Joel Bonney

Date Approved


Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School


Committee Member

Steven Francoeur, PhD

Committee Member

Kristin Judd, PhD

Committee Member

Daniel Clemans, PhD


Algae can stimulate the production of heterotrophic microbes in periphyton communities, but the synergistic effects of light and temperature on this phenomenon are not well understood and have implications on carbon cycling and energy flow. We employed recirculating mesocosms held at different temperatures and light levels and filled with Typha litter and attached microbes to assess these effects. Heterotrophic microbial production was greater in the presence of light, as were some periphytic enzyme activities. Few response variables increased in a near-linear fashion with ascending temperature, suggesting different temperature optima. The strength of heterotrophic microbial production responses to algal photosynthesis did not vary with respect to temperature, but some enzyme activities did. The magnitude of light stimulation of bacterial production and several enzymatic activities were positively correlated, suggesting a similar driving mechanism. These findings advance our limited understanding of the synergistic effects of light and temperature on microbial communities.