| Often, in the eutrophied subtropical lagoonal Neuse River Estuary, a relatively large proportion of the total phytoplankton is located in a compact area, the chlorophyll a maximum (Cmax). This productive zone was investigated using bioassays to determine its response to nutrient pulses (nitrogen and phosphorus) and as a conduit of trophic transfer to mesozooplankton, especially copepods. The Cmax and nearby waters generally were nitrogen limited. Both nitrogen and phosphorus addition caused phytoplankton carbon to nutrient molar ratios to decrease accordingly when that nutrient was limiting and often when it was not. Nauplii were identified as potentially important NRE grazers. Phytoplankton elemental content was found to influence trophic transfer, with high nutritional quality phytoplankton necessary for, but not guaranteeing, copepod success. Both nitrogen and phosphorus enrichment influenced copepod growth and abundance. In the context of water quality, relationships between eutrophication, phytoplankton distribution, copepod food quality, and carbon and nutrient fate are discussed. |
