Coral Reefs最新文献

Coral–algal interactions are pivotal in reef ecosystems globally as they can scale up ecosystem levels and lead to dominance shifts. In this study, we conducted a systematic review of global coral–algal interactions, identifying the most studied locations, species, and types of interactions. We then assessed how these interactions may be impacted by consumers and climate change. Over the past 20 years (2001–2020), coral and algae interactions were mostly explored in the Pacific, and the Caribbean and US East Coast, where branching and massive corals were the focus, while other coral growth forms received less attention, and effects on algae were often overlooked. Adult corals were generally reported to be damaged when directly interacting with algae through physical abrasion or allelopathy. Conversely, algae interactions were found to have a positive impact on juvenile corals by facilitating larval recruitment and settlement. As expected, coral–algal interactions and the type of coral–algal relationships vary globally, most likely due to differences in abiotic conditions, community composition and the number of studies performed in a region. Despite the large emphasis on the role of consumers in controlling coral–algal interactions, few studies directly explored the effects of herbivory on coral–algal interactions. Given the growing evidence that ocean warming and acidification can reduce the competitive ability of corals, understanding the dynamic relationships between coral, algae, and consumers under future climate change conditions is crucial in predicting future coral recruitment potential and reef composition patterns. Here, we highlight the main findings from coral–algal interaction studies performed in the last 20 year and point to future directions, such as: 1) diversifying location, coral species, growth forms and life phases; 2) considering effects on both sides of interaction, not neglecting effects on algae; and 3) taking a closer look into the role of consumers and microbiomes. Advancing our understanding of coral–algal interactions, as well as how these interactions shift under changing conditions, is critical in predicting how coral reef ecosystems may operate in the future.

Ocean acidification (OA) and ocean warming (OW) affect the calcification of corals, and intraspecific variations in response to these stressors in the population level need to be clarified for better future predictions. Using Acropora digitifera as our subject, we examined the intraspecific variability in calcification and maximum quantum yield (F_v/F_m) of photosystem II of symbiotic zooxanthella in responses to OA, OW, and OA + OW. Samples were taken from two different sites: Sesoko Station (warmer) and Sesoko South (cooler) in Okinawa, Japan. Calcification rates varied between the two sites, and noticeable differences were observed only among coral colonies from the Sesoko South site, specifically under control and OA treatments. Furthermore, F_v/F_m showed no variation between the sites due to those stresses. Hence, the calcification rates among A. digitifera colonies varied by habitat, and we found within-site variation only in the lower temperature location, Sesoko South. We observed diminished variation in response among colonies in the warmer site. The adapting to diverse environmental conditions and responding to changes such as seawater pCO₂ and temperature, may lead to differences in sensitivity between the two populations to OA, OW, and OA + OW. These intraspecific variation could arise from factors like acclimatizations, the influence of specific genotypes, or phenotypic plasticity of the colonies.

A key goal of coral restoration is to re-establish self-sustaining coral populations and ensure resilience to future stressors, which requires that genetic diversity is maximised. However, coral genetic and genotypic (clonal) diversity is variable across reef sites via success of sexual recruitment, and cryptic species diversity can complicate breeding efforts. Assessing genotypic and genetic diversity of colonies to be used in restoration is therefore critical to avoid founder, inbreeding or outbreeding effects. Considering recent efforts to upscale coral propagation on the Great Barrier Reef (GBR), we examined species, population and clonal structure of a commonly out-planted tabular Acropora species—Acropora hyacinthus (Dana, 1864). A total of 189 colonies were sampled from six reef systems throughout the northern-central GBR and genotyped using an Acropora-specific Affymetrix microarray, which resulted in 1387 variant sites that passed quality control. Cryptic species were readily resolved and all sampled A. hyacinthus colonies represented unique genotypes within sites at three reefs. At reefs that contained multi-ramet genets (clonal genotypes), the mean and maximum between-ramet distances were 0.68 and 1.99 m, respectively. Therefore, sampling colonies > 2 m apart increases the likelihood these colonies represent distinct genets. Such a sampling design therefore maximises genotypic diversity when sourcing colonies for propagation and out-planting. Based on these variant sites, we found no between-reef genetic divergence based on locality. Furthermore, through unintentional sampling of non-target tabular Acroporid species, we show how this genotyping method may be used for resolving taxonomic uncertainty as well as population dynamics.