Recovery of a reef fish assemblage following hermatypic coral destruction by Acanthaster planci infestation

1993年10月和1994年10月，在日本琉球群岛之一的伊洛莫特岛的Amitori和Sakiyama海湾，研究了珊瑚礁鱼类群落结构的变化以及食珊瑚海星Acanthaster planci造成的严重死亡后纹状珊瑚的恢复。在Amitori Bay，1981至1982年间，鹿角珊瑚被A.planci完全杀死。死亡的珊瑚树枝已经显著退化，到1993年，一片平坦的低浮雕珊瑚碎石仍留在平原上。这个珊瑚礁被称为“死珊瑚礁”。然而，海湾一些地区的珊瑚自1988年以来已经恢复，珊瑚礁上活的鹿角珊瑚的平均表面覆盖率在1993年和1994年分别为81%和94%。这块珊瑚礁分别被称为“81%恢复珊瑚礁”和“94%恢复珊瑚礁”。另一方面，樱山湾珊瑚礁上的珊瑚没有被海星侵扰，因此两年珊瑚礁上的活珊瑚覆盖率都超过了95%。每年在活的、死的和恢复的珊瑚礁上建立了5个长20米、宽1米的断面。通过直接观察法对每个样带的鱼类进行计数，无结构死礁的平均鱼种数和平均个体数显著减少，与活体相比，回收率分别为81%和94%。生物礁和两种恢复礁之间的上述指标无显著差异。每年活珊瑚礁和恢复珊瑚礁之间的鱼类种类组成也相似。这些事实表明，恢复礁上鱼类群落的结构恢复到干扰前的状态，尽管活珊瑚覆盖率没有恢复到普朗西疫病爆发前的水平。

Changes in the structure of a reef fish assemblage along with recovery of hermatypic corals following heavy mortality by the coral-feeding starfish Acanthaster planci were investigated at Amitori and Sakiyama bays of Iriomote Island, one of the Ryukyu Islands of Japan, in October 1993 and 1994. At Amitori Bay, staghorn corals were completely killed with A.planci between 1981 and 1982. Dead coral branches had been strikingly degraded, and a flat plain of low-relief coral rubble remained by 1993. This reef is referred to as "dead coral reef." Corals of some areas at the bay, however, have recovered since 1988, and mean surface coverage of living staghorn corals on the reef was 81% in 1993 and 94% in 1994. This reef is referred to as "81% recovery coral reef" and "94% recovery coral reef, " respectively. Corals on the Sakiyama Bay reef, on the other hand, were not infested with the starfish, so living coral coverage on the reef was more than 95% in both years.Five transects 20 m long and 1 m wide were established on the living, dead, and recovery reefs each year. Fishes on each transect were counted by direct observation.The mean numbers of fish species and individuals per transect markedly decreased on the unstructured dead reef, compared with the living, 81% recovery, and 94% recovery reefs. These numbers showed no significant difference between the living reef and the 2 kinds of recovery reefs. Fish species composition also was similar between the living and recovery reefs each year. These facts suggest that the structure of the fish assemblage on the recovery reef returned to the predisturbance state, although living coral coverage did not recover the levels prior to the outbreak of A.planci.