ASPECTS OF STRESS IN THE TROPICAL MARINE ENVIRONMENT
225
4
t o
6
0
10
20
30
Temperature- OC
FIG. 6. Excess of large or small temperature range species over predicted values in
relation to temperature.
distributed over the temperature scale. Figure 6 shows the deviations
of the observed from the predicted values, and there is an excess of
large tolerance ranges in the temperate regions with an excess of small
ranges in polar and tropical waters.
It can be objected that the reduction of range at the polar and
tropical end of the scale results from the lack of waters with more
"1
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W Cm
2
+
OJ
+
c
s 191 7 ~
I5 r
C
27,u 25g 23E z 21I
W Cm
2
+
OJ
c
+
s 191 7 ~
I5 T
0
5
10
15
20
25
30
Mean temperature - O C
I
5
10
15
20
25
30
Mean temperature - O C
Fro. 7. Relation of the mean temperature range of American ooastal mollusos to the
annual mean temperature of the localities where they occur.