Multi-year, seasonal genotypic surveys of coral-algal symbioses reveal prevalent stability or post-bleaching reversion

Thornhill, Daniel J.; LaJeunesse, Todd C.; Kemp, Dustin W.; Fitt, William K.; Schmidt, Gregory W.

doi:10.1007/s00227-005-0114-2

Cited by 357 publications

(465 citation statements)

References 50 publications

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“…Although the adaptive bleaching hypothesis (ABH) has found support in a number of studies (19,21,44), increasing evidence now points toward a highly specific and persistent nature of established host-symbiont associations (24,(45)(46)(47). This is supported by our data whereby symbiont communities in S. pistillata were stable over two years despite minor fluctuations observed during bleaching.…”

Section: Discussionsupporting

confidence: 79%

“…Furthermore, in all but two colonies complete postbleaching reversion to the original symbiont type was observed. This occurred relatively rapidly compared with other studies (21,47) suggesting that shifts between closely related subcladal types are perhaps easier than between cladal types. Based on our data, it is difficult to determine whether the altered symbiont communities during bleaching originated from newly acquired symbionts or from background populations present within the host tissues.…”

Section: Discussionmentioning

confidence: 45%

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Bleaching susceptibility and mortality of corals are determined by fine-scale differences in symbiont type

Sampayo

Ridgway

Bongaerts

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

402

434

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Coral bleaching has been identified as one of the major contributors to coral reef decline, and the occurrence of different symbionts determined by broad genetic groupings (clades A-H) is commonly used to explain thermal responses of reef-building corals. By using Stylophora pistillata as a model, we monitored individual tagged colonies in situ over a two-year period and show that fine level genetic variability within clade C is correlated to differences in bleaching susceptibility. Based on denaturing gradient gel electrophoresis of the internal transcribed spacer region 2, visual bleaching assessments, symbiont densities, host protein, and pulse amplitude modulated fluorometry, we show that subcladal types C78 and C8/a are more thermally tolerant than C79 and C35/a, which suffered significant bleaching and postbleaching mortality. Although additional symbiont types were detected during bleaching in colonies harboring types C79 and C35/a, all colonies reverted back to their original symbionts postbleaching. Most importantly, the data propose that the differential mortality of hosts harboring thermally sensitive versus resistant symbionts rather than symbiont shuffling/switching within a single host is responsible for the observed symbiont composition changes of coral communities after bleaching. This study therefore highlights that the use of broad cladal designations may not be suitable to describe differences in bleaching susceptibility, and that differential mortality results in a loss of both symbiont and host genetic diversity and therefore represents an important mechanism in explaining how coral reef communities may respond to changing conditions. climate change ͉ coral reefs ͉ Symbiodinium ͉ zooxanthellae ͉ Stylophora

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 45%

Bleaching susceptibility and mortality of corals are determined by fine-scale differences in symbiont type

Sampayo

Ridgway

Bongaerts

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

402

434

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“…Symbiont replacement, when documented, often appears to be induced by physiological stress; for example, following transplantation to a new environment (Berkelmanns & van Oppen 2006; but see Thornhill et al 2006b). While novel combinations may be induced experimentally (Schoenberg & Trench 1980;Lewis & Coffroth 2004), there is little evidence that such processes readily occur naturally and/or are permanent.…”

Section: Discussionmentioning

confidence: 99%

Host–symbiont recombination versus natural selection in the response of coral–dinoflagellate symbioses to environmental disturbance

et al. 2010

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Mutualisms between reef-building corals and endosymbiotic dinoflagellates are particularly sensitive to environmental stress, yet the ecosystems they construct have endured major oscillations in global climate. During the winter of 2008, an extreme cold-water event occurred in the Gulf of California that bleached corals in the genus Pocillopora harbouring a thermally ‘sensitive’ symbiont, designated Symbiodinium C1b-c , while colonies possessing Symbiodinium D1 were mostly unaffected. Certain bleached colonies recovered quickly while others suffered partial or complete mortality. In most colonies, no appreciable change was observed in the identity of the original symbiont, indicating that these partnerships are stable. During the initial phases of recovery, a third species of symbiont B1 Aiptasia , genetically identical to that harboured by the invasive anemone, Aiptasia sp., grew opportunistically and was visible as light-yellow patches on the branch tips of several colonies. However, this symbiont did not persist and was displaced in all cases by C1b-c several months later. Colonies with D1 were abundant at inshore habitats along the continental eastern Pacific, where seasonal turbidity is high relative to offshore islands. Environmental conditions of the central and southern coasts of Mexico were not sufficient to explain the exclusivity of D1 Pocillopora in these regions. It is possible that mass mortalities associated with major thermal disturbances during the 1997–1998 El Niño Southern Oscillation eliminated C1b-c holobionts from these locations. The differential loss of Pocillopora holobionts in response to thermal stress suggests that natural selection on existing variation can cause rapid and significant shifts in the frequency of particular coral–algal partnerships. However, coral populations may take decades to recover following episodes of severe selection, thereby raising considerable uncertainty about the long-term viability of these communities.

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“…Due to 44 anthropogenic impacts, disease, and temperature-induced bleaching events, the 45 abundance of this prevalent species has declined by more than 80% in recent decades 46 The health of a coral colony is also tied to the identity and physiological qualities of 76 its dinoflagellate endosymbionts (Sampayo et al 2008). Mature A. cervicornis colonies 77 are typically found to associate with just one Symbiodinium species (S. 'fitti' = ITS2 type 78 A3 Caribbean ) at depths above ten meters (Thornhill et al 2006 expression biomarkers (GEBs), which capture dynamic stress responses, are promising 90 tools for coral restoration (reviewed by Louis et al 2016). By characterizing the 91 molecular profiles that correspond to stress-tolerance and stress-sensitivity, it is possible 92 to monitor the health of reef organisms, assess acute anthropogenic impacts (e.g.…”

Section: Introduction 42mentioning

confidence: 99%

Extensive transcriptional variation poses a challenge to thermal stress biomarker development for endangered corals

Parkinson

Bartels

Devlin-Durante

et al. 2018

Preprint

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As climate changes, sea surface temperature anomalies that negatively impact coral reef organisms continue to increase in frequency and intensity. Yet, despite widespread coral mortality, genetic diversity remains high even in those coral species listed as threatened. While this is good news in many ways it presents a challenge for the development of biomarkers that can identify resilient or vulnerable genotypes. Taking advantage of three coral restoration nurseries in Florida that serve as long-term common garden experiments, we exposed over thirty genetically distinct Acropora cervicornis colonies to hot and cold temperature shocks seasonally and measured pooled gene expression responses using RNAseq. Targeting a subset of twenty genes, we designed a high-throughput qPCR array to quantify expression in all individuals separately under each treatment with the goal of identifying thermal stress biomarkers. We observed extensive transcriptional variation in the population, suggesting abundant raw material is available for adaptation via natural selection. However, this high variation made it difficult to correlate gene expression changes with colony performance metrics such as growth, mortality, and bleaching susceptibility. Nevertheless, we identified several promising biomarkers for acute thermal stress that may improve coral restoration and climate change mitigation efforts in the future.

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Multi-year, seasonal genotypic surveys of coral-algal symbioses reveal prevalent stability or post-bleaching reversion

Cited by 357 publications

References 50 publications

Bleaching susceptibility and mortality of corals are determined by fine-scale differences in symbiont type

Bleaching susceptibility and mortality of corals are determined by fine-scale differences in symbiont type

Host–symbiont recombination versus natural selection in the response of coral–dinoflagellate symbioses to environmental disturbance

Extensive transcriptional variation poses a challenge to thermal stress biomarker development for endangered corals

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