BATHYPELAGIC SQUID BATHYTEUTHIS 103 



present temperature, salinity, density (sigma-t) and oxygen values 

 from tlie surface to 3000 m. Details of the isotherms and isohalines 

 have not been plotted in the upper few hundred meters, because they 

 have no direct influence on the distribution of B. abyssicola. The loca- 

 tions of captures of B. ahyssicola have been plotted on the sections. 

 Each section will be discussed in relation to the oceanographic fea- 

 tures and the distribution of B. abyssicola. The location of the capture 

 points represents the most probable depth of capture by the open 

 Isaacs-Kidd Midwater Trawl. Specimens could have been captured 

 shallower or deeper, but the indicated depths are probably accurate 

 (see discussion and calculations of depth of capture). The values for 

 all plotted captures may not correspond exactly to the "simultaneous" 

 oceanographic values. Some variation with season may exist even at 

 depths below 500 m, especially in the convergence zone where the steep 

 isotherms may move north and south with seasonal changes. Also, many 

 captures were not made along the exact longitudes that are represented 

 in the sections. The locations of lines of equal values vary with longi- 

 tude, sometimes quite sharply. Therefore capture points have not been 

 plotted in cases where the "simultaneous" capture values vary signifi- 

 cantly from the values on the sections. 



25° West Longitude; 55° to 63° South Latitudes 



The sections from 25°W (figs. 21, 22) extend northward from the 

 northeastern part of the Weddell Sea and pass east of the South Sand- 

 wich Islands. The temperature section (fig. 21) locates the Antarctic 

 Convergence between 57° and 58 °S during the fall and early winter. 

 The influence of the frigid Weddell Sea water is evident in the entire 

 section. South of the convergence, the Surface Water is 0° C and below 

 f)3°S the water at all depths is around 0° C or colder; the 0° isotherm 

 lies at about 2400 m at 57°S and rises to 1500 m at 63°S. Water with 

 the character of Antarctic Bottom Water extends from these levels to 

 the l)ottom. The presence of the southward flowing Deep Water is 

 indicated by the 0.5° isotherm that rises steeply from below 2000 m at 

 54° S and forms a layer of "warm" water in the Antarctic Circumpolar 

 Water mass between 200 and 1000 m from 58° to 63°S. In other areas 

 around the Southern Ocean the corresponding isotherm at these levels 

 and latitudes is around 2.0° C, so the influence of the Weddell Sea is 

 apparent. The 1° isotherm rises steeply from below 1500 m at about 

 54° S to about 400 m at 57 °S, then it bends sharply northward under 

 the influence of the cold surface layer. A small core of 1° C water lies 

 between 59° and 60°30'S at 200-600 m. Water of 1.5° C occurs only 

 north of the convergence zone and is represented in the section by a 

 nearly vertical isotherm around 55°S. 



