Abstract |
A series of lake-long transect tows were made with the Continuous Plankton Recorder in Lakes Superior, Michigan and Huron, 1966-68. All tows were made at ten meters depth with either no. 60 mesh Grit Gauze or no. 15 mesh Silk Bolting cloth. Information was obtained on organism distribution in both space and time. The density and distribution of ecologically related groups in plankton indicate the relative tropic status of the bodies of water sampled. Lake Superior is the most oligotrophic, Lake Huron the most eutrophic and Lake Michigan more mesotrophic. A mean of 200 to 300 organisms per section was seen in Lake Superior; a range of 5,000 to 6,000 organisms per section was seen in Lake Michigan and from 20,000 to 21,000 organisms were observed from one year to another and from one season to another. Marked variations in both numbers and species of organisms were evident in the lakes. Limitations of the Continuous Plankton Recorder method are described. (WRSIC abstract) |