Nutrient limitation dynamics of a coastal Cape Cod pond : seasonal trends in alkaline phosphatase activity
Haupert, Christie L.
MetadataShow full item record
LocationAshumet Pond, Cape Cod, MA
A bi-weekly seasonal study was conducted in Ashumet Pond (Cape Cod, Massachusetts). The Redfield Ratio (106C:16N:1P) and alkaline phosphatase activity (APA) were utilized in tandem as nutrient deficiency indicators (NDIs) for phytoplankton. The study objective was to evaluate the limiting nutrient status of the pond throughout the growing season. The development of a high throughput method for fluorometrically measuring APA allowed for a large quantity of pond-water samples to be analyzed. The new method utilized a cytofluor, a fluorescence multi-well plate reader, which increased sample throughput by 75% compared to a standard filter fluorometer method. The detection limit, capability to measure APA at different time intervals, and performance at sea were tested. APA measurements made using the cytofluor were comparable to those made using a standard filter fluorometer, thus indicating that the cytofluor is a suitable and preferred replacement to the fluorometer for APA measurements. The presence of alkaline phosphatase, an inducible phospho-hydrolytic enzyme, is commonly used as an NDI diagnostic for phosphate limitation. A nutrient enrichment incubation re-affirmed the use of APA as a robust indicator of phosphate limitation in phytoplankton. APA data indicate that the system experienced episodic periods of phosphate-deficiency, implying that the limiting nutrient regime was not static, but was changeable throughout the growing season. Seasonal trends in dissolved N:P and particulate C:P ratios often contradict the APA results, however, suggesting that the Redfield Ratio is an unreliable indicator of the overall nutrient limitation regime of the pond. The observed discrepancies between C:N:P and APA can be reconciled by taking into account seasonal changes in species composition, which played an important role in driving seasonal APA trends.
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution November 2000
Suggested CitationThesis: Haupert, Christie L., "Nutrient limitation dynamics of a coastal Cape Cod pond : seasonal trends in alkaline phosphatase activity", 2000-11-13, DOI:10.1575/1912/4131, https://hdl.handle.net/1912/4131
Showing items related by title, author, creator and subject.
Rintoul, Stephen R. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1988-03)Inverse methods are applied to historical hydrographic data to address two aspects of the general circulation of the Atlantic Ocean. The method allows conservation statements for mass and other properties, along with a ...
Mass, heat, oxygen and nutrient fluxes at 30°S and their implications for the Pacific-Indian through flow and the global heat budget Macdonald, Alison M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1991-07)Six hydrographic basinwide sections, two in each of the three major ocean basins, are employed in a set of inverse calculations to determine the extent of exchange between the Pacific and Indian Oceans through the ...
Oates, Roger Hunter (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2008-06)Biogeochemical cycling of phosphate is a key component in the overall production rate of coastal ecosystems. Mineral phases in the near-shore sediments play a significant role in the return of phosphate remineralized in ...