Title: Survey of the Phytoplankton Communities Involved in Oxygen Supersaturation Under the Ice in Shallow North Dakota Lakes

Focus Categories: Water Quality, Ecology, Wetlands

Project No. ND94-05

Principal Investigator: Marvin W. Fawley - Department of Botany/Biology, NDSU

Completion Report

Fawley, Marvin W. and Karen A. Phillips, 1997, Phytoplankton Communities Associated with Elevated Oxygen Levels Under the Ice in Shallow North Dakota Lakes, Rept. No. ND94-05, North Dakota Water Resources Research Institute, North Dakota State University, Fargo, North Dakota, 6 pages.

Other Publications

Phillips, Karen A., 1998, Phytoplankton Community Structure under Ice in Shallow North Dakota Lakes, “Ph.D. Dissertation,” Department of Botany/Biology, North Dakota State University, Fargo, North Dakota, 96 pages.

Phillips, Karen A. and Marvin W. Fawley, 1996, Winter phytoplankton Assemblages in North Dakota Lakes, in Proceedings Fifth North Dakota Water Quality Symposium, B.D. Seelig, ed., March, 1996, NDSU Extension Service, pages 17-21.  

Significant Findings

It was found that blooms of several organisms, particularly a dinoflagellate and several species of cryptomonads, are associated with high DO levels that occur in shallow North Dakota lakes in late February and early March. However, these blooms do not occur every year. It is likely that the bloom is initiated by the germination of cysts of the dinoflagellate found in the sediment. Many phytoplankton are present during the winter, and the winter season is an active period for phytoplankton despite the short days and low light levels. The results challenge the accepted ideas of phytoplankton seasonal dynamics, which hold that very little phytoplankton growth occurs during winter.An unexpected diversity of very small green algae was found in the Arrowwood lakes. Traditional keys essentially useless for the identification of these organisms, and new methods were developed. To date, nineteen different “species” have been identified among the isolates, only one of which matches any named organism. These results show that the diversity of these organisms is much higher than was previously suspected. The methods employed for identification also will allow the ecology and distribution of these organisms to be studied for the first time.