BATHYPELAGIC SQUID BATHYTEUTHIS 111 



protrudes to beyond 60°S at 300-500 m then descends northward and 

 ends against the Falkland Else at 2400 m. Below the 2° isotherm the 

 water cools gradually toward the bottom. 



The salinity section also shows the influence of the Falkland Cur- 

 rent in the subantarctic region (fig. 26). The isohalines that originate 

 near the surface in 59°-61°S descend northward and meet the Falk- 

 land Rise at increasing depths. The 34.60%o isohaline runs at a diagonal 

 from near the surface at 61°S to 1700 m against the Falkland Rise. 

 The high-salinity core typical of Antarctic Circumpolar Water is 

 present as a large segment of 34.72%o that occupies the layer between 

 500 and 1500 m at 60°30'S and between 2200 and 2800 m at about 55° 

 to 57°S. In this region there can be no entry of Deep Water directly 

 from the north because of the broad expanse of the Patagonian conti- 

 nental shelf off eastern South America. A small tongue or core of 

 higher salinity water up to 34.74%o occurs in 600-1500 m at 59°-61°S. 

 The density of the water in the 55 °W section remains low to con- 

 siderable depths particularly along the northern edge of the section 

 (fig. 26) . Sigma-t values of 27.75 are encountered on the bottom at 2500 

 m in the north at 55°S, while the same density is found at 350 m at 

 60°30'S. Higher densities occur in association with the salinity maxi- 

 mum layer and the diminishing temperatures. 



The isopleths for oxygen concentration descend steeply toward the 

 north in the major portion of the Antarctic Circumpolar Water mass 

 (fig. 25). The oxygen minimum of 4.22 ml/L lies between 300 and 400 

 m at 60°30'S. Northward the oxygen concentration decreases in value 

 and location of the minimum increases in depth. At about 56°40'S the 

 minimum value is 3.82 ml/L, and the layer of minimum values is 

 located between 1500 and 2000 m. 



The captures that are plotted on the sections were all made between 

 50° and 59°W during Cruise 6. Twenty 3-meter IKMT tows were 

 made in depths greater than 500 m and twelve of these were success- 

 ful in capturing B. ahysdcola. Most of the unsuccessful tows were 

 at depths of less than 1000 m north of the convergence zone where the 

 temperature is generally over 3° C. Six of the captures were made at 

 temperatures between about 1.5° and 2° C in depths between 1650 

 and 2440 m ; these six tows produced 39 specimens. The shallow cap- 

 tures plotted at about 57°30' and 58°S are shown in water that is 

 slightly warmer than the "simultaneous" temperature at time of cap- 

 ture. The two specimens at 914 m came from 1.94° C, and the one 

 specimen at 713 m came from 2.11° C. The three remaining captures 

 in the 2° to 2.5° C layer had simultaneous temperatures from 2.09'' 

 to 2.23° C ; 27 specimens were taken in these three tows. The plot at 

 60°11'S represents a single specimen that had a simultaneous temper- 

 ature of about 1.4° C, so it is plotted in water a little too cold. 



