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U.S. NATIONAL MUSEUM BULLETIN 291 



34.0 



I I i I 



11*1 



SOUTH PACIFIC 

 OCEAN 



28 (Tt ■ 



Figure 44. — T-S capture diagram of Bathyteuthis in the eastern South Pacific Ocean. In 

 Pacific Equatorial Water Bathyteuthis bacidifera is marked by "x" and B. abyssicola by 

 "a"; B. abyssicola in Intermediate Water is marked by a dot. 



the temperature is generally between 7° and 8° C ; four captures, in- 

 cluding the holotype of B. haddifera^ were made at 700-750 m close 

 to the 6° isotherm. All remaining captures were made in water colder 

 than 5° C, the majority between 4° to 5° C (fig. 46). Vertical sections 

 from the type locality of B. tacklifera are plotted in figure 49. Oxygen 

 concentrations in the eastern tropical Pacific are very low with mini- 

 mum values of less than 0.5 ml/L occurring in the upper layers. The 

 plot of captures against oxygen concentration (fig. 47) shows that the 

 two species occur below the minimum concentrations that range from 

 about 0.5 ml/L to 2.0 ml/L. The effect of these low concentrations is 

 discussed elsewhere. The distribution of the two species of Bothyten- 

 this in relation to phosphate concentration coincides with the region 

 of PO4 maximum (fig. 48). The plots all occur at concentrations 

 greater than 2.75 microgram atoms/liter. Phosphates are quickly 

 diminished in the upper waters where high productivity takes place. 



