To determine the variations in zooplankton abundance related 

 to distance from land^ differences between inshore and offshore areas, 

 or between the windward and leeward sides of these oceanic islands 

 would require a very detailed and elaborate studyo An opportunity to 

 obtain a small amount of information on these problems was afforded by 

 cruise 9 of the Manning o Paired hauls were made at a series of 5 sta- 

 tions (figo 2s part B) extending from about ^ mile from the beach—the 

 closest the vessel could approach— to 5 miles offshoreo Two such 

 sections were occupied, one starting in Kaneohe Bay on the windward 

 side of Oahu and extending offshore and the other extending offshore 

 from Waianae, on the leevrard side of Oahu. Unfortunate ly^ however, 

 the Kaneohe series was taken during daylight hours and the Waianae 

 series at nighto Also, because of insufficient depth, the standard 

 200-meter oblique haul could not be employed ax- all stations o A 

 stair-stepped haul from the bottom to the surface was carried out at 

 the inshore stations where the depth was less than 200 meters „ Despite 

 these unavoidable sources of variation, rather consistent results were 

 obtained at the two locations (figo 13),, On both series the greatest 

 plankton volumes vfsre secured at the 2-mile stationi volumes decreased 

 to a moderate degree in both inshore and offshore directions o Treat- 

 ing the data with an analysis of variance (table 10) revealed signi- 

 ficant differences (P <0o05) betvreen the two localities, Kaneohe and 

 ?feianae, and also significant differences (P < 0o05) among stations© 

 The interaction was not significant, thus indicating parallel varia- 

 tions for the two localities » Viie believe the differences betvireen 

 localities to be related primarily to the time of hauling and the 

 associated diurnal variation in plankton abundance o An adjustment of 

 the 200-meter hauls according to the usual procedure appeared to elim- 

 inate the day-night difference (table 22) » Ihe significant variation 

 among stations may be real and related to basic differences in pro- 

 ductivity or possibly to differences in the hauling methode No definite 

 conclusions, however, can be drawn from these few observations « 



CORRELATIONS WITH ENVIRONMENTAL FACTORS 



The available hydrographic data demonstrate that the Hawaiian 

 waters comprise a relatively homogeneous environment characterized by 

 slight geographical variations in physical and chemical factors o Our 

 plankton sampling indicated correspondingly uniform conditions of 

 zooplankton abundance throughout the islands (figo 10), Nevertheless, 

 the authors thought it worthwhile to determine the degree of correla- 

 tion of zooplankton catch and certain environmental factors considered 

 most likely to have biological si ginificanceo 



Surface and subsurface temperatures obtained by means of a 

 bathythermograph were available for all seven cruises covered in this 

 report o Three of the cruises--10, 12, and 17 of -Uie Smith --were com- 

 bined hydrographic and plankton cruises and furnished additional 

 measurements of the environmento Inorganic phosphate analyses were 



36 



