was 21 ml/l,000m3 higher than or 1.5 times that of any other station, 

 and it occurred at the same station as the inexplicable high inorganic phosphate 

 content in the upper 100 m. during cruise 12. 



The writer believes that the occurrence of the zooplankton maxima at or 

 near the centers of the cyclonic eddies and the frequent occurrence of high salin- 

 ities and low temperatures at their centers are the result of divergent motion 

 which causes some enrichment of the surface water. The slightness of the maxima 

 and the number of exceptions to the increase of salinity and decrease of tempera- 

 ture at the centers indicate that vertical motion is small and intermittent at best. 



Acknowledgements 



The data embodied in this report represent the combined efforts of a 

 large number of the staff of tOU. Hov«ever, special acknowledgement should be made 

 to M. B. Schaefer, cruise 1 field party chief, J. '£. King, cruise 10 field party 

 chief, H. J. Mann, cruise 12 field party chief, and to Mary Lynne Godfrey, who pro- 

 cessed or supervised the processing of most of the data. 



T. 3. Austin and G. R. Seckel made helpful suggestions and assisted 

 generously in the preparation of the final report. The figures were drawn by 

 Tamotsu Nakata. 



18 



