Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

2008

Thesis Director

Charles Pederson

Thesis Committee Member

Scott Meiners

Thesis Committee Member

Jeff Laursen

Abstract

In the last two decades management and monitoring efforts in freshwater systems has shifted from point source pollutants to non-point source pollutants and environmental modification. Long term, large scale sampling projects necessitated by such a shift often are infeasible due to logistical, cost, and time constraints.

In recent years fish and benthic macroinvertebrate indices of biological integrity (IBI's) have been used to survey the quality of flowing (lotic) water systems, which have drastically reduced sampling time and facilitated large scale monitoring projects. However, it is unlikely that these could be adapted to lentic systems. This study was undertaken in an effort to produce phytoplankton-based IBI' s that can be used to indicate the quality of a freshwater system. Phytoplankton have been widely recommended as indicator organisms for lentic systems, but presently there have been few studies exploring the feasibility of developing IBI's based on phytoplankton assemblage structure.

Through the NLA and ILA I was able to collect environmental and algal assemblage data from 50 lakes within the state of Illinois, during a single season. I then used these data to validate models that were previously developed from a large historical data set. My analyses showed that temporal variation in assemblage structure was not significant between the months of June and August. I was also able to confirm that the regional distinctions used for the state of Illinois are valid.

Through this study and that ofRasmussen (2007) I was also able to identify key indicator taxa for the state of Illinois as well as regionally indicative taxa for the southern, central, and northern regions. Meaningful clustering of lakes also was evident when based on higher-level taxa, indicating that there may be a significant link between phytoplankton assemblage structure and physical and chemical variables.

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