134 U.S. NATIONAL MUSEUM BULLETIN 291 



The isopycnic distributions closely parallel the isohalines on the 

 section (fio:. 38) . The si^ma-t value of 27.75 nearly parallels the 34.70%o 

 isohaline from 50° to 160°W. Water of high density from the Ross and 

 Weddell Seas is evident in the western and eastern regions of the sec- 

 tion. The oxygen content of waters between 20°W and 50°W is very 

 high with minimum values ranging from 4.63 ml/L to 5.18 ml/L (fig. 

 37). The oxygen minimum layer lies between 1000 and 1600 m; a 

 shallow layer of minimum oxygen concentration in this area is located 

 at 200-250 m. At 65°W the oxygen minimum of -i.Ol ml/L is at 1250 m ; 

 westward the oxygen minimum values gradually increase and the 

 depths at which they are found decrease until at 145 °W the minimum 

 of 4.4 ml/L is located at 300 m. By 160°W the oxygen values are again 

 low, about 4.06 ml/L at 650 m. The same value at 65°W lies at 1600 m. 

 Isopleths of oxygen concentrations ascend to shallow depths in the 

 areas influenced by the outflow of the Weddell and Ross Seas. 



The vertical sections along 60°S complement the meridional sections 

 and give a broad picture of oceanographic features. The captures that 

 have been plotted on the 60°S sections come from that latitude and 

 from latitudes 2° to 3° north and south if a similar arrangement of iso- 

 therms exists at the proper depths. For example, if a capture were made 

 at 57°S 100°W in 2000 m between the 1.5° and 2° C isotherms it would 

 be plotted because the same conditions exist on the 60°S section. The 

 points of capture on the temperature section are concentrated between 

 the 1.5° and 2.5° isotherms. All points at less than 1000 m represent 

 juvenile or larval specimens. The shallowest points at 110°W remain 

 in a cold water tongue that passes northward between two cores of 

 warmer water. In relation with salinity the points of captures are gen- 

 erally associated with the layer of hi^^h salinity above 34.70%o ; all ex- 

 cept a few shallow specimens occur in salinities greater than 34.60%o. 

 Distribution of captures with density follow sigma-t values greater 

 than 27.50, mostly 27.75 to 27.82. The plots of captures generally 

 follow the oxygen minimum layer or deeper; only a few specimens 

 are above the zone of minimum oxygen. 



Summary of Distribution With Oceanographic Parameters 



Since captures from areas as broad as 25° of longitude are plotted 

 on each vertical section and since there is appreciable variation in the 

 distribution of oceanographic parameters with locality, it is necessary 

 to bring together the data presented in the vertical sections. The infor- 

 mation is summarized using the simultaneous or in situ oceanographic 

 data taken at the oceanographic station closest in time and space to 

 each biological station. 



