WAMSI 2 - Dredging Node - Project 4.7 - Defining Thresholds and Indicators of Coral Response to Dredging Related Pressures - CORAL DEMOGRAPHY, Western Australia

An understanding of coral population dynamics (demography) is needed when designing and evaluating studies that aim to detect the effects of natural and anthropogenic mediated impacts on coral communities, and in particular when making predictions about the likelihood of and speed of recovery from such impacts. This study was undertaken to gather baseline data on demographic processes to improve our understanding of the fundamental population dynamics in relation to recruitment, growth and survival of reef building corals in the Pilbara. Measurements of key demographic processes were carried out annually over two years (April 2014 and March 2015) at Enderby and West Lewis Islands in the Dampier Archipelago, Western Australia. Locations sampled at Dampier Archipelago (where coral populations existed) were relatively unimpacted by bleaching mortality that occurred between 2011-2014. At each location permanent transects were established sufficient to provide up to several hundred tagged colonies in order to derive valid demographic rates (growth, mortality, shrinkage, fragmentation) for individuals of each size class, as well as to allow estimates of recruitment. Censuses were conducted using a combination of wide angle photographs of the permanent transects, detailed field censuses of recruits and adult corals, and direct measurements of tagged colonies. The corals investigated in this study were Acropora millepora, Turbinaria mesenterina and massive Porites spp. (mainly P. lobata and P. lutea). These species were chosen because they were among the most common coral taxa on reefs of the Pilbara, and on many reefs globally, making them fundamental to reef primary productivity and carbonate accretion, and because they have contrasting life histories and susceptibilities to disturbances.

在设计与评估旨在探测自然及人为介导扰动对珊瑚群落影响的研究，尤其是预测此类扰动后珊瑚群落恢复概率与恢复速率时，亟需掌握珊瑚种群动态（种群统计学，demography）相关知识。本研究旨在收集种群统计学相关的基础数据，以深化对皮尔巴拉（Pilbara）海域造礁珊瑚的补充、生长与存活相关的核心种群动态的理解。研究于西澳大利亚州丹皮尔群岛（Dampier Archipelago）的恩德比岛与西刘易斯岛开展，在两年时间内（2014年4月与2015年3月）每年对关键种群统计学过程进行测定。丹皮尔群岛内存在珊瑚种群的采样点位，相对未受2011-2014年间发生的白化死亡事件影响。各点位均设置了永久样带，可容纳最多数百个标记珊瑚群体，以便获取各尺寸等级个体的有效种群统计学参数（生长、死亡、萎缩、断裂），同时亦可用于补充率估算。普查工作结合了永久样带的广角摄影、幼体与成体珊瑚的野外详细普查，以及标记珊瑚群体的直接测量三种方式开展。本研究涉及的珊瑚物种包括千孔鹿角珊瑚（Acropora millepora）、叶状轮轴珊瑚（Turbinaria mesenterina）以及块状滨珊瑚属物种（Porites spp.，主要为团块滨珊瑚P. lobata与黄色滨珊瑚P. lutea）。选择上述物种的原因在于：它们既是皮尔巴拉海域乃至全球多数珊瑚礁中最常见的珊瑚类群之一，对珊瑚礁初级生产力与碳酸盐沉积具有核心支撑作用；同时它们的生活史特征与扰动敏感性存在显著差异。