Local bleaching thresholds established by remote sensing techniques vary among reefs with deviating bleaching patterns during the 2012 event in the Arabian/Persian Gulf

Shuail, D. A.; Wiedenmann, Jörg; D’Angelo, Cecilia; Baird, Andrew H.; Pratchett, Morgan S.; Riegl, Bernhard; Burt, John A.; Petrov, P.; Amos, Carl L.

doi:10.1016/j.marpolbul.2016.03.001

Cited by 31 publications

(34 citation statements)

References 35 publications

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“…More recently, focus has shifted toward understanding the plasticity of thermal tolerance in corals, and numerous studies have identified a direct link between thermal preconditioning and bleaching susceptibility from both field observations (Castillo and Helmuth, 2005;Maynard et al, 2008;Thompson and van Woesik, 2009;Castillo et al, 2012;Shuail et al, 2016) and experimental manipulation (Brown et al, 2000(Brown et al, , 2002Dove et al, 2006;Middlebrook et al, 2008;Bellantuono et al, 2012b;Bay and Palumbi, 2015). For example, Acropora, Pocillopora, and Porites from the Great Barrier Reef showed lower rates of bleaching during the 2002 bleaching event than the 1998 event, despite more intense conditions during the 2002 event (Maynard et al, 2008).…”

Section: Thermal History and Bleaching Susceptibilitymentioning

confidence: 99%

Mechanisms of Thermal Tolerance in Reef-Building Corals across a Fine-Grained Environmental Mosaic: Lessons from Ofu, American Samoa

et al. 2018

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Environmental heterogeneity gives rise to phenotypic variation through a combination of phenotypic plasticity and fixed genetic effects. For reef-building corals, understanding the relative roles of acclimatization and adaptation in generating thermal tolerance is fundamental to predicting the response of coral populations to future climate change. The temperature mosaic in the lagoon of Ofu, American Samoa, represents an ideal natural laboratory for studying thermal tolerance in corals. Two adjacent back-reef pools approximately 500 m apart have different temperature profiles: the highly variable (HV) pool experiences temperatures that range from 24.5 to 35 • C, whereas the moderately variable (MV) pool ranges from 25 to 32 • C. Standardized heat stress tests have shown that corals native to the HV pool have consistently higher levels of bleaching resistance than those in the MV pool. In this review, we summarize research into the mechanisms underlying this variation in bleaching resistance, focusing on the important reef-building genus Acropora. Both acclimatization and adaptation occur strongly and define thermal tolerance differences between pools. Most individual corals shift physiology to become more heat resistant when moved into the warmer pool. Lab based tests show that these shifts begin in as little as a week and are equally sparked by exposure to periodic high temperatures as constant high temperatures. Transcriptome-wide data on gene expression show that a wide variety of genes are co-regulated in expression modules that change expression after experimental heat stress, after acclimatization, and even after short term environmental fluctuations. Population genetic scans show associations between a corals' thermal environment and its alleles at 100s to 1000s of nuclear genes and no single gene confers strong environmental effects within or between species. Symbionts also tend to differ between pools and species, and the thermal tolerance of a coral is a reflection of individual host genotype and specific symbiont types. We conclude the review by placing this work in the context of parallel research going on in other species, reefs, and ecosystems around the world and into the broader framework of reef coral resilience in the face of climate change.

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Section: Thermal History and Bleaching Susceptibilitymentioning

confidence: 99%

Mechanisms of Thermal Tolerance in Reef-Building Corals across a Fine-Grained Environmental Mosaic: Lessons from Ofu, American Samoa

et al. 2018

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“…The Persian/Arabian Gulf (PAG) is a thermally extreme and hypersaline body of water with temperatures regularly exceeding 34 • C during summer in its southern and hottest part (Hume et al, 2013;Shuail et al, 2016; Figure 1, Figure S1), temperatures that prove fatal to most tropical corals (Coles and Riegl, 2013;Hume et al, 2013). Yet, thriving coral communities are found along its coastline (Coles, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Such increases are causing more frequent and severe coral bleaching events (Logan et al, 2014) during which the obligate symbiotic relationship between coral and algal symbiont (genus Symbiodinium) breaks down leading to symbiont loss, and if recovery is not timely, death of the host (Hughes et al, 2003). Temperature thresholds at which these bleaching events occur are dependent on host and symbiont genotypes but typically lie 1 • C above the average maximum summer temperature for a reef (Goreau and Hayes, 1994;Shuail et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Given that the maximum mean temperature of the majority of coral reefs is ≤30 • C (Hume et al, 2013), the ability of corals from the southern PAG to withstand temperatures in excess of 35 • C without bleaching is truly exceptional (Coles and Riegl, 2013;Hume et al, 2013;Shuail et al, 2016). This exceptional thermal tolerance may be in part due to their algal associations given that hosting certain Symbiodinium types may confer an increased thermal tolerance to the coral host (LaJeunesse et al, 2010;Silverstein et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Fine-Scale Biogeographical Boundary Delineation and Sub-population Resolution in the Symbiodinium thermophilum Coral Symbiont Group From the Persian/Arabian Gulf and Gulf of Oman

et al. 2018

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The adaptation of tropical coral communities to the world's hottest sea, the Persian/Arabian Gulf (PAG), has recently been associated with ecological selection acting on a group of coral-associated algal symbionts, the Symbiodinium thermophilum group. Previous studies have shown that considerable genetic diversity exists within the group and that group members found within the PAG are significantly differentiated from those found externally, in the Gulf of Oman and wider waters. However, little is known about this genetic diversity. As an initial step towards understanding whether this diversity could represent niche adapted, selectable populations within the S. thermophilum group that may act as natural sources of stress tolerant associations to Indo-Pacific reefs, we investigate whether the diversity is structured between populations and where the location of the internal-external genetic partition lies. We use regions of the nuclear ribosomal DNA (ITS1-5.8S-ITS2) and chloroplastic psbA gene (non-coding region) from >100 S. thermophilum group-harbouring Porites spp. (P. lobata, P. lutea, and P. harrisoni) sampled across steep temperature and salinity gradients to conduct analyses of variance and create maximum parsimony networks to assess genetic structure and (dis)similarity within and between populations of S. thermophilum found within the PAG and externally in the Gulf of Oman. Our analyses resolve a sharp genetic boundary between Symbiodinium populations in the western Strait of Hormuz and identify significant genetic structure between populations with as little as 20 km between them demonstrating that differentiation between populations is likely due to factors other Hume et al.Genetically Differentiated S. thermophilum Populations than limited connectivity. Further, we hypothesize that genotypes identified outside of the PAG in the Gulf of Oman existing in near-oceanic salinities, yet thermally challenging waters, putatively represent candidates for stress-tolerant symbionts that could act as natural seed populations of stress tolerant genotypes to the wider indo-Pacific.

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“…These data, along with data from published literature (Purser, 1973;Sheppard, 1988;Fatemi and Shokri, 2001;Rezai et al, 2004Rezai et al, , 2010Purkis and Riegl, 2005;Aramco, 2007;Burt et al, 2011Burt et al, , 2013Kavousi et al, 2011;Foster et al, 2012;Riegl and Purkis, 2012;Bauman et al, 2013Bauman et al, , 2014Mohammadizadeh et al, 2013;Grizzle et al, 2016;Shuail et al, 2016), were used to produce Figure 1.…”

Section: Environmental Conditions and Coral Conditionmentioning

confidence: 99%

Demographic Mechanisms of Reef Coral Species Winnowing from Communities under Increased Environmental Stress

et al. 2017

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Winnowing of poorly-adapted species from local communities causes shifts/declines in species richness, making ecosystems increasingly ecologically depauperate. Low diversity can be associated with marginality of environments, which is increasing as climate change impacts ecosystems globally. This paper demonstrates the demographic mechanisms (size-specific mortality, growth, fertility; and metapopulation connectivity) associated with population-level changes due to thermal stress extremes for five zooxanthellate reef-coral species. Effects vary among species, leading to predictable changes in population size and, consequently, community structure. The Persian/Arabian Gulf (PAG) is an ecologically marginal reef environment with a subset of Indo-Pacific species, plus endemics. Local heating correlates with changes in coral population dynamics and community structure. Recent population dynamics of PAG corals were quantified in two phases (medium disturbed MD 1998-2010, severely disturbed SD 1996/8, 2010 with two stable states of declining coral frequency and cover. The strongest changes in life-dynamics, as expressed by transition matrices solved for MD and SD periods were in Acropora downingi and Porites harrisoni, which showed significant partial and whole-colony mortality (termed "shrinkers"). But in Dipsastrea pallida, Platygyra daedalea, Cyphastraea microphthalma the changes to life dynamics were more subtle, with only partial tissue mortality (termed "persisters"). Metapopulation models suggested recovery predominantly in species experiencing partial rather than whole-colony mortality. Increased frequency of disturbance caused progressive reduction in coral size, cover, and population fecundity. Also, the greater the frequency of disturbance, the more larval connectivity is required to maintain the metapopulation. An oceanographic model revealed important local larval retention and connectivity primarily between adjacent populations, suggesting that correlated disturbances across populations will lead to winnowing of species due to colony, tissue, and fertility losses, with resultant insufficient dispersal potential to make up for losses-especially if disturbances increase under climate change. Variable extinction Riegl et al. Coral Winnowing in PAG Reefs thresholds exist based on the susceptibility of species to disturbance ("shrinkers" vs. "persisters"), determining which species will be winnowed from the community. Besides projected changes in coral community and population structure, no species are projected to increase in cover. Increased marginality due to climate change will lead to a net loss of coral cover and novel communities in PAG.

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Local bleaching thresholds established by remote sensing techniques vary among reefs with deviating bleaching patterns during the 2012 event in the Arabian/Persian Gulf

Cited by 31 publications

References 35 publications

Mechanisms of Thermal Tolerance in Reef-Building Corals across a Fine-Grained Environmental Mosaic: Lessons from Ofu, American Samoa

Mechanisms of Thermal Tolerance in Reef-Building Corals across a Fine-Grained Environmental Mosaic: Lessons from Ofu, American Samoa

Fine-Scale Biogeographical Boundary Delineation and Sub-population Resolution in the Symbiodinium thermophilum Coral Symbiont Group From the Persian/Arabian Gulf and Gulf of Oman

Demographic Mechanisms of Reef Coral Species Winnowing from Communities under Increased Environmental Stress

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