150 Conservation Department 



July. One of the Peridineae was common, especially near the 

 surface during the latter part of the season. The figures for 

 Protozoa probably are very incomplete. The more delicate forms 

 were probably lost when the samples had to be preserved for later 

 examination. 



Observations show that Seneca lake, like Cayuga lake, was 

 relatively poor in plankton organisms. The samples taken in 

 June contained very few organisms except AsterioneUa. 



Seneca Lake. — Observations show that Seneca lake, like Cayuga 

 lake, was relatively poor in plankton organisms. The samples 

 taken in June contained very few organisms except AsterioneUa. 



Net plankton. Cladocera. — These organisms were never abund- 

 ant in Seneca lake. At the south station Pseudosida, Daphnia and 

 Bosmina occurred in very small numbers at various depths in 

 August and September but were absent in June and July. At 

 the north station a few Bosmina and Daphnia were found in July 

 and August and traces of Leptodora and Polyphemus were found 

 in 'the latter part of the season. 



Copepoda. — Diaptomus and Cyclops were found in nearly all 

 samples but appeared in largest numbers during July and August 

 in the upper 15 meters. Nanplii were fairly abundant at all times 

 in the upper 15 meters. 



Kotifera. — No rotifers were found in the June samples and 

 only small numbers appeared later. Anuraea and Polyarthra 

 were found in small numbers at various depths at both stations. 

 Asplanchna appeared in traces near the surface. Conochilus and 

 Notholea were found at the north station on July 18. Triarthra 

 was found once, 40-50 meters, at the south station July 16, and 

 Pleosoma was found in three samples, 0-10 meters at the south 

 station September 6. 



Protozoa. — Ceratium was absent in June, appeared only in 

 traces in July, and became rather abundant between 0-15 meters 

 during August, Dinooryon was found much more irregularly 

 than in Cayuga lake. Small numbers of Vorticella, attached to 

 Anaoaena, and Difflugia were found near the surface in the latter 

 part of the season. 



Phytoplankton. Cyanophyceae. — Anabaena appeared near the 

 surface at the north station on August 20 and between 0-20 meters 

 at both stations on September 6, but at no time was it very 

 common. Microcystis appeared in all but the deepest samples on 

 August 20, but only traces were left by September. 



Chlorophyceae. — Members of this group were very rare. Only 

 a few traces of Actinastrum, Sphaerocystis and Staurastrum were 

 found. 



Bacillariae. — The most common diatom was AsterioneUa which 

 was most abundant near the surface early in the season. Fragilaria 

 was found in the latter part of the season. Tabellaria was found 

 in traces in only a few samples from near the surface. 



