49] 
PLANKTON PRODUCTION IN MATANZAS LAKE COMPARED WITH THAT IN 
QUIVER AND DOGFISH LAKES. 
Date Matanzas Lake Gave race | Dogfish Lake 
Gea eee eal!) iss as as 
ASAP re TG cee be 
eo ee neh pie a ct ea ae Til 
ee an: oe a ee ele Sore 3.9! 
Fe eae re [lala “free ren 
ee eee eee wa hae ce tilveae. al aesenn 
tree cle ce (i eee ae a 
of collection above indicated is approximately twice that of 
Quiver and Dogfish lakes, where vegetation was at that time 
somewhat more abundant. In 1896 Quiver Lake was freer from 
vegetation than at any other time in the period of our opera- 
tions, and the contrast between the production of the two 
lakes appears greater if we consider other years or the average 
for all collections in the months named. On the latter basis 
the ratio rises to 3 to 1 for July and 8 to 1 for August in the 
comparison of Matanzas and Quiver lakes. In the case of Dog- 
fish Lake the contrast is less striking, but still evident. Ma- 
tanzas Lake, similar in its environment to Quiver Lake save in 
the matter of vegetation, thus produces a more abundant plank- 
ton, and we may infer that the vegetation of the latter is in- 
imical to the development of plankton in its waters. 
A second line of evidence bearing upon the question under 
discussion is to be found in the production in Quiver Lake itself 
under different conditions of vegetation. In 1894, and still 
more in 1595, owing to low water in early summer, vegetation 
was very abundant in Quiver Lake. The growth of Cerato- 
phyllum and Elodea choked its waters from shore to shore and 
from bottom to surface except in a narrow poorly defined chan- 
