96 Dean F. Bumpus and E. Lowe Pierce 



current is being maintained in Onslow Bay and southward, such water movements 

 may distribute planktonic elements of Virginian fauna for some distance along the 

 coast. 



We have postulated here a sporadic occurrence which may contribute appreciably 

 to the finding of anomalous species in the inshore waters of the northern part of the 

 Carolinian subprovince. These species will find themselves in waters compatible to 

 their existence until vernal warming traps them. Vernal warming or reduction in 

 runoff with a consequent increase in salinity w^ill kill those species least resistant to 

 higher temperatures and salinities. 



THE DISTRIBUTION OF TEMPERATURE, SALINITY AND DENSITY IN MAY AND 



JUNE, 1953, AND JANUARY, 1954 



Typical spring conditions were encountered on the May and June cruises (Figs. 1, 

 2, 3, 4 and 5). These are the weak cross-shelf temperature gradient, moderate vertical 

 temperature gradient, and the penetration across the shelf of highly saline Florida 

 Current water along the bottom into Raleigh and Onslow Bays. In contrast the 

 temperature and salinity in the Wimble Section are lower with weaker vertical tempera- 

 ture gradients and stronger salinity gradients. 



Typical winter conditions for the Wimble, Onslow and Long Bay sections were 

 observed in January 1954 (Figs. 1 , 6 to 10). Note the cold coastal water in the Wimble 

 section and the nearly as cold, highly saline water in Onslow Bay and Long Bay. But 

 Raleigh Bay was filled in its inner part with coastal water from north of Cape Hatteras, 

 in contrast to the typical winter conditions of January and February 1950 (Bumpus, 

 1955) and February 1931 (Bigelow and Sears, 1935), when the 36°/oo isohaline 

 (Florida Current water) was pressed well in across the continental shelf. This 

 anomalous condition was due to a north-east storm several days earlier. 



This intrusion of Virginian Coastal water into Raleigh Bay is further discerned in 

 the temperature-salinity relation (Fig. 11). The water at Stations 5141, 5142 and 5143 

 is clearly Virginian Coastal water. 



The temperature-salinity relations also provide a clue to the sources in the Florida 

 Current contributing to the composition of Carolinian Coastal water. The water 

 over the inner middle part of Long Bay (Stations 5149, 5150, 5151), Onslow Bay 

 (Stations 5134, 5135, 5136, 5146) and the southern part of Raleigh Bay (Station 5145) 

 in January appears to be from depths in the Florida Current, i.e. from depths perhaps 

 as great as 150 metres. This water has been forced up onto the shelf in the course of 

 current meanders and chilled by the colder air temperatures encountered there. 

 Stations 5133 in Onslow Bay and 5147 and 5148 in Long Bay, the closest inshore 

 stations, indicate appreciable dilution of this Florida Current water with river effluent 

 and greater chilling as a result of the colder air temperatures near the coast. In 

 contrast, the water over the outer parts of the shelf (Stations 5144 in Raleigh Bay, 

 5137, 5138 and 5139 in Onslow Bay and 5152, 5153, 5154 in Long Bay) is Florida 

 Current water which has moved in over the shelf with no change in depth and has 

 mixed only slightly with the water inshore of it. 



The intrusion of Florida Current water along the bottom in Onslow and Raleigh 

 Bays in May and June (Figs. 3, 4, 5 and 1 1) was probably along surfaces of equal 

 density. It has been forced onto the shelf by the meanders of the current as it passes 



