to a lesser degree, the Siberian Seas. Since World War 

 II more attention has been given to the Beaufort and 

 Chukchi Seas and, with the use of floating ice 

 stations, the central Arctic. 



.Johnson (1963a, b) and Grainger (1965) ha%'e 

 reviewed zooplankton investigations in the central 

 Arctic. As in other oceans, the bulk of the net- 

 plankton consists of crustaceans, with copepods 

 predominating. The relative quantities of copepod 

 species depend on the depth at the localities sampled, 

 i.e., whether in shallow coastal seas or deep basins, 

 and also on the depth of the sample. In shallow seas 

 the most abundant species are Pseudocalanus 

 minutus s. 1.. Acartia longiremis. and several species 

 of Oithona and Oncaea. The predominant copepods in 

 the surface layers of the deep basins are Calanus 

 glacialis, C. hyperboreus, Metridia longa, 

 Microcalanus pygmaeu.s s. 1., Paraeuchaeta glacialis, 

 and Pseudocalanus minutus s. 1. 



With increasing depth in the central basins other 

 species become numerically more important, es- 

 pecially Scaphocalanus magnus, Temorites breuis, 

 and Spinocalanus species. The number of species 

 varies with depth, though the number of specimens 

 decreases. About 30 species are found in the upper 300 

 m, nearly 50 from 300 to 1,000 m, and about 20 below 

 1,000 m." 



Seven species of Spinocalanidae are reported from 

 the Arctic samples of the present study: Spinocalanus 

 longicornis, S. antarcticus, S. horridus, S. elongatus, 

 S. polaris, Mimocalanus crassus, and M. sulcifrons. 

 Numbers of each species in 142 samples from various 

 depth intervals are given in Table 2. No differences in 

 numbers of specimens or species of Spinocalanidae 

 were attributed to differences in the mesh sizes of 

 nets; the data from the 2 yr are not separated. 



None of the samples from above 80 m contained 

 Spinocalanidae. 



Spinocalanus longicornis — The depth range of 

 S. longicornis was 80-2,500 m. Adults were found 

 from 90 to 2,500 m, juveniles from 80 to 500 m. The 

 average concentration of total specimens was fairly 

 uniform between 90 and 400 m, decreasing sharply 

 above and below (Table 2). 



Other Arctic workers (see systematic review) 

 have included depths less than 80 m in the vertical 

 range of ,S. longicornis, but most of these records 

 are based on sampling intervals which included 

 greater depths. Brodsky and Nikitin (1955) 

 reported only one specimen in each of two samples 

 from 25 to 50 m, and two specimens from to 10 m, 

 although the species was common below 50 m. The 

 possibility of contamination in the 0-10 m sample 

 should not be overlooked; many surface samples 

 have been reported by other workers, and no other 

 occurrences between and 10 m have been noted. 

 Brodsky (1957) reported S. longicornis in low 

 numbers from 25 to 50 m, but indicated that it was 

 not present from to 10 m. Minoda (1967) reported 



a "very small number" of specimens, which were 

 probably .S. longicornis, from to 50 m. Hughes 

 (1968), in 399 samples collected with a plankton 

 pump, from 5 to 185 m at 5-m intervals, found low 

 numbers of S. longicornis in only one sample from 

 each of the following depths; 25, 40, 55, 60, and 75 

 m. 



Spinocalanus longicornis has been considered en- 

 demic to the Arctic, although in the present review 

 it is reported from the Atlantic, including the 

 Caribbean and Mediterranean, as well as from the 

 Pacific, with a depth range of 50-2,700 m. 

 Spinocalanus longicornis can be carried into the 

 Atlantic in the Arctic Water; it can also be brought 

 into the Arctic in the deeper Atlantic Water. 

 Perhaps there is some limited exchange of S. 

 longicornis in the near-surface water between the 

 Pacific and Arctic. 



Spinocalanus antarcticus — The depth range of S. 

 antarcticus was 140-2,500 m. Adults were found 

 from 200 to 2,500 m, juveniles from 140 to 2,000 m. 

 The highest average concentration occurred 

 between 180 and 300 m, with uniformly low 

 numbers to 2,500 m (Table 2). 



Reports of S. antarcticus are summarized in the 

 following systematic review. Most records are ba.sed 

 on sampling intervals which included depths below 

 140 m. Brodsky and Nikitin (1955) reported one fe- 

 male from 10 to 25 m. Johnson (1963a) found one 

 female between and 25 m. Dunbar and Harding 

 (1968) reported few between 0-50 m and 50-100 m. 

 Therefore its vertical range in the Arctic is at least 

 10-2,500 m, in low numbers in the Arctic Water 

 and Arctic Bottom Water and in greatest numbers 

 in the intermediate Atlantic Water. There would 

 seem to be no physical barriers to its movement in 

 and out of the Arctic. Its distribution into the At- 

 lantic has not been noted, but the species occurs in 

 the Pacific and Indian Sectors of the Antarctic (see 

 systematic review). 



Spinocalanus horridus — The depth range of S\ 

 horridus was 500-2,500 m. This species was found 

 only in very low concentration (Table 2). 



Reports of S. horridus are summarized in the 

 following systematic review. Most records are based 

 on very large vertical sampling intervals. Brodsky 

 and Nikitin (1955) reported several females 

 between 100 and 270 m and one male between 25 

 and 50 m; Minoda (1967) found one probable S. 

 horridus between and 200 m. These occurrences 

 are rare; most records indicate an upper depth 

 limit between 300 and 500 m. 



Spinocalanus horridus can freely enter the Arctic 

 in the Atlantic Water, and a few specimens are 

 probably carried to the Atlantic in the Arctic 

 Water. Spinocalanus horridus has a virtually 

 worldwide distribution and a great vertical range 

 everywhere. 



11 



