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Sonia Mae Johns - Phytoplankton Lab

Clarkson University, Potsdam, NY

Alkaline phosphatase enzyme activity was studied in the Rhode River estuary. A bulk alkaline phosphatase assay and  a new intracellular labeling system (ELF-97) were used to study the estuaries temporal and spatial patterns in alkaline phosphatase activity. In-SITU field and culture nutrient manipulatiions were done to determine if the addition of nitrogen stimulates alkaline phosphatase activity.
No spatial or temporal pattern occurred using the ELF-97 technique. The alkaline phosphatase assay showed a decrease over time. These results suggest that ELF-97 is not able to offer a complete idea of alkaline phosphatase activity due to the small size of some organisms who use the enzyme and the damage that filtering the samples causes may affect the count. A similarity in dominant species suggests that the species compisition of the site may influence the amount of alkaline phosphatase activity. The results also suggested that alkaline phosphatase activity may be a natural part of nutrient cycling rather than a sign of inorganic phosphorus stress. Additionally, it was determined that the addition of nitrogen stimulates alkaline phosphatase activity in both nitrogen limited and non-limited systems, although more nitrogen must be added to induce the activity in more stable environments.

Sonia Mae Johns will be studying the pelagic ecosytem in the San Juan Archipelago this fall at Friday Harbor before returning to Clarkson University to complete her undergraduate degree in biology and thesis on the effect of herbicides on the toxic cyanobacteria Microcystis sp. in Lake Champlain.  Following graduation, she plans to attend  graduate school to further prepare for a research career in oceanography.