THE PHYTOPLANKTON OF THE MUSKOKA REGION, 
ONTARIO, CANADA 1 
Gilbert Morgan Smith 
This report on a reconnaissance survey of the August and Sep¬ 
tember phytoplankton in the lakes of the Muskoka region in 
southern Ontario represents an extension to another region of the 
type of survey which I have been carrying on in the State of 
Wisconsin for the past few seasons. The Muskoka region was 
chosen because lakes are abundant and because of the geological 
nature of the district. The expectation, on the basis of the Wests’ 
theory of geological correlation, that the region would prove rich 
in desmids was fully realized, and many lakes were found with 
a rich desmid flora. 
The general nature of the plankton flora is much the same as 
that of other lakes in areas of old igneous rocks: namely, small 
bulk of plankton, scarcity of Myxophyceae, and few species of 
Protococcales. In general, the same organisms are found in On¬ 
tario as in Wisconsin, but the relative abundance is not the same. 
Thus, for example, Pediastrum Boryanum, Kirchneriella obesa, 
and Coelastrum microporum are widely distributed in Wisconsin 
but poorly represented in the plankton of Ontario. Conversely, 
Pediastrum araneosum, Dimorphococcus lunatus , and Dactylococ- 
copsis rhaphidioides are much more abundant in Ontario. The 
most striking feature of the desmid portion of the plankton in 
Ontario is the frequent occurrence of Staurastrum limneticum var, 
burmense, an alga that has been recorded from but a single lake 
in Wisconsin. A comparison of the desmid floras of the two 
regions will not be made at the present time since the account of 
the Wisconsin region has not, as yet, been completed. 
1 These investigations were made possible by grants for traveling expenses 
from the Research Fund of the American Association for the Advancement of 
Science and from the Research Fund of the University of Wisconsin. 
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