Arctic Zooplankton — Johnson 
315 
the University of Washington from collections 
made near the outlet on Aug. 22, 1959. These 
are the only known locality records for the 
American coast. Elsewhere the species occurs on 
the Asian coast. 
The other neritic species encountered are 
quite common in small numbers on the Alaskan 
coast to Point Barrow and in diminishing num- 
bers eastward (Johnson, 1953, 1956). 
In lagoon no. 4 south, the plankton was 
sparse and Acartia bifilosa was the most nu- 
merous copepod in the surface water on Aug. 
6, but an unidentified harpacticoid was the dom- 
inant form at the bottom on Aug. 13. It is 
probably a benthic species since the net con- 
tained much bottom debris. Intermingled in the 
plankton on both dates were the neritic cladoc- 
erans, Podon and Evadne , as the chief evidence 
of marine invasion. 
The plankton fauna of all of the remaining 
lagoons in the numbered series was characteris- 
tically fresh-water. However, there was still a 
strange marine affinity evidenced by the pres- 
ence of Limnocalanus grimaldi and L. johanseni. 
The former species was common in lagoon no. 
1 north, and the latter in all other lagoons with 
the exception of no. 2 south. The species of 
this copepod genus have long been the subject 
of much speculation with respect to their geo- 
graphic distribution and affinities to the sea. 
One species, L. macrurus , commonly occurs in 
deep fresh-water lakes, and is generally believed 
to be a marine relict of glacial times. L. grimaldi 
is an Arctic marine and brackish-water form 
occurring along the Arctic coast of the U.S.S.R. 
and is also considered to be a relict of Arctic 
fauna when found in such widely different iso- 
lated localities as the Caspian Sea, the Gulf of 
Bothnia, and the Baltic Sea. Aside from its 
present occurrence in lagoon no. 1 north, it has 
been reported from the Alaskan coast on two 
previous occasions, once from a collection taken 
about 100 yd. from the shore at Collinson Point 
(Willey, 1920), and once at a series of nine 
offshore stations in the same region, and off the 
mouth of the Colville River (Johnson, 1956). 
The present discovery is therefore of special 
interest in extending the known range of the 
species on the Alaskan coast, and in recording 
its occurrence in virtually fresh water, together 
with Eurytemora foveola n. sp. that apparently 
thrives best at very low salinities. 
Less is known about the distribution of Lim- 
nocalanus johanseni. It was originally described 
by Marsh (1920) from a fresh-water pond at 
Collinson Point, just inland from, but not con- 
nected with, the shore where Willey recorded 
L. grimaldi. Subsequently, Comita and Edmond- 
son (1953) reported it from Imikpuk Lake, a 
fresh-water lake near Point Barrow. In the pres- 
ent survey it was a conspicuous element ranging 
from small to dominant numbers in all lagoons 
except no. 2 south, the one which most nearly 
approaches marine conditions. In lagoon no. 5 
south, it was extremely abundant, and although 
a considerable number of early copepodid stages 
occurred mingled with adults no nauplii were 
observed. This agrees in general with the ob- 
servations of Comita ( 1956) in a more ex- 
tensive analysis which indicated that the eggs 
of this species in Imikpuk Lake hatched early 
in spring, and only copepodid stages are to be 
found in late July and August. His data show 
no nauplii after Jul. 31 and the first appearance 
of adults (copepodid stage VI) was on Aug. 
10. In the present collections from lagoon no. 
5, adults already outnumbered the other stages 
on Aug. 6, when the first sampling was done. 
Comita concluded that L. johanseni in Imikpuk 
Lake produces only one generation a year and 
that the species winters over in the egg stage. 
This agrees with the known life cycle of an- 
other fresh-water species, L. macrurus , discussed 
by Gurney (1931). Another similarity between 
the populations of Imikpuk Lake and lagoon 
no. 5 south was the presence of at least two 
size groups. This bimodality was not so pro- 
nounced in the males as in the females, but 
some tendency is shown (Fig. 2). The present 
analysis of the population applies only to the 
standing crop at the time of sampling, and 
hence further comparisons cannot be made other 
than to note that the large-size group was the 
most abundant. But it cannot be said whether 
they were produced before or after the small- 
size group. 
TAXONOMIC NOTES 
The following observations can be made re- 
garding a few of the species encountered. 
