Seasonality of asexual reproduction in Holothuria atra, Holothuria edulis and Stichopus chloronotus on the Great Barrier Reef

Asexual reproduction by fission was monitored in populations of Holothuria atra, Holothuria edulis and Stichopus chloronotus on 3 nearshore fringing reefs (Brook Island, Fantome Island and Great Palm Island) and one midshelf reef (Rib Reef) on the Great Barrier Reef between March 1995 and August 1996.Holothuria atra was monitored at Brook Island, Fantome Island, one site at Great Palm Island and Rib Reef at depths of 0.5-3 m. Stichopus chloronotus was monitored at 3 sites on Great Palm Island and at Rib Reef at depths of 0.5-3 m. Holothuria edulis, occurring at depths of 12-15 m, was monitored at one site on Great Palm Island. Monitoring of the shallow nearshore reef sites occurred every 4 to 8 weeks, while the deeper Holothuria edulis population and the populations at Rib Reef were monitored less frequently. Between 100 and 400 Holothuria atra and Stichopus chloronotus and a minimum of 60 Holothuria edulis were examined for external signs of asexual reproduction on each occasion. The number of intact individuals and recently divided specimens (with a fresh wound or with a healed wound and no regenerated anus or mouth) were recorded. Population density was estimated on one occasion at each site using belt transects between May and August 1995.In February 1995, 30 Holothuria atra, 20 Holothuria edulis and 45 Stichopus chloronotus were collected and maintained in outdoor aquaria and fission and spawning in these individuals was monitored throughout 1995. This study of Holothuria atra, Holothuria edulis and Stichopus chloronotus was undertaken to determine:1. the seasonality of asexual reproduction by fission2. spatial differences in fission frequency and3. the proportion of the populations reproducing by fission

1995年3月至1996年8月期间，研究团队于大堡礁的3座近岸岸礁（布鲁克岛、幻景岛、大棕榈岛）及1座陆架中部礁（里布礁）的种群中，对黑海参（Holothuria atra）、玉足海参（Holothuria edulis）和绿刺参（Stichopus chloronotus）的分裂生殖过程开展监测。
黑海参的监测点位设于布鲁克岛、幻景岛、大棕榈岛的1个站点，以及里布礁，监测水深为0.5~3米。
绿刺参的监测点位设于大棕榈岛的3个站点，以及里布礁，监测水深为0.5~3米。
玉足海参栖息于12~15米水深区域，其监测点位设于大棕榈岛的1个站点。
近岸浅水区礁体的监测频率为每4~8周一次，而深水区域的玉足海参种群及里布礁的海参种群监测频率较低。
每次监测时，研究人员均会检查100~400头黑海参与绿刺参，以及至少60头玉足海参的无性繁殖外部特征。
研究人员会记录完整个体以及近期完成分裂的个体（带有新鲜伤口，或伤口已愈合但尚未再生出肛门或口部）的数量。
1995年5月至8月，研究团队于各站点采用带状样带法开展了一次种群密度估算。
1995年2月，研究人员采集了30头黑海参、20头玉足海参及45头绿刺参，将其饲养于室外水族箱中，并于1995年全年监测这些个体的分裂生殖与产卵行为。
本项针对黑海参、玉足海参及绿刺参的研究旨在明确以下3项内容：1. 分裂生殖的季节周期性；2. 分裂生殖频率的空间差异；3. 种群中以分裂生殖方式繁殖的个体占比。