Jump to main content.

Long Term Monitoring of Diagnostic Phytoplankton Photopigments to Assess Ecological Condition and Change in the Neuse River Estuary and Pamlico Sound, NC

Lexia M. Valdes, Michael F. Piehler and Hans W. Paerl

Institute of Marine Sciences, University of North Carolina-Chapel Hill, Morehead City, NC

Concentrations of phytoplankton diagnostic photopigments (chlorophylls and carotenoids) have been monitored in the Neuse River Estuary since 1994 and since 1999 in Pamlico Sound as part of the Neuse River Bloom Project, the Neuse River Estuary Modeling and Monitoring Study (ModMon) and the U.S. Environmental Protection Agency-Science to Achieve Results (USEPA-STAR) Atlantic Coast Environmental Indicators Consortium (ACE-INC). Photopigment concentrations were measured by HPLC and subsequently analyzed using the ChemTax matrix factorization program to determine the contribution of the five most common phytoplankton taxonomic groups found in these estuaries (chlorophytes, cryptophytes, cyanobacteria, diatoms and dinoflagellates) to total chlorophyll a. Phytoplankton are sensitive to changes in their environment, including anthropogenic (nutrient) and hydrologic (flushing rates, residence times) disturbances. Changes in their abundance and community composition can therefore be used to detect ecological condition and change in estuaries. Annual, seasonal and spatial trends in phytoplankton community structure were examined. Significant differences in the abundance of all five phytoplankton groups were observed between years, seasons and locations within the estuary. In addition, significant differences were detected between the abundance of the different taxonomic groups. We tested the hypothesis that these patterns were due to the hydrologic variability that was observed during the study period (droughts, tropical storms and hurricanes) that caused changes in water residence time and rates of nutrient loading.

Long term monitoring of phytoplankton photopigments is a broadly applicable tool. These data also provide valuable context for manipulative experiments that test the response of phytoplankton to changes in their environment.

Keywords: phytoplankton, photopigments, estuary, residence time, flushing, hurricanes, droughts, and ChemTax

EMAP Home | About EMAP | Components | Data | Documents | Bibliography | News | Site Map

Local Navigation

Jump to main content.