PLANKTON OF THE WOODS HOLE REGION 111 
alternating with clear areas. It may be that patches like these formed the pulses 
of which Allen speaks, for his collections were on the open coast and taken from the 
end of a wharf past which the belts of uneven abundance would drift. 
The seasonal variation of the diatom maxima and the appearance of oceanic 
species in local waters can be understood best by considering the geographical 
position of Woods Hole as compared with other areas of the eastern and western 
Atlantic. Steuer (1911) found that in general the maxima of the various species, 
ee ee ee 
Karajakfjord in Greenland 
‘Nerth European Coast 
Skager Ralc 
Fic. 13.—Schematic diagram of the seasonal distribution of the diatom maxima in the northern and southern parts of the eastern 
Atlantic. After Steuer 
both neritic and oceanic, is closely related to temperature, and thus varies according 
to the latitude. It has long been known that on both the European and American 
coasts the most luxuriant diatom growth does not take place in the warmest months 
even as far north as Norway and Newfoundland. 
At Karajakfjord, in Greenland, Vanhéffen (1897) found only one maximum, 
from May until the beginning of September. South of this there occurs the typical 
spring and fall maxima, which retreat farther and farther from the warmest seasons 
as one approaches the Tropics. Steuer (1903) found that this constant succession 
of diatom maxima toward the south necessarily leads to the assumption that some- 
where in the south there will be a meeting of the two maxima in winter, and this 
was found to occur in the Adriatic Sea by Leder (1917), Steuer (1903), Stiasny (1908), 
and Gran (1909) (fig. 13). A smaller maximum was also found to occur in June and 
July. Conditions on the American coast are surprisingly similar to those of the 
eastern Atlantic (fig. 14). 
ee 
re ee 
Bay of Femdy 
Massachusetts Bay 
Vineyard Sound and 
Buzzards Bay 
Long Island Sound 
Fig. 14.—Schematic diagram of the seasonal distribution of the diatom maxima on the western Atlantic coast 
Observations in eastern Canadian waters by Bailey, MacMurrich, and Fritz 
show that the greatest maxima occur in the spring and fall. Bigelow (1917) com- 
mented on the similarity of the diatom distribution in the Gulf of Maine and that 
of the North Sea, Irish Sea, and Skager-Rak. He also found a great maxima in 
Massachusetts Bay in April and early May, 1913, and a smaller one in September, 
1915, and one in late August, 1922. 
The striking effect of the arm of Cape Cod on the plankton is again evident 
here, for within 20 miles of latitude of Massachusetts Bay conditions similar to 
those of the Mediterranean and Adriatic Seas are found in Buzzards Bay. Here 
and throughout the shallow waters south of Cape Cod a rich winter diatom plankton 
