Danielssenia sibirica Group — Wilson 
known records are north of the Arctic Circle. 
The range of distribution is from the east 
central coast of Greenland to the Chukchi Sea 
coast of Alaska, from about 68°-71° N and 
24°-l65° W. 
All collections of Willey and Jespersen were 
from coastal plankton tows. Those of Willey 
were probably made in brackish waters. The 
Alaskan records are from landlocked coastal 
bodies of water. Nuwuk Lake has been de- 
scribed by Mohr et al. (1961) and Holmquist 
(1963), and features relative to its copepod 
fauna are given in Wilson (1963). Significant 
features are: surface area about 2.5 ha; maxi- 
mum depth 5. 2-5. 6 m; slightly brackish surface 
waters (about 5-8 0/00) ; bottom salinity 
about 60 0/00; ice-free period 2 months or 
less (July- August ) . Copepod associates of D. 
stefanssoni were species of marine and brackish 
waters having varying degrees of euryhalinity 
within genus or species. 
Lagoons of the Cape Thompson region have 
been studied with respect to their copepod 
fauna by Johnson (1961) and Wilson and 
Tash (1966). Collections were made only as 
plankton tows and harpacticoids were rare in 
the samples examined by me from eight la- 
goons, reflecting the method of sampling rather 
than the actual presence or absence of the 
group. Although D. stefanssoni was found in 
only two lagoons, it may well be a habitant of 
most of the lagoons along the coast. 
Physical features of the lagoons are relatively 
low salinity, shallow depth (maximum, 3 m), 
and freedom from ice cover for about 2y 2 -3 
months. Salinity recorded on several dates in 
1959-1961 for Pusigrak Lagoon was always 
very low (0.08-0.35 0/00). Mapsorak Lagoon 
likewise had very low salinity (0.4-0.87 0/00) 
in 1960-1961 when D. stefanssoni was col- 
lected, but Johnson recorded salinity of 14.31- 
15.96 0/00 in August 1959, at which time a 
large number of neritic calanoid species were 
present. Since these were not collected in 1960- 
1961, it has been assumed that the lagoon had 
been flooded with sea water during a storm and 
at least part of the copepod community was 
temporal (Wilson and Tash, 1966). 
In the literature and new records given 
herein, collections have all been made by 
plankton tows, and D. stefanssoni occurred only 
443 
in small numbers, mostly as adults in middle- 
late summer. Presence of adults in late June in 
Cape Thompson lagoons, as contrasted with 
later dates in the Barrow region, may be due 
to earlier development resulting from higher 
temperatures earlier in the season with a longer 
period of ice-free water. Most records seem to 
indicate that maturity of the summer genera- 
tion is attained late in the season and that the 
adults have some degree of planktonic motility. 
Knowledge of the life history of the species, 
through occurrence of its developmental stages, 
apparently can be acquired only by methods 
directed specifically at collection of harpacti- 
coids during what represents early summer for 
any given region. 
ACKNOWLEDGMENTS 
Financial support for field work came from 
the Office of Naval Research (Nuwuk Lake; 
collections referred to me by Dr. J. L. Mohr) 
and the Atomic Energy Commission, Project 
Chariot (Cape Thompson region; collections 
referred by J. C. Tash). My studies have been 
supported by National Science Foundation grant 
G21643 to the Smithsonian Institution. I am 
indebted to Mrs. Mary Newton for completion 
of illustrations of the male appendages, to 
Miss Sandra Parker for assistance with the final 
manuscript copy, to Dr. Paul Illg and Mr. 
David Damkaer for gifts of some of the per- 
tinent literature. 
REFERENCES 
Borutsky, E. V. 1952. Flarpacticoida presnykh 
vod. Fauna SSSR, Rakoobraznye, III (4) . [In 
Russian.] Zool. Inst. Akad. Nauk SSSR, n. 
s., No. 50, 425 pp., 116 figs. 
Brady, G. S. 1880. A Monograph of the Free 
and Semi-parasitic Copepoda of the British 
Islands, Vol. 2. Ray Society, London. 182 pp., 
pis. 34-82. 
Holmquist, Charlotte. 1963. Some notes on 
Mysis relicta and its relatives in northern 
Alaska. Arctic 16(2) :109-128, 7 figs. 
Jespersen, P. 1939^. Investigations on the 
copepod fauna in East Greenland waters. 
Medd. om Gr0nland 119(9) :1 — 106, 37 
figs. 
