7 GEORGE V SESSIONAL PAPER No. 38a ; A. 1917 
THE WINTER PLANKTON IN THE NEIGHBOURHOOD OF ST. ANDREWS, 
1914-15. 
By Proressor J. Puayrairn McMurricu, M.A., Ph.D., Professor of Anatomy in the 
University of Toronto. 
With the object of determining the general character of the winter plankton in 
the vicinity of the Biological Station, St. Andrews, N.B., the caretaker of the station, 
A. B. Calder, was instructed to make collections of the plankton during the winter of 
1914-15, and to preserve the material collected in formalin. Collections were con- 
sequently made at frequent intervals from the latter part of September, 1914, until 
the end of May, 1915, and in what follows, the results of a qualitative 
study of the collections are given. Acknowledgment must be made of the conscientious 
manner in which Calder fulfilled the task with which he was entrusted, the collec- 
tions having been made with sufficient frequency to give an excellent idea of the 
character of the winter plankton, and the material being well preserved. Two 
coliections were taken at each station in the majority of cases, one at the surface 
and one at a depth of about 6 metres (3 fathoms), and at each station the tempera- 
ture of both the air and the surface-water was taken, and the condition of the tide 
noted. The only misfortune that occurred was the loss of the labels of some of the 
collections, chiefly of those made in the early autumn, so that these collections cannot 
be included in the table which forms an appendix to this report. Their omission, how- 
ever, does not modify the qualitative character of the plankton as shown by the remain- 
ing collections. 
In studying the collections, the volume of the material contained in each one was 
measured, and since nets of the same mesh were used throughout and the time of 
the towing was the same, i.e., twenty minutes for each collection, the amounts 
obtained indicate approximately the relative abundance of the plankton in the different 
gatherings of the series. Obviously, however, they furnish no indication of the 
absolute amount of material present in the water of Passamoquoddy bay, since no 
data were available as to the volume of water filtered through the nets during the 
towing. So many factors, uncontrollable in the series of collections under con- 
sideration, enter into the question of the determination of the absolute plankton 
volume, that it did not seem worth while to attempt an estimation of the volume of 
water filtered by the nets. The amounts obtained have, therefore, only a relative 
interest. One feature is, however, shown very clearly by the figures, namely, that with 
rare exceptions the collections from the 6-metre level were considerably larger than 
those from the surface. This may or may not have a bearing in the distribution of 
the plankton, since the conditions under which the collections at the two levels were 
made were not quite identical, the surface collections having been made with a net 
of finer mesh than that used at the 6-metre level. The greater fineness of the sur- 
face net may have caused so much diminution of flow through it, that much less 
water was actually filtered by it than by the 3-fathom net, in which case a less 
amount of plankton, even though its distribution were uniform at both levels, would 
be expected in the surface collection. In future series the conditions for the gather- 
ings at the two levels will be made more uniform, and it is hoped that a definite 
result will be obtained as to this question of distribution. 
Samples were taken of each collection and, so far as possible, the various forms 
observed in each were identified and recorded, an attempt being made to indicate 
38a—1 
