Olthona .similis, also appearing frequently. Adult 

 Parevrhaef/i glaridlis^ Scaphocalanus magnus, 

 Cnlamtf! ftunarchicus, Gaidms tenuspinus and 

 rh Indus ohfus/frons appeared in collections from 

 depths greater than 150 metres though very 

 young forms of these species often appeared in 

 tows made at 100 m. During early September, in 

 conjunction with a heavy phytoplankton bloom, 

 all stages of copepodite development were noted 

 but later in September very few animals younger 

 than stage IV were observed. The numbers of 

 adults in the population also decreased after the 

 phytoplankton bloom liad finished. In general, 

 older forms were found at greater depths than 

 were the young of their species. 



Atlantic forms were found in tows only at 

 depths greater than 125 metres. These forms ap- 

 peared below the thermocline and their relative 

 abundances were highly variable. Due to its 

 abundance in tows taken, the Atlantic copepod 

 f. ftunftrchwu.s, is the best indicator of the pene- 

 tration of Atlantic water into the North Water 

 region. The extent of its penetration toward 

 Smith Sound is unknown because results from 

 the Station 44 (lat. 77°51' N., long. 74°40' W.) 

 are inconclusive. High winds and ice prevented 

 any collections being made in Smith Sound dur- 

 ing the period the ship was in the region. The 

 exact depth at which Atlantic forms occur is not 

 known because closing nets were not used. How- 

 ever, the surface layer to a depth of 75 to 100 

 metres was inhabited primarily by the Arctic 

 species f'nJunvs glacialis and Calamis hyper- 

 horeun. 



Three species of Chaetognath, Euhronm hnmn- 

 tn. ^iigitfn elegcnis. and Sfigitfa mixhna occurred 

 in the samples. They occur in all three water 

 masses being considered but those forms which 

 breed in Arctic water have spots on their fins 

 which are thought to be sensory in nature. The 

 presence or absence of these spots combined with 



the lengths of the individuals suggest the same 

 conclusions drawn from the copepod analysis. 

 Both Eukronia hamata and Sagitta elegans col- 

 lected from the upper 100 metres of the water 

 column show longer average body size and a 

 higher percentage of spotted finned individuals 

 which suggests strong Arctic water influence. At 

 depths of 100 to 200 metres, the average size 

 decreases as does the percentage of chaetognaths 

 with spotted fins, indicating the greater influence 

 of Atlantic water at this depth. The horizontal 

 distribution of Eukronia hamata was more uni- 

 form tlian that of Sagitta elegann, making the 

 former species better indicator in this region. S. 

 elegans only appeared in 50% of the samples 

 collected and in much fewer numbers. 



SUMMARY 



The results obtained from the copepod and 

 chaetognath collections indicate a very strong 

 Arctic influence in the surface waters, these 

 waters being populated by the Arctic copepods 

 Cal<iniin glaci/ilis and f. hyperhoreiift and the 

 chaetognaths Euhronia hamata with spotted fins. 

 The appearance of the copepod Cahnus fn- 

 marchicits and of the Chaetognath species bear- 

 ing fewer spots on the fins indicates a high degree 

 of Atlantic influence between 100 and 200 meti-es. 

 Too few tows were made deeper than 200 metres 

 to draw any conclusions from the specimens ob- 

 tained from these depths. 



In the future, collections using closing nets 

 must be made to determine more exactly the 

 distribution of the populations present in the 

 different water masses. A more extensive sam- 

 pling program in Kane Basin, Smith Sound, 

 Jones Sound and Lancaster Sound will be nec- 

 essary for a better understanding of the plank- 

 tonic distributions, particularly those of the At- 

 lantic species and of any Pacific forms that may 

 penetrate into the North Water region. 



22 



