PHYSICAL ENVIRONMENT 



87 



Table 12. Monthly surface temperature ranges of the krill in the four principal regions of its abundance, 

 the figures in italics indicating scarcity or great scarcity of certain developmental phases in the plankton, 

 the dashes where certain developmental phases do not, or virtually do not, exist, the asterisks where the 

 surface population is wintering among or under the polar pack 



Absolute temperature range 



Optimum temperature range 



Month 



Dec. 



Nov. 



Oct. 



Sept. 



Aug. 



July 



June 



April-May 



March 



Feb. 



Jan. 



Dec. 



Nov. 



Oct. 



Sept. 



Aug. 



July 



June 



April-May 



March 



Feb. 



Jan. 



Dec. 



Nov. 



Oct. 



Sept. 



Aug. 



July 



June 



April-May 



March 



Feb. 



Jan. 



Dec. 



Nov. 



Oct. 



Sept. 



Aug. 



July 



June 



April-May 



March 



Feb. 



Jan. 



Under 16 mm. 



{vast majority 



larvae) 



0-00 to +i'99 



— 2-00 to +i'99 



— 2-00 to +0-99 



— 2-00 to — o-oi 



— 2-00 to —O-OI 



0-00 to +2-99 

 + 2-00 to +3 '99 

 + 2-00 to +3 '99 

 + 1-00 to +3-99 



-2-00 to +0-99 

 -2-00 to —O-OI 



* 



* 



- I -GO to +0-99 



0-00 to + 0-99 



- 2-00 to 



- 2-00 to 



- 2-00 to 



- 2-00 to 



- 2-00 to 



- 2-00 to 

 -2-00 to 

 -2-00 to 

 -2-00 to 

 -2-00 to 



- 2-00 to 



-fO-99 

 + 0-99 

 + 0-99 



— O-OI 



— O-OI 



— O-OI 



-fo-99 

 -fI-99 

 +2-99 

 +2-99 

 + 1-99 



— 2-00 to — I -01 



* 



* 

 « 



* 

 * 



-2-00 to —O-OI 



— 2-00 to —O-OI 



— 2-00 to -O-OI 



— 2-00 to + 0-99 



16-20 mm. 

 (very young 

 adolescents) 



0-00 to +1*99 



— 2-00 to -fi-99 



— 2-00 to + 0-99 



— 2-00 to —O-OI 



Over 20 mm. 



[older adolescents 



and adults) 



South Georgia 

 0-00 to -f I -99 



— 2-00 to + 2-99 



— 2-00 to +0-99 



— 2-00 to —O-OI 



— 2-00 to —O-OI 



Under 16 mm. 



(vast majority 



larvae) 



+ 1-00 to +i-gg 



— 2-00 to —O-OI 



— 2-00 to — I -01 



— 2-00 to — I -01 



— 2-00 to — i-oi 



0-00 to + 2-99 

 + 1-00 to +3-99 

 + 1-00 to +3-99 



o-oo to +3-99 



0-00 to +0-99 

 + 2-00 to +3-gg 

 +2-00 to +3-gg 

 +2-00 to +3-gg 



— 2-00 to + 0-99 



— 2-00 to —O-OI 



« 



Bransfield Strait-\ 

 -2-00 to +0-99 



-2-00 to —O-OI 



* 

 * 



-2-00 to +o-gg 



-2-00 to —O-OI 



« 

 * 



* 



— —I -00 to —O-OI —I -00 to —O-OI 



— 0-00 to + 0-99 



— 0-00 to + 2-99 



Weddell drift 



-2-00 to +0-99 -2-ooto+o-99 — 1-00 to— 0-01 



-2-OOtO+0-99 -2-00 to -fo-99 — 2-OOtO— I-OI 



-2-00 to +0-99 —2-00 to +0-99 —2-00 to -I-OI 



-2-00 to —O-OI —2-00 to —O-OI —2-00 to -I-OI 



— —2-00 to —O-OI —2-00 to —O-OI 



—2-00 to —O-OI —2-00 to — O-OI 



— —2-00 to —O-OI —2-00 to +0-99 



— -2-00 to +0-99 -2-00 to +1-99 



— —2-00 to -4-1-99 —I -00 to -f2-99 



— —2-00 to -1-2-99 -I- I "00 to -f 1-99 

 •I -00 to -(-0-99 -2-00 to -f-I-99 -2-00 to -1-0-99 



East Wind driftf 



-2-00 to 



« 



■I-OI 



— 2-00 to — I-OI 



— 2-00 to -1-0-99 



— 2-00 to + 1-99 



— 2-00 to —O-OI 



* 



* 



— 2-00 to —O-OI 

 -2-00 to -f 1-99 



— 2-00 to -I- 1-99 



— 2-00 to -I- 1-99 



— 2-00 to — I-OI 



* 



• 



— 2-0O to — O-OI 



— 2-00 to —I-OI 

 -2-00 to -I-OI 



-J -00 to -1-0-99 



16-20 mm. 

 (very young 

 adolescents) 



0-00 to +i-gg 



— I -00 to —O-OI 



— 2-00 to — I-OI 

 -2-00 to — I-OI 



Over 20 mm. 



(older adolescents 



and adults) 



0-00 to -f 1-99 

 -I -00 to -I- 1-99 



— 2-00 to —O-OI 



— 2-00 to -O-OI 



— 2-00 to — I-OI 



0-00 to + 0-99 



-f 2-00 to -f 2-99 



-f I -00 to -f3-99 



+ i-oo to + 1-99 



0-00 to -f 0-99 



— I-oo to —O-OI 



* 

 * 



— I-oo to —O-OI 



0-00 to -1-2-99 



— I-OI to —O-OI —I-oo to — o-oi 



— 2-00 to — o-oi —I-oo to — o-oi 



— 2-00 to —I -01 — 2-OOtO —O-OI 



— 2-00 to —1-01 —2-00 to —1-01 



—2-00 to —1-01 



— —2-00 to —1-01 



— —2-00 to —1-01 



— —2-00 to +o-gg 



— — I-OO to -fo-99 



— —2-00 to -f 1-99 



— 1-00 to —0-01 -2-00 to -f 1-99 



— 2-00 to +o-gg 



— I-oo to —O-OI 



* 



* 



— 2-00 to 



# 



•I-OI 



— 2-00 to — I-OI 



— 2-00 to —I-OI 



— I-oo to +0-99 



— I-oo to —O-OI 



# 



* 

 # 



* 



* 



— 2-00 to — I-OI 



— 2-00 to —O-OI 



— 2-00 to -f 1-99 



— I -00 to -f I -99 



t Although both the Bransfield Strait and the East Wind drift are closed to navigation, the former from June to October, 

 the latter from June to about mid-December, it can be inferred from the observed situation at South Georgia and in the 

 Weddell drift that the 16-20 mm. group must in fact be absent from the plankton of both strait and East Wind zone from 

 June at least until August. 



