Date Approved


Date Posted


Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)



Committee Member

Steven Francoeur, Ph.D., Chair

Committee Member

Margaret Hanes, Ph.D.

Committee Member

Kristin Judd, Ph.D.


Algal photosynthesis can stimulate production of associated microbial heterotrophs; however,the mechanisms for this stimulation remain unknown. I incubated submerged Typha domingensis leaf litter in greenhouse mesocosms under low- and high-nutrient regimes and conducted microbial production assays after 79/80 (week 11) or 128/129 (week 18) days of colonization. I manipulated environmental factors (oxygen, pH, and labile organic carbon) affected by algal photosynthesis to test the hypothesis that one or more of these factors stimulates heterotrophic microbial production. In the low-nutrient treatments, bacterial production was increased by glucose addition during week 11 (p < 0.001) and by photosynthesis during week 18 (p < 0.05). Fungal production was stimulated by photosynthesis in the high-nutrient treatments during weeks 11 (p < 0.001) and 18 (p < 0.01) and by glucose during week 11 (p < 0.05). These results confirm that algal photosynthesis can increase heterotrophic microbial production and suggest that photosynthetic labile organic carbon (LOC) could be a stimulatory mechanism.

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