Physical oceanographic processes affecting larval transport around and through North Carolina inlets

Abstract

Atlantic Spot, Flounder, Croaker and Menhaden all spawn in shelf waters of North Carolina during late fall to early winter. The juveniles use estuaries such as Pamlico Sound and the Cape Fear River as nurseries during their first winter and spring. Previous studies of recruitment into the estuaries through barrier island inlets or estarine mouths assume that the pre and post metamorphosed larvae enter the estuaries at the bottom of the water column and move upstream thereafter. The mechanisms were presumed tidal. The Pamlico Sound has several inlets, Oregon, Hatteras and ocracroke, through which larvae can enter not only during flood stages of the tide but also in the presence of favorable oceanic to estuary sea level pressure gradients. The Cape Fear River has a strong semi-diurnal tidal flow both flood and ebb and also responds vigorously to one-sided divergences and convergences at its mouth. Flow, looking out of the mouth, is in at the left and out on the right. The conclusions are that, in addition to flooding tides, non-local forcing at the estuary mouths can effect transport of larval fish through the estuary mouths, throughout the entire water column.