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.