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X D a ta
survival respectively. Survival remained high (more than 90 %) at all pressures at 10
and 15°C (Fig. 3.17).
percentage
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5 o C
U 2 48 32
B ELA
10 o C
15 o C
20 o C
U 2 48 32 B ELA U 2 48 32 B ELA U 2 48 32 B ELA
200 atm 150 atm 100 atm 50 atm 1 atm
D evelopm ental Stage
Fig. 3.15. Marthasterias glacialis embryos incubated at 5, 10, 15 and 20° C at 1, 50,
100, 150 and 200 atm for 48 h. Histogram represent % mean and SD. Development
stages are (U) Uncleaved, 2 to 32 cell, (B) Blastula, (E) Early gastrula, (L) Late
gastrula and (A) Abnormal.
3.4- Discussion
Experimental work on the pressure and temperature tolerances of embryos and
larvae of shallow water echinoids suggest that they are capable of entering the deep
sea along isotherms, but across isobars. In the northern Mediterranean (Young et al.,
1997) embryos and larvae of the shallow water echinoids Paracentrotus lividus
(Lamarck), Arbacia lixula, and Sphaerechinus granularis tolerated pressures as high
as 150 atm at 15° C. Lower temperatures (