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.

Surveys of crown-of-thorns starfish (Acanthaster planci) were undertaken in the western half of the Dampier Archipelago, at 3 fringing reefs (Enderby Island, Goodwin Island and Kendrew Island) and 1 barrier reef (Sailfish Reef) in 1987.

The manta tow technique was used to record the relative abundance of crown-of-thorns starfish, numbers of white feeding scars on corals and estimates of live and dead hard coral cover. This technique was also used to identify suitable collection sites where Acanthaster planci was abundant.

Samples of Acanthaster planci were collected using scuba at 2 sites on each of Kendrew and Enderby Reefs, and at 1 site on Goodwyn and Sailfish Reefs. Crown-of-thorns starfish were collected from each of these sites, except for Goodwyn Reef, where no individuals were observed.

The diameter of each starfish was recorded and samples of pyloric caeca were taken. The labelled samples were stored in liquid nitrogen and returned to AIMS for genetic analysis. Photographs were taken of each starfish collected at Enderby Island (site 1), and then a portion of aboral disc and 2 arms removed from each. These samples were labelled, stored in 5% sea-water formalin and returned to AIMS for subsequent morphometric analysis. Observations were also made on gonad development and any damage sustained by the starfish.

The distribution of genetic variation of 7 microsatellite DNA markers in the mass-spawning coral Acropora tenuis was measured to infer patterns of connectivity among reef systems in the offshore (Scott Reef and Rowley Shoals) and coastal (Dampier Archipelago and Ningaloo Reef) zones of northwest Australia.Samples from 1156 colonies of Acropora tenuis were collected from 6 or 7 sites (more than 40 colonies were collected from most sites) at each of the Scott Reef, Rowley Shoals, Ningaloo Reef and the Dampier Archipelago systems.To minimize multiple collections of the same genet that may have been produced through asexual fragmentation or propagation (ramets), only a colony that was physically distinct and more than 1.5 m from other colonies was sampled. Note this provided an unbiased underestimate of the real contribution of asexual reproduction. Clonality was measured by calculating the proportion of unique multilocus genotypes as (Ng:N) at each site: of the 1156 samples collected, 1061 had unique multilocus genotypes.To explore the historical genetic connections among sites and systems, the amount of genetic variation were analysed within and among sites with respect to different alleles (FST), and on the sum of squared size differences of the alleles, assuming a stepwise model of mutation (RST).To further quantify the relationships among sites, 3 genetic distance measures between pairs of sites were calculated: DLR, which compares the likelihoods of complete multilocus genotypes in two populations; DS, Nei's standard genetic distance; and pairwise FST.Genetic diversity measures were calculated with FSTAT v2.9.3 as an unbiased estimate of gene diversity (HSK) and allelic richness (RS) per locus and site. The loci names use a prefix for the species followed by 2 or 5 according to the repeat motif type (di- or pentamer), followed by a number: Amil2-006, Amil2-010, Amil2-011, Amil2-012, Amil2-018, Amil2-022, Amil5-028. To assess genetic structure and diversity using 7 DNA microsatellite loci of the mass-spawning hard coral, Acropora tenuis, from a series of isolated and discontinuous coastal and offshore reef systems in northwest Australia.To test whether genetic and genotypic (clonal) diversities vary between the high-latitude, offshore reefs and the low latitude, coastal reefs.To gain further insight into degree of isolation, effective population size and the importance of asexual versus sexual reproduction.