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Primary productivity by phytoplankton : temporal, spatial and tidal variability in two North Carolina tidal creeks

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Virginia L. Johnson (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
Michael Mallin

Abstract: Tidal creeks along the Coastal Plain are subject to rapid increases in urbanization and the associated pollution can have profound effects on ecosystem processes. Temporal, spatial and tidal variability of one such process, phytoplankton primary productivity, was examined in two tidal creeks in southeastern North Carolina. Physical, chemical and biological data were used to assess the factors regulating phytoplankton productivity and the magnitude with which urbanization has affected ecosystem function within these systems. Annual phytoplankton productivity in un-canopied high tide waters was approximately 91 gC m-3 in Futch Creek and approximately 246 gC m-3 in Hewletts Creek. Elevated primary productivity corresponded with the summer chlorophyll a maxima in both creeks, but was significantly higher in the creek with greater watershed development, Hewletts Creek, during summer months. Spatial variability in primary productivity in Hewletts Creek indicated upper oligohaline to mesohaline reaches were characteristically more productive during summer months than lower euhaline creek areas. Although there were defined temporal trends in phytoplankton productivity in the lesser developed Futch Creek, spatial variability between creek reaches was not as pronounced. Primary productivity was generally higher at low tide when compared to high tide in both creeks. Decreased water column irradiance occurred periodically in the upper reaches of both creeks, especially following meteorological events. Nutrient concentrations in Hewletts Creek, especially ammonium and orthophosphate, were generally higher than in Futch Creek and were elevated at upstream sites and seasonally during summer months. Regression analyses indicated that 83% of the variability in phytoplankton primary production was explained by variations in temperature and phytoplankton biomass. The data suggest that the physical environmental forces of a dynamic tidal creek system govern basic seasonal, spatial and tidal patterns, but sediment and nutrient inputs from upland development could have a pronounced effect on the magnitude of a key ecosystem process, phytoplankton primary productivity. Comparative analysis indicates that volumetric phytoplankton productivity in local tidal creeks was on par or greater than other larger North Carolina estuaries. This suggests that tidal creeks should be valued as a coastal resource and management efforts should be implemented to preserve and possibly restore environmental integrity.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment of the Requirements for the Degree of Master of Science
Language: English
Date: 2009
Keywords
Freshwater ecology--North Carolina, Freshwater phytoplankton--North Carolina--Futch Creek, Freshwater phytoplankton--North Carolina--Hewletts Creek, Phytoplankton--North Carolina
Subjects
Freshwater phytoplankton -- North Carolina -- Futch Creek
Freshwater phytoplankton -- North Carolina -- Hewletts Creek
Freshwater ecology -- North Carolina
Phytoplankton -- North Carolina