Periphyton community dynamics in varying natural environments : a study from Northern Lake Simcoe / by Deborah Lynn Balika.

Globally, freshwater ecosystems are constantly under the threat of various biological and chemical stressors. In Canada, millions of dollars are spent on the rehabilitation process of these water bodies every year. Maintenance of healthy water systems is important for their conservation and survival of human kind. This study examines the use of periphyton as a tool for monitoring water quality by examining the dynamics (biofilm thickness, species density, species richness, species diversity, and biomass) in periphyton communities in lentic environments. Previous research validates the successful use of periphyton in lotic environments. This multi-proxy (Bacillariophyceae, Chlorophyceae, Cyanophyceae, and protozoa) study investigated the colonization pattern of periphyton on inert glass slides (10 X 3 X 0.1cm) suspended in the littoral zone of 3 sampling locations in northern Lake Simcoe, to a maximum period of 30 days (per sampling period) with intermittent sampling. The study was repeated four times in different seasons during 2011-2013. The retrieved slides were observed under a microscope for taxonomic composition of periphyton communities, species density, and biofilm thickness. The hypotheses tested were (1) periphyton community dynamics vary with season and location, (2) species diversity decreases as a result of increase in nutrient concentration, (3) diatom abundance and species composition will increase in spring and fall seasons as a result of lake turnover processes. Results indicated that there was significant variation in the periphyton colonization pattern with seasons, locations and with the duration of slide exposure. The overall periphyton growth (biofilm thickness, biomass and species density) exhibited an increase during the early phase (rmAnova p<0.05 between days of exposure); a climax during the mid phase (miAnova /7<0.05 between days of exposure); a sloughing-off period, and an increase in growth towards the late growth phase (rmAnova /7<0.05 between days of exposure). The highest species density (site LC: 7.91iogio) was observed during summer (rmAnovap<0.05 between seasons) when a decrease in diversity in Bacillariophyceae was observed. However, Bacillariophyceae abundance and diversity increased during spring and fall sampling periods as a result of lake turnover processes and the availability of nutrients. Overall species diversity did not decrease when the total phosphorus concentration increased in the water column. This is mainly because of the increased diversity in Chlorophyceae, Cyanophyceae and protozoa. The periphyton community varied with the environmental stressors such as variations in conductivity and nutrient concentrations. Thus, the mature periphyton community composition and their dynamics demonstrated that they can be used as an indicator of water quality changes in this study area. Lay summary The mission statement of Lakehead University’s Department of Biology is "Faculty and students in the Department of Biology are bound together by a common interest in explaining the diversity of life, the fit between form and fimction, and the distribution and abundance of organisms. " The current study focuses on the dynamics of periphyton, which is a multidimensional matrix composed of an initial layer of bacteria on a substrate followed by the attachment of algae, protozoa, and various invertebrates. This study contributes to one of the central research themes outlined in the mission statement, the relationships between life forms and their environmental functions. The study advances our understanding of various biotic and abiotic factors influencing periphyton growth in near-shore lake environments. Understanding the succession of periphyton communities and their environmental niches is a valuable tool in assessing water quality as periphyton members are able to rapidly respond to physical and chemical stressors. Three major research questions were investigated. 1. What are the effects of seasonality and nutrient concentrations on periphyton? 2. How periphyton growth patterns relate to water quality? 3. Can the periphyton composition represent the nutrient availability of each sampling site? Results showed that the species composition varied considerably between sites and sampling periods and that nutrient concentration influenced the presence or absence of certain species. This study provides a baseline dataset for periphyton and water quality measurements in northern Lake Simcoe. Furthermore, it may be useful to the development of a periphyton based water quality index for northern Lake Simcoe which will assist scientists and policy makers in their efforts towards more efficient water resources management.