D. Stanwellsmith et Ls. Peck, TEMPERATURE AND EMBRYONIC-DEVELOPMENT IN RELATION TO SPAWNING AND FIELD OCCURRENCE OF LARVAE OF 3 ANTARCTIC ECHINODERMS, The Biological bulletin, 194(1), 1998, pp. 44-52
The effects of temperature on development and viability were measured
at 14 levels between -2 degrees C and + 3 degrees C on embryos of two
asteroids (Odontaster validus and Odontaster meridionalis) and an echi
noid (Sterechinus neumayeri) from Signy Island, Antarctica. Developmen
t rates were 2 to 10 times slower than those for temperate or tropical
echinoderms, with times to hatching up to 240 h. Development rates fo
r the two asteroids differed by 1.15 x, and rates for both species app
roximately doubled over the experimental temperature range. In O. vali
dus, embryo viability was independent of temperature, but in O. meridi
onalis viability declined with increasing temperature. Development rat
es for S. neumayeri were little affected by temperature above +0.2 deg
rees C, but declined rapidly at lower temperatures. Conversely, the nu
mber of nonviable eggs was low and constant below +1.7 degrees C, but
rose rapidly at higher temperatures. A window of optimal temperature,
between +0.2 degrees C and +1.7 degrees C, has therefore been proposed
for development time and embryo viability in this population of S. ne
umayeri. Spawning trials and field observations of larvae indicated th
at the time of gamete release and periods of larval development in S.
neumayeri coincided with austral summer sea temperatures in the same w
indow. Embryos of O. meridionalis and O. validus are released in winte
r, when temperatures are constantly below -1.6 degrees C. Comparison o
f the different strategies suggests that larval food supply and predat
ion during planktonic phases are not the dominant ecological factors f
or these species.