Biological Survey — Erie-Niagara Watershed 



65 



SURFACE 

 03 05 



OOCYSTIS 



SPHAEROCYSTIS 



STAURASTRUM 



ANABAENA 



ASTERIONELLA 



TRAGI LARiA 



MELOSIRA 

 STEPHANODISCUS 



TABELLARIA 



CERATIUM 



DINOBRYON 



POLYARTHRA 



ALGAE 



DIATOMS 



PROTOZOA 

 ROTIFERS 



05 Ob 



Fig. 6,— Relative abundance and seasonal variation (at the surface and bottom) 

 for dominant genera and large groups of microplankton. The number 

 of organisms is plotted against time. The trips are of the dates: 01, 

 July 30-Aug. 1; 03, Aug. 15-17; 05, Aug. 28-Sept. 3; 06, Sept. 12-14; 28. 



