Coral recruitment of a subtropical coral community at Yenliao Bay, northern Taiwan

Abstract

Background: The subtropical coral community at Yenliao Bay (25° 3′ N, 121° 56′ E), northern Taiwan, is distinguished from tropical reefs by low species diversity, low coral cover, and limited reef-building activities. Coral recruitment in this community was hypothesized to be lower due to features of marginal environment. Results: We studied the seasonal variations of coral recruitment at Yenliao Bay from May 2006 to September 2009. Two groups of ceramic plates were deployed at three reefs with one group retrieved at 3-month intervals and the other at 1-year intervals. Coral recruits in Yenliao Bay were found only in summer and early autumn (from June to October) corresponding to the reproductive season of corals in this area. The taxonomic composition of coral recruits was dominated by Pocilloporidae (52% to 90%) and Acroporidae (10% to 41%). Recruitment rates varied greatly in four consecutive years, ranging from 8.0 ± 3.1 recruits m-2 (mean ± SE) in 2008 to 116.4 ± 42.4 recruits m-2 in 2006. The survival rate of coral recruits after 1 year was approximately 12%, and acroporid recruits had a higher survival rate. Most of the coral recruits settled on top and vertical surfaces in contrast to the preference of bottom surface in tropical reefs. Furthermore, there was a negative correlation between the number of recruits and depths. Conclusions: Coral recruitment at Yenliao Bay occurred in summer and early autumn. The high recruitment rates in 2006 and 2007 were comparable with those of tropical reefs, suggesting that recruitment might not be a limiting factor for the maintenance and development of local coral communities. The number of coral recruits on top and vertical surfaces was negatively correlated with depths, suggesting that light intensity is possibly the primary factor controlling settlement and survival of coral recruits in subtropical coral communities. © 2014 Ho and Dai; licensee Springer.