Characterization of a thermally tolerant Orbicella faveolata reef in Abaco, The Bahamas

Parker, Katherine E.; Ward, Jeremy O.; Eggleston, Erin M.; Fedorov, Evan; Parkinson, John Everett; Dahlgren, Craig P.; Cunning, Ross

doi:10.1007/s00338-020-01948-0

Cited by 20 publications

(12 citation statements)

References 71 publications

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“…Evidence from previous studies has been equivocal on the relative levels of variability between stressed and unstressed corals. High temperatures have been shown to drive community differences among colonies [ 98 , 99 ], but they can also result in increased stability [ 100 ], as our data here illustrate. These community patterns were accompanied by a decrease in Symbiodiniaceae richness from 14.1 types per normal colony and 9.4 types per bleaching colony during the 2016 bleaching event to just 7.8 types per colony after the event (2017–2018).…”

Section: Discussionsupporting

confidence: 64%

“…The long-term, frequent and focused monitoring of corals at the colony level [ 113 ], incorporating endosymbiont genotyping, would help resolve these questions. Because there are also species-specific effects associated with bleaching, recovery and endosymbiosis in general [ 98 , 114 ], a broad range of species spanning different levels of susceptibility and resilience [ 44 , 115 , 116 ] needs to be studied. Corals are also associated with a complex array of bacterial communities, and it has recently been shown that the dominant Symbiodiniaceae type is linked to particular bacterial abundances under specific disturbance regimes [ 19 ].…”

Section: Discussionmentioning

confidence: 99%

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Homogenization of Endosymbiont Communities Hosted by Equatorial Corals during the 2016 Mass Bleaching Event

et al. 2020

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Thermal stress drives the bleaching of reef corals, during which the endosymbiotic relationship between Symbiodiniaceae microalgae and the host breaks down. The endosymbiont communities are known to shift in response to environmental disturbances, but how they respond within and between colonies during and following bleaching events remains unclear. In 2016, a major global-scale bleaching event hit countless tropical reefs. Here, we investigate the relative abundances of Cladocopium LaJeunesse & H.J.Jeong, 2018 and Durusdinium LaJeunesse, 2018 within and among Pachyseris speciosa colonies in equatorial Singapore that are known to host both these Symbiodiniaceae clades. Bleached and unbleached tissues from bleaching colonies, as well as healthy colonies, during and following the bleaching event were sampled and analyzed for comparison. The nuclear ribosomal internal transcribed spacer (ITS) regions were separately amplified and quantified using a SYBR Green-based quantitative polymerase chain reaction (qPCR) method and Illumina high-throughput sequencing. We found Cladocopium to be highly abundant relative to Durusdinium. The relative abundance of Durusdinium, known to be thermally tolerant, was highest in post-bleaching healthy colonies, while bleached and unbleached tissues from bleaching colonies as well as tissue from healthy colonies during the event had depressed proportions of Durusdinium. Given the importance of Durusdinium for thermal tolerance and stress response, it is surprising that bleached tissue showed limited change over healthy tissue during the bleaching event. Moreover, colonies were invariably dominated by Cladocopium during bleaching, but a minority of colonies were Durusdinium-dominant during non-bleaching times. The detailed characterization of Symbiodiniaceae in specific colonies during stress and recovery will provide insights into this crucial symbiosis, with implications for their responses during major bleaching events.

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Section: Discussionsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Homogenization of Endosymbiont Communities Hosted by Equatorial Corals during the 2016 Mass Bleaching Event

et al. 2020

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“…Our experiment only included one O. faveolata colony hosting Breviolum , but our results agree with previous studies indicating higher thermotolerance of O. faveolata containing Durusdinium compared to Breviolum (e.g., Cunning et al 2015, 2018; Parker et al 2020). O. faveolata is remarkably flexible in its associations with Symbiodiniaceae and can host Symbiodinium, Breviolum, Cladocopium, Durusdinium , or a combination of all four of these genera (Rowan et al 1997; Kemp et al 2014; Kennedy et al 2016).…”

Section: Discussionsupporting

confidence: 90%

Variation in susceptibility among three Caribbean coral species and their algal symbionts indicates the threatened staghorn coral, Acropora cervicornis, is particularly susceptible to elevated nutrients and heat stress

Palacio-Castro

Dennison

Rosales

et al. 2021

Preprint

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Coral cover is declining worldwide due to multiple interacting threats. We compared the effects of elevated nutrients and temperature on three Caribbean corals: Acropora cervicornis, Orbicella faveolata, and Siderastrea siderea. Colonies hosting different algal types were exposed to either ambient nutrients (A), elevated NH4 (N), or elevated NH4 + PO4 (N+P) at control temperatures (26 °C) for > 2 months, followed by a 3-week thermal challenge (31.5 °C). A. cervicornis hosted Symbiodinium (S. fitti) and was highly susceptible to the combination of elevated nutrients and temperature. During heat stress, A. cervicornis pre-exposed to elevated nutrients experienced 84%-100% mortality and photochemical efficiency (Fv/Fm) declines of 41-50%. In comparison, no mortality and lower Fv/Fm declines (11-20%) occurred in A. cervicornis that were heat-stressed but not pre-exposed to nutrients. O. faveolata and S. siderea response to heat stress was determined by their algal symbiont community and was not affected by nutrients. O. faveolata predominantly hosted Durusdinium trenchii or Breviolum, but only corals hosting Breviolum were susceptible to heat, experiencing 100% mortality, regardless of nutrient treatment. S. siderea colonies predominantly hosted Cladocopium C1 (C. goreaui), Cladocopium C3, D. trenchii, or variable proportions of Cladocopium C1 and D. trenchii. This species was resilient to elevated nutrients and temperature, with no significant mortality in any of the treatments. However, during heat stress, S. siderea hosting Cladocopium C3 suffered higher reductions in Fv/Fm (41-56%) compared to S. siderea hosting Cladocopium C1 and D. trenchii (17-26% and 10-16%, respectively). These differences in holobiont susceptibility to elevated nutrients and heat may help explain historical declines in A. cervicornis starting decades earlier than other Caribbean corals. Our results suggest that tackling only warming temperatures may be insufficient to ensure the continued persistence of Caribbean corals, especially A. cervicornis. Reducing nutrient inputs to reefs may also be necessary for these iconic coral species to survive.

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“…This ITS2 type profile was driven by a background ITS2 variant 5231_C, which occurred at moderate frequencies (~7%) in the majority of S1 colonies but was mostly absent in colonies from other sites. This specificity to Cladocopium is a common and rather unique pattern across Western Australia 37,41,65,81 , in contrast to corals from other regions that show pronounced shifts in symbiont species composition across environmental gradients 62,64,82,83 .…”

Section: Resultsmentioning

confidence: 84%

Mechanisms of ecological divergence with gene flow in a reef-building coral on an isolated atoll in Western Australia

Thomas

Underwood

Rose

et al. 2021

Preprint

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Understanding the mechanisms driving phenotypic variation in traits facing intensified selection from climate change is a crucial step in developing effective conservation and restoration initiatives. This is particularly true for reef-building corals, which are among the most vulnerable to climate change and are in dramatic decline globally. At the Rowley Shoals in Western Australia, the prominent reef flat becomes exposed on low tide and the stagnant water in the shallow atoll lagoons heats up, creating a natural laboratory for characterising the mechanisms that control phenotypic responses to different environments. We combined whole genome re-sequencing, common garden heat stress experiments, transcriptome-wide gene expression analyses, and symbiont metabarcoding to explore the mechanisms that facilitate survival in contrasting habitat conditions. Our data show that, despite high gene flow between habitats, spatially varying selection drives subtle shifts in allele frequencies at hundreds of loci. These changes were concentrated into several islands of divergence spanning hundreds of SNPs that showed strong linkage disequilibrium and were associated with a coordinated increase in minor allele frequencies in corals taken from the lagoon habitat, where the range of environmental conditions is greatest. Common garden heat stress assays showed individuals from the lagoon exhibited higher bleaching resistance than colonies from the reef slope, and RNAseq identified pronounced physiological differences between the corals from the two habitats, primarily associated with molecular pathways including cell signalling, ion transport and metabolism. Despite the pronounced physioloigical and environmental differences between habitats, metabarcoding of the Symbiodiniaceae ITS2 region revealed all colonies to be associated exclusively with the genus Cladocopium, with no detectable differences between habitats. This study contributes to the growing number of studies documenting the complex mechanisms that facilitate coral survival in extreme environments, and showcases the utility of combining multiple sequencing techniques to unravel complex climate-related traits.

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Characterization of a thermally tolerant Orbicella faveolata reef in Abaco, The Bahamas

Cited by 20 publications

References 71 publications

Homogenization of Endosymbiont Communities Hosted by Equatorial Corals during the 2016 Mass Bleaching Event

Homogenization of Endosymbiont Communities Hosted by Equatorial Corals during the 2016 Mass Bleaching Event

Variation in susceptibility among three Caribbean coral species and their algal symbionts indicates the threatened staghorn coral, Acropora cervicornis, is particularly susceptible to elevated nutrients and heat stress

Mechanisms of ecological divergence with gene flow in a reef-building coral on an isolated atoll in Western Australia

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