Coral recruits were sampled from 20 pre-conditioned, unglazed, terracotta tiles, deployed at each of four sites around Lizard Island in the Northern Great Barrier Reef (GBR), and four sites around Orpheus and Pelorus Islands in the Palm Islands group in the central GBR. Tiles were scattered haphazardly over an area approximately 100 m², at a depth of three to nine metres, and represented a total settlement surface area of 0.572 m². Tiles were recovered, sampled for coral recruits, cleaned and redeployed roughly every three months from May 2009 until May 2010 at Lizard Island sites, and every two months until May 2011 at Palm Islands sites. In February 2011, a category five tropical cyclone, TC Yasi, hit the Palm Islands and destroyed the windward sites (NE Orpheus and NE Pelorus). All tiles at these exposed sites were lost, thus the last sampling was in early December 2010.
Each census and sampling of coral recruits was done under a dissecting microscope by systematically scanning all sides and edges of each tile. Pocilloporid recruits were identified visually. Recruits sampled were photographed, snapped off tiles using a scalpel and stored in absolute ethanol until genetic processing.
DNA of coral recruits was extracted and samples were tested with a rapid genetic assay to distinguish Pocillopora damicornis from other pocilloporid recruits and to determine their respective lineage. Samples identified as Pocillopora damicornis Type alpha and beta were genotyped at nine microsatellite markers using the
multiplex groups, primers and protocols described in (Torda et al. 2013).
Measures of larval dispersal in two lineages of P. damicornis, Type alpha and beta (Schmidt-Roach et al. 2013) from the Great Barrier Reef were inferred by comparing microsatellite genotypes betweeb the recruits and adult populations on the GBR (Torda et al. in review: Revisiting the connectivity puzzle of the common coral Pocillopora damicornis). Individual-based population genetic statistics were used to compare genotypic data of recently settled coral recruits to those of adults in the same population, in order to overcome the issue of cumulative and multi-generational patterns of connectivity when adult populations are the only group considered.