Papers in Marine Biology and Oceanography, Suppl. to vol. 3 of Deep-Sea Research, pp. 92-109. 



The hydrography and the distribution of chaetognaths over the 

 continental shelf off North Carolina 



By Dean F. BuMPUs*t 



Woods Hole Oceanographic Institution 



and 



E. Lowe Pierce 



Department of Biology, University of Florida 



Summary — Temperature, salinity and quantitative plankton data have been obtained from the 

 continental shelf area and Florida Current off North Carolina in May and June 1953 and January 

 1954. 



Two water types, Virginian Coastal water and Carolinian Coastal water, and one water mass, 

 Florida Current water, are identified. 



A breaching of the barrier at Hatteras between the two coastal water types was witnessed, and 

 Virginian Coastal water was driven south-westerly across Diamond Shoals into Raleigh Bay by a 

 north-east storm. The import of such an hydrographic event on the distribution of plankton is 

 discussed. 



The distribution of the chaetognaths in the area was investigated and their association with the 

 water type and water mass tabulated. Twelve species representing three genera were collected. All 

 of these are found in tropical and sub-tropical waters. Chaetognaths fail as satisfactory indicators 

 of the Virginian Coastal water intrusion into Raleigh Bay because of the absence, in our collection, 

 of characteristically Virginian types in the southern limits of that faunal subprovince. 



INTRODUCTION 



Prior to the efforts of Pierce (1953), who described the distribution of the chaetog- 

 naths over the continental shelf off North Carolina in relation to the hydrography 

 of the area, and Bumpus (1955), who considered the circulation of these waters, little 

 was known about the effect of the circulation system on the distribution of planktonic 

 elements of the flora and fauna in the Hatteras area. Parr (1933) noted in winter 

 a temperature barrier at Cape Hatteras corroborated by Bigelow (1933) and a fairly 

 large cold-water temperature zone southwest of Cape Hatteras. This temperature 

 barrier is well illustrated in the surface temperature charts of Fuglister (1947). 

 Bigelow and Sears (1935) pointed out the abrupt transition in salinity which occurs 

 at Cape Hatteras, occasioned by the wedge of pure oceanic water (>35*5%o) which 

 presses in close across the shelf in Raleigh Bay and entirely separates the shelf and 

 slope water bands to the north from the low coastal salinities farther south. The data 

 available at that time suggested that the situation exists throughout the year. 



The existence of a barrier at Cape Hatteras has been postulated in defining the 

 Carolinian and Virginian faunal subprovinces (Johnson, 1934). Many other zoologists 

 have separated the cold-water and warm- water fauna on the continental shelf at this 

 cape. Williams (1948, 1949), Sutcliffe (1950) and Pearse and Williams (1951) 



* Contribution No. 760 from the Woods Hole Oceanographic Institution. 



t Part of this research was sponsored by the Office of Naval Research under contract No. 27701. 



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