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Percentage of individuals swimming after 24 h
1 1 0
1 0 0
9 0
8 0
7 0
6 0
1 1 0
1 0 0
9 0
8 0
7 0
6 0
1 1 0
1 0 0
9 0
8 0
7 0
6 0
1 1 0
1 0 0
9 0
8 0
5 o C
1 0 o C
1 5 o C
7 0
6 0
2 0 o C
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0
P
r e s s u r e i n a t m
Fig. 3.16. Asterias rubens survival of swimming bipinnaria at 5, 10, 15 and 20° C at
1, 50, 100, 150 and 200 atm for 24 h. Data are mean and SD of 3 replicates.
Embryos of the lower bathyal species E. affinis were truly barophilic (Young
et al., 1993). These data support the hypothesis (Kussakin, 1973; Menzies et al.,
1973) that the deep sea could have been invaded during or since the last ice age by
larvae capable of tolerating lower temperatures and greater pressures.
In the present study, early embryos of Asterias rubens were able to tolerate
pressures up to 150 atm at 15 o C and 100 atm at 10 o C and embryos of Marthasterias
glacialis were able to tolerate pressures up to 150 atm at 15 and 20 o C and up to 100
atm at 10 o C. At the lowest temperatures (5 o C) there was abnormal embryonic
development at 1 and 50 atm, whilst at 100 and 150 atm the development just delayed.
Although survivorship of early embryos was variable with temperature and pressure,
the survivorship of swimming bipinnaria at all temperature and pressures remained
effectively high (> 70 %).
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