Date of Award
Cladophora glomerata, a filamentous green alga abundant in the Laurentian Great Lakes, has long been considered a nuisance throughout the region. Previous phosphorus (P) abatement practices and legislation successfully reduced the abundance of the algae, but with the introduction of dreissenid mussels, a resurgence has been observed. Though there is substantial literature and modeling of the growth cycle of Cladophora, relatively little research has been dedicated to the decomposition stage of the algae, a period which may contribute to a substantial influx of nutrients to near-shore environmental regions. By first examining a period of in-situ growth within Lake Ontario, I established a baseline of expected biomass accrual and nutrient content of both healthy algal tissue and water in the sample area. While nuisance biomass levels were not observed during this period, tissue nutrients suggested P limitation in the region even though the water column was dynamic and well mixed. In-situ growth dynamics were coupled with a full factorial in-vitro experiment examining the loss of nutrients, from tissue to water through decomposition. An abiotic variable (wave action), and a biotic variable (herbivorous crayfish, Faxonius propinquus), were introduced as decomposition contributors. While all treatments resulted in greater than half of the tissue mass lost, there did not appear to be any treatment effect with all replicates experiencing similar loss throughout the 20 days. Although the algae was detached when collected, it was still alive and productive for up to 10-days after the start of the experiment, evidenced by tissue and water nutrient changes. While final nutrient concentrations in tissue and water did mirror each other for all treatments, the capacity for crayfish to limit the epiphytic community appeared to have the greatest effect in contributing to nutrient loss to the water column.
Wagner, James L. Jr, "Filamentous green algae (Cladophora glomerata) in near shore Lake Ontario: an investigation of tissue and water nutrient dynamics through a period of growth and decomposition." (2022). Biology Theses. 50.