APPENDIX A 



ZOOPLANKTON DISTRIBUTION ABOUT AN OCEANIC ISLAND 



Palmyra Island lies 352 nautical miles north of 

 the Equator and about a thousand miles south of 

 Honolulu. In relation to other islands of the 

 Line Islands group, Palmyra is located about 33 

 miles southeast of Kingman Reef and 120 miles 

 northwest of Washington Island. The island is 

 an atoll consisting of 40 to 50 small islets arranged 

 in a rectangle about 4 miles long and IK miles 

 wide. The islets rest on a shallow reef platform 

 6 miles long and 2 miles wide with the long axis of 

 the platform extending in an east-west direction. 

 Outside the 10-fathom line the submarine slope is 

 steep, ranging from 2,500 to 3,000 feet to the mile 

 and descending to the general depth of about 

 15,000 feet (Wentworth 1931). 



Occupying latitudes 5°52' N. to 5°54' N. at 

 approximately 162° W. longitude. Palmyra lies 

 close to the soutliern boundary of the Counter- 

 current and ordinarily is batlied by it throughout 

 the year. The surface current was flowing to the 

 east at the time of our observations, as was to be 

 expected, since, in the region of the Line Islands, 

 the southern boundary of the Countercurrent has 

 alwaj's occurred south of 5)2° N. latitude on the 

 numerous crossings of POFI vessels. 



The zooplankton abundance about the island 

 was investigated in January 1953, on Hugh Af. 

 Smith cruise 19, by running lines of stations out 

 to the north, south, east, and west, starting as 

 close to the reef as the vessel's safety permitted 

 and extending out to a maximum of about 14 

 miles (fig. 3). A total of 20 hauls were made, 

 all at night. With the exception of a single haul 

 made on the shallow shelf west of the island which 

 yielded a sample about twice the average volume 

 of the 200-meter oblique tows, the results indicated 



■' The salinity and temperature data collected on this cruise indicated that 

 the waters about Palmyra were also rather uniform as to chemical and phys- 

 ical conditioDs; e. g., the maximum variation in surface temperature was 

 less than 0.5° C. 



388 



a rather uniform distribution of zooplankton 

 throughout the island waters." From an analysis 

 of variance we conclude that the difTerences 

 between the four series of stations were not signifi- 

 cant (F = 0.896, P>0.05). There was a slight 

 indication of an inverse relation between the 

 zooplankton catch and distance from land (fig. 22) ; 

 a regression analysis showed, however, that this 

 trend was not significantly different (b=— 0.431, 

 P>0.1) from a random distribution. 



The variation about Palmyra was less than we 

 found in two series of stations extending offshore 

 from Oahu, Hawaii. Here the largest volumes 

 occurred at one or two miles from shore and the 

 difference between stations was significant (King 

 and Hida, 1954). Although the sampling was 

 entirely inadequate for any broad conclusions, it 

 appears evident that at the time of our visit to 

 Palmyra there was no definite gradient in zoo- 

 plankton abundance along four station lines 

 extending from a few hundred yards from the 

 outer reef to about 14 miles ofi'shore. 



2 4 6 8 10 12 14 16 



DISTANCE FROM 10 FATHOM LINE-MILF.S 



FioiTRE 22. — Zooplankton volumes (adju-sted) in relation 

 to di.stance oflshore from the 10-fathom line, Palmyra 

 I.sland, January 1953, Hugh M. Smith crui.se 19. 



