Summary

The South Atlantic Bight (SAB) extends along the east coast of the United States, from Cape Canaveral, FL to Cape Hatteras, NC. The shelf processes are mainly driven by nutrient rich water from river runoff, intrusion water driven from coastal upwelling and the Gulf Stream. Hence, the SAB is considered a natural laboratory because it provides a year round supply of phytoplankton and zooplankton by the intrusion water transported from the Gulf Stream. Consequently, these circulation patterns define the physical conditions in the SAB, which has a direct effect on the nutrient supply that impacts zooplankton communities. Productive waters can support large stocks of zooplankton; hence, it is expected that the zooplankton abundance will be a direct response to high concentrations of chlorophyll associated with intrusion water. In this study, we examined trends in taxonomic composition of these communities from 2015 to 2016, with and without the presence of intrusion water. Zooplankton samples were collected monthly at the 25m and 40m isobath along the Georgia-Florida portion of the SAB. Oblique tows were performed for quantitative zooplankton analyses using a conical net of 202µm mesh. Zooplankton species were morphologically identified to the lowest taxonomic level, and identity was confirmed with DNA barcoding targeting the CO1 gene. A total of 51 taxa were described for this study: belonging to different groups such as copepods, decapods, thaliceans and ichthyoplankton. Our study provides a detailed assessment of zooplankton diversity and abundance within the mid-shelf of the SAB.