Coral tumor-like growth anomalies induce an immune response and reduce fecundity

Coral growth anomalies (GAs) are chronic diseases that adversely affect organism health and fitness. We investigated immunity and fecundity within and among GA-affected and visually healthy control colonies of the reef-building coral Acropora hyacinthus. Compared to controls, GAs had higher activity of the key immunity enzyme phenoloxidase (PO), suggesting a localised immune response within the GA. Both GAs and healthy tissue of GA-affected colonies had significantly greater total potential PO (tpPO)-PO activity inclusive of the activated latent PO, prophenoloxidase - than control colonies. Higher tpPO activity in GA-affected corals suggests elevated constitutive immunity compared to visually healthy controls. Additionally, fewer GA-affected colonies produced gametes, fewer polyps had oocytes (p < 0.001) and the number of oocytes per polyp was lower. Therefore, GAs in A. hyacinthus might induce, or represent a shift in resource investment towards immunity and away from reproduction. While the effect on population growth is likely to be small, reduced fecundity in GA-affected colonies does suggest a selective pressure against GAs

Coral reproduction at Hall Bank, a high latitude coral assemblage in Western Australia

Research on coral reproduction has increased dramatically in recent times; however, there remain significant regions, in particular high latitude reefs, where research is limited. For example, the reproductive biology of species in the coral assemblage at Hall Bank, a high latitude site (32 degrees S) in southern Western Australia, remain unknown. Here, reproductive traits and the likely time of spawning for 12 of the approximately 16 species that occur at Hall Bank were established using histology between March 2009 and March 2011 at 7 discrete time points. Peak reproductive activity most likely occurs in February, as 7 of the 10 species sampled in this month had colonies with mature gametes. The sexuality, mode of larval development and transmission of symbionts were, as expected, consistent with previous work. The reproductive biology of the corals at Hall Bank is consistent with other regions of the Indo-Pacific, supporting the hypo thesis that reproductive traits such as sexuality and mode of larval development are evolutionarily conserved and do not vary biogeographically

Synthesizing Larval Competence Dynamics and Reef-Scale Retention Reveals a High Potential for Self-recruitment in Corals

Many organisms have a complex life-cycle in which dispersal occurs at the propagule stage. For marine environments, there is growing evidence that high levels of recruitment back to the natal population (self-recruitment) are common in many marine organisms. For fish, swimming behavior is frequently invoked as a key mechanism allowing high self-recruitment. For organisms with weak-swimming larvae, such as many marine invertebrates, the mechanisms behind self-recruitment are less clear. Here, we assessed whether the combination of passive retention of larvae due to re-circulation processes near reefs, and the dynamics of settlement competence, can produce the high levels of self-recruitment previously estimated by population genetic studies for reef-building corals. Additionally, we investigated whether time to motility, which is more readily measurable than competence parameters, can explain the between-species variation in self-recruitment. We measured the larval competence dynamics of broadcast-spawning and brooding corals and incorporated these in a model of larval retention around reefs to estimate the potential for self-recruitment and assess its variation among species and reefs. Our results suggest that the larvae of many corals, even those with an obligate planktonic phase, develop with sufficient rapidity to allow high levels of self-recruitment, particularly for reefs with long water retention times. Time to motility explained 77–86% of the between-species variation in potential self-recruitment in scenarios with a realistic range of retention times. Among broadcast spawners, time to motility was strongly and positively correlated with egg size, i.e., broadcast spawner species with small eggs developed more rapidly and exhibited greater potential for self-recruitment. These findings suggest that, along with water retention estimates, easy-to-measure species traits, such as egg size and time to motility, may be good predictors of potential self-recruitment, and therefore may be used to characterize the spectrum of self-recruitment in corals

Cyphastrea salae, a new species of hard coral from Lord Howe Island, Australia (Scleractinia, Merulinidae)

A new zooxanthellate reef-dwelling scleractinian coral species, Cyphastrea salae sp. n. (Scleractinia, Merulinidae), is described from Lord Howe Island Australia. The new species can be distinguished morphologically from the only other congeneric species on Lord Howe Island, C. microphthalma, by the number of primary septa (12 vs. 10) and the much taller corallites (mean +/- SE: 1.0 +/- 0.07 mm v 0.4 +/- 0.04 mm). The relationship of C. salae to four of the other eleven currently accepted species in the genus was explored through analyses of nuclear (28S rDNA) and mitochondrial (noncoding intergenic region) gene sequences. Cyphastrea salae sp. n. forms a strongly supported clade that is distinct from a clade containing three species found commonly in Australia, C. chalcidicum, C. serailia, and C. microphthalma. One specimen was also found in the Solitary Islands, another high latitude location in south-eastern Australia. The discovery of a new species in the genus Cyphastrea on high latitude reefs in south-eastern Australia suggests that other new species might be found among more diverse genera represented here and that the scleractinian fauna of these isolated locations is more distinct than previously recognised

Bleaching susceptibility and mortality among corals with differing growth forms

Differences in bleaching susceptibility and mortality are apparent among coral species, and have been variously ascribed to differences in physiology and morphology, in particular overall growth form (e.g., branching versus massive corals). However, coral morphology is highly confounded with taxonomy, and no studies have tested for differences in bleaching susceptibility among corals with varying morphology within (rather than between) coral families. For this study, data were compiled for bleaching susceptibility and mortality from 65 published studies that monitored coral health throughout the bleaching event. Overall patterns of bleaching susceptibility were significantly different among coral growth forms, whereby a much higher proportion of branching, tabular, and submassive corals bleached compared to encrusting, massive, and free-living corals. However, differences in bleaching susceptibility and mortality were not consistent among growth forms within families. Branching faviid species (e.g., Echinopora) had much lower incidence of bleaching compared to massive species, but the reverse was true for Acroporidae and Poritidae. Moreover, mortality was markedly different amongst growth forms within families, such that massive Acroporidae (e.g. Montipora) suffered highest mortality when compared to Faviidae and Poritidae, but branching Acroporidae suffered lowest mortality compared to branching Faviidae and Poritidae. Our data suggest that generalities about the susceptibility of branching versus massive corals (and among other major growth forms) arise at least in part because certain growth forms are over-represented by highly susceptible coral taxa (e.g., Acropora) or perhaps because branching corals generally maintain higher dominance than massive corals

The shallow water hard corals of Pulau Weh, Aceh, Indonesia

The corals reefs of Aceh, Indonesia, are one of the few areas of the world where the fauna, in particular the scleractinian corals, have yet to be described. The area is likely to be of high biogeographical significance due to its position at the northern tip of Sumatra on the boundary of three major water bodies, the Indian Ocean, the Andaman Sea and the Straits of Malacca. Here, we present the quantitative description of the assemblage structure of the shallow water scleractinian corals of Pulau Weh. Carbonate reefs are rare on the island, the exception being some fringing reef development in shallow water in at least two locations. Most colonies are attached to granite boulders which make up the ocean floor at most sites on the north and west coast, or rest in the sandy substrates that dominate the ocean floor on the east coast. Coral cover in February 2009 was over 40 % at most sites, ranging from 21 % ± 3.0 SE to 80 % ± 2.4. Coral assemblage structure varied widely around Pulau Weh with assemblages from the western and northern sites being dominated by Acropora spp. in particular, species with digitate, encrusting-arborescent and tabular morphologies. In contrast, coral assemblages on the west coast were dominated by massive Porites spp. and Heliopora. The Acropora fauna is dominated by species with digitate and encrusting arborescent morphologies; very different from many other regions in Indonesia. This unusual species composition plus the presence of a high proportion of endemics indicates that the region should be a high priority for conservation efforts. Further taxonomic studies at depth and further afield are required to fully describe this unique fauna that supports a small diving industry and a number of fisheries

Cyphastrea kausti sp n. (Cnidaria, Anthozoa, Scleractinia), a new species of reef coral from the Red Sea

A new scleractinian coral species, Cyphastrea kausti sp. n., is described from 13 specimens from the Red Sea. It is characterised by the presence of eight primary septa, unlike the other species of the genus, which have six, ten or 12 primary septa. The new species has morphological affinities with Cyphastrea microphthalma, from which it can be distinguished by the lower number of septa (on average eight instead of ten), and smaller calices and corallites. This species was observed in the northern and central Red Sea and appears to be absent from the southern Red Sea

Allometric growth in reef-building corals

Funding: ARC Centre of Excellence for Coral Reef Studies and the Australian Research Council for fellowship and research support; Scottish Funding Council (MASTS, grant reference HR09011) and the ERC project bioTIME.Predicting demographic rates is a critical part of forecasting the future of ecosystems under global change. Here, we test if growth rates can be predicted from morphological traits for a highly diverse group of colonial symbiotic organisms: scleractinian corals. We ask whether growth is isometric or allometric among corals, and whether most variation in coral growth rates occurs at the level of the species or morphological group. We estimate growth as change in planar area for 11 species, across five morphological groups and over 5 years. We show that coral growth rates are best predicted from colony size and morphology rather than species. Coral size follows a power scaling law with a constant exponent of 0.91. Despite being colonial organisms, corals have consistent allometric scaling in growth. This consistency simplifies the task of projecting community responses to disturbance and climate change.PostprintPeer reviewe

Scope for latitudinal extension of reef corals is species specific

In their recent paper, Muir et al. (Science, 2015, 348, 1135-1138) demonstrate that the maximum depths of staghorn coral assemblages are shallower at higher latitudes, a trend that correlates with winter light levels. Based on these findings, the authors hypothesize that light availability limits the current latitudinal extent of the group and will constrain future range expansion. Here we reanalyze their data and show that depth-latitude relationships vary substantially among species, and that most species show either no significant pattern or the opposite pattern. In so doing, our reanalysis highlights a common misinterpretation of mixed-effects models: the fallacy of the average. Our findings are also consistent with fossil and contemporary observations of coral range-shifts. The factors that limit the current range extent of corals remain elusive, but they are likely speciesspecific and will require much further research to elucidate

The arctic circle boundary and the Airy process

We prove that the, appropriately rescaled, boundary of the north polar region in the Aztec diamond converges to the Airy process. The proof uses certain determinantal point processes given by the extended Krawtchouk kernel. We also prove a version of Propp's conjecture concerning the structure of the tiling at the center of the Aztec diamond.Comment: Published at http://dx.doi.org/10.1214/009117904000000937 in the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org