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The article focuses on the study that examines how environmental factors drive the distribution of Symbiodinium genotypes. It cites that researchers use time series environmental data in the sampling set of coral hosts across multiple spatial scales and among multiple regions. They surveyed bleaching-susceptible corals in the genus of Acropora which is known as a component of Pacific reefs with species hosting Clades C and D. The researchers assayed clade membership for symbionts of Acropora hyacinthus and Acropora cytherea from American Samoa, Fiji, Philippines, and Palmyra Atoll. Based on the distribution patterns, they conclude that maximum habitat temperatures can drive local scale adaptation of symbiont populations, while other processes can dominate at the regional area.

Corals associate with a diverse community of prokaryotic symbionts that provide nutrition, antioxidants and other protective compounds to their host. However, the influence of microbes on coral thermotolerance remains understudied. Here, we examined the prokaryotic microbial communities associated with colonies of Acropora cf. tenuis that exhibit high or low thermotolerance upon exposure to 33°C (heated) relative to 29°C (control). Using 16S rRNA sequencing, we show that the microbial community structure of all A. cf. tenuis colonies was similar to each other at control temperature. Thermotolerant colonies, however, had relatively greater abundance of Endozoicomonas, Arcobacter, Bifidobacterium and Lactobacillus. At elevated temperature, only thermosensitive colonies showed a distinct shift in their microbiome, with an increase in Flavobacteriales, Rhodobacteraceae and Vibrio, accompanying a marked bleaching response. Functional prediction indicated that prokaryotic communities associated with thermotolerant corals were enriched for genes related to metabolism, while microbiomes of thermosensitive colonies were enriched for cell motility and antibiotic compound synthesis. These differences may contribute to the variable performance of thermotolerant and thermosensitive corals under thermal stress. Identification of microbial taxa correlated with thermotolerance provides insights into beneficial bacterial groups that could be used for microbiome engineering to support reef health in a changing climate., (© 2025 John Wiley & Sons Ltd.)

Corals exhibit different responses to increasing temperature but it remains unclear whether this is determined exclusively by symbiont type or by intrinsic properties of the host. Here, we investigated the response to elevated temperature of symbionts of the same ITS2 type from three acroporid species from Bolinao, northwestern Philippines. Maximum quantum yield (Fv/Fm) of PSII was measured in symbionts subjected to 26°C (average winter temperature) and 31°C (average summer temperature) for up to 48 hrs. Greater reduction in Fv/Fm was observed for ex hospite than for in hospite symbionts. However, no significant differences in response could be discerned for symbionts associated with or originating from the different acroporids. Thus, while these findings confirm that the coral host can protect in hospite symbionts from temperature perturbations, for the acroporids in this study, there is still no evidence that host type confers differential thermal susceptibility to the symbionts or to the coral holobiont. [ABSTRACT FROM AUTHOR]