102 



Dean F. Bumpus and E. Lowe Pierce 



Fig. 10. Distribution of surface temperature in ° C (upper), salinity in ^/oo (middle) and density (m) 

 (lower) on North Carolina Shelf, January 1954. Dash-dot line indicates track of ship. 



the species were found principally in the Florida Current. The increase in number of 

 species is evident as one proceeds offshore over the shelf into Florida Current water. 



Sagitta bipunctata. The distribution and abundance of this species was similar in the area covered 

 by spring {Caryn 64) and winter {Atlantis 196) cruises. S. bipunctata was collected in small numbers 

 at several of the stations beyond the continental shelf and in a few instances they ranged shoreward 

 about midway over the shelf (Tables I and II). With one exception (Station 5143) it was taken only 

 in water where salinity was greater than 35 -5° j^^. It therefore appears to be restricted in this region 

 to Florida Current water or water recently mixed with such water. Bigelow and Sears (1939) did 

 not find this species between Cape Cod and Chesapeake Bay. 



Sagitta enflata was taken in almost every plankton sample on both cruises (Fig. 12). It was the 

 most abundant chaetognath as well as the most widely distributed. The greatest concentrations were 

 found near the edge of the shelf where as many as 160 per ten cubic metres were recorded. That they 

 are sensitive to extreme conditions which are occasionally encountered in this area is borne out by 

 their absence in the winter cruise from the three inshore stations north of Cape Hatteras. Here in 

 water of less than 10° C and 32°/oo not a specimen was found. Moreover only one specimen was 

 present at the two inshore stations south of Hatteras, where the water had been derived from Virginian 

 Coastal water driven around the cape. 



