SEXUAL REPRODUCTION OF THE TROPICAL SEA-CUCUMBER, ACTINOPYGA-MAURITIANA (ECHINODERMATA, HOLOTHUROIDEA), IN GUAM

The reproductive biology of the aspidochirote holothurian Actinopyga m auritiana was studied through 1988 and 1989. A gonadal index (gonad wt /drained body wt) was the best measure of reproductive readiness, reac hing peaks of up to 23% in spring and summer months, with peaks occurr ing at slightly different times in the 2-yr study Well developed oocyt es and sperm were present in many individuals from each sampling perio d. Spawned oocytes ranged from 110-135 mu m in diameter. Estimates of absolute fecundity ranged from 26.27 x 10(6) to 40.98 x 10(6) oocytes for gravid females, agreeing with data for this species in New Caledon ia. Reproductive periodicity, as correlated with ambient ocean tempera ture, was similar to the spring/summer spawning reported for this spec ies in New Caledonia, despite greater seasonal fluctuations in tempera ture and photoperiod at that location. This suggests that if temperatu re and/or photoperiod are important factors in reproductive timing, th ey work in an absolute (threshold) fashion rather than in a relative o ne. Temporal differences in reproductive peaks between years coincided with a La Nina event.