6 A Canadian Arctic Expedition, 1913-1918 



List of Freshwater Algae found in brackish ponds. 

 Teller, Alaska. Bernard harbour, N.W.T. 



Chroococcus turgidus 



Eudorina elegans 



Pediastrum Boryanum Pediastrum Boryanum 



Pediastrum integrum 

 Enteromorpha intestinalis 

 Ulothrix variabilis 



Microspora sp? (fragments) 



Spirogyra inflata ? (no spores) 



Closterium striolatum 



Cosmarium granatum Cosmarium granatum 



Cosmarium punctulatum Cosmarium punctulatum 



Cosmarium humile var. striolatum 



Cosmarium radiosum (one only) 



Staurastrum punctulatum 



Oedogonixim sp? (fragments) Oedogonium sp? (fragments) 



Bulbochaete sp? 



Ophiocytium majus 



In addition to these numerous diatoms were found including Epithemia 

 turgida, E. gibba, E. Sorex, species of Cymbella, Eunotia, Navicula, etc. 



After a consideration of the local climatic and geographic factors, I think 

 that the explanation of the presence of these distinctly freshwater plants in 

 water which is brackish to the taste is that the ponds contain two distinct floras 

 which flourish at different times during the short summer season — a freshwater 

 flora of green algae and freshwater diatoms which flourish in the earlier part 

 of the season, and a marine diatomaceous flora which flourishes in the latter 

 part of the season. 



The freshwater flora becomes active with the advent of summer. The 

 fresh water, melted on the slopes further inland, probably flowing through bogs 

 or pools of fresh wat?r, would bring freshwater algae to the brackish ponds where 

 the surface ice would be beginning to melt. The resting stages of algae, left 

 near the margin of the pond by evaporation the previous year, would begin 

 active life again as fast as the rising water covered them. These plants, and 

 those brought in by the influx of fresh water, would flourish during the earlier 

 part of the summer. By the middle of June, when all the ice of the pond had 

 melted, a brackish or marine flora would become active and remain so until 

 arrested by the approach of winter. 



The evaporation of the surface waters would leave many freshwater algae 

 stranded, whilst others would cease activity under the influence of the slowly 

 increasing salinity of the water. The stranded plants, in most instances, would 

 assume or form some resting state which would enable them to survive the 

 adverse conditions of winter and take up active life again the following year. 



Many of these typical freshwater forms must be subjected to some extent 

 to brackish conditions and yet they survive. Probably many can exist in slightly 

 brackish water, with a slightly retarded metabolism, as long as the season lasts. 

 As the salinity increases, some may be induced to develop spores and rest until 

 the influx of fresh water the following summer. Judging by the number of 

 individuals, I think that certain species, e.g., Pediastrum Boryanum and 

 Cosmarium punctulatum, can adapt themselves to a nearly normal existence 

 even in parts of these ponds where the water is distinctly brackish. Experi- 

 mental observations under natural conditions would be of great value, if carried 

 out; but, unfortunately, laboratories cannot be established readily in arctic 

 swamps. 



