Natural Variability in Caribbean Coral Physiology and Implications for Coral Bleaching Resilience

Coral reefs are among the most diverse and complex ecosystems in the world that provide important ecological and economical services. Increases in sea surface temperature linked to global climate change threatens these ecosystems by inducing coral bleaching. However, it is not fully known if natural intra- or inter-annual physiological variability is linked to bleaching resilience or recovery capacity of corals. Here, we monitored the coral physiology of three common Caribbean species (Porites divaricata, Porites astreoides, Orbicella faveolata) at six time points over 2 years by measuring the following traits: calcification, biomass, lipids, proteins, carbohydrates, chlorophyll a, algal endosymbiont density, stable carbon isotopes of the host and endosymbiotic algae, and the stable carbon and oxygen isotopes of the skeleton. The overall physiological profile of all three species varied over time and that of P. divaricata was consistently different from the two other coral species. Porites divaricata had higher energy reserves coupled with higher contributions of heterotrophically derived carbon to host tissues than both P. astreoides and O. faveolata. Consistently higher overall energy reserves and heterotrophic contributions to tissues appear to buffer against environmental stress, including bleaching events. Thus, natural physiological variability among coral species appears to be a stronger predictor of coral bleaching resilience than intra- or inter-annual physiological variability within a coral species.

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Annual coral bleaching and the long-term recovery capacity of coral

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.1887 ◽

2015 ◽

Vol 282 (1819) ◽

pp. 20151887 ◽

Cited By ~ 45

Author(s):

Verena Schoepf ◽

Andréa G. Grottoli ◽

Stephen J. Levas ◽

Matthew D. Aschaffenburg ◽

Justin H. Baumann ◽

...

Keyword(s):

Coral Species ◽

Elevated Temperatures ◽

Time Frame ◽

Energy Reserves ◽

Recovery Capacity ◽

Orbicella Faveolata ◽

N Isotopes ◽

C And N ◽

The Impact

Mass bleaching events are predicted to occur annually later this century. Nevertheless, it remains unknown whether corals will be able to recover between annual bleaching events. Using a combined tank and field experiment, we simulated annual bleaching by exposing three Caribbean coral species ( Porites divaricata , Porites astreoides and Orbicella faveolata ) to elevated temperatures for 2.5 weeks in 2 consecutive years. The impact of annual bleaching stress on chlorophyll a , energy reserves, calcification, and tissue C and N isotopes was assessed immediately after the second bleaching and after both short- and long-term recovery on the reef (1.5 and 11 months, respectively). While P. divaricata and O. faveolata were able to recover from repeat bleaching within 1 year, P. astreoides experienced cumulative damage that prevented full recovery within this time frame, suggesting that repeat bleaching had diminished its recovery capacity. Specifically, P. astreoides was not able to recover protein and carbohydrate concentrations. As energy reserves promote bleaching resistance, failure to recover from annual bleaching within 1 year will likely result in the future demise of heat-sensitive coral species.

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THERMAL ALTERATION OF PRECAMBRIAN MICROFOSSILS: APPLICATIONS TO THE STUDY OF STABLE CARBON ISOTOPES ON THE EARLY EARTH

10.1130/abs/2020am-359839 ◽

2020 ◽

Author(s):

Jeffrey Osterhout ◽

◽

J. William Schopf ◽

Anatoliy B. Kudryavtsev ◽

K.D. McKeegan

Keyword(s):

Carbon Isotopes ◽

Stable Carbon Isotopes ◽

Early Earth ◽

Stable Carbon ◽

Thermal Alteration

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Carbonization of Carbonates and Fractionation of Stable Carbon Isotopes in a Dynamic Slip Zone

Geochemistry International ◽

10.1134/s0016702920090062 ◽

2020 ◽

Vol 58 (9) ◽

pp. 981-993

Author(s):

Yu. A. Morozov ◽

V. S. Sevastianov ◽

A. Yu. Yurchenko ◽

O. V. Kuznetsova

Keyword(s):

Carbon Isotopes ◽

Stable Carbon Isotopes ◽

Slip Zone ◽

Stable Carbon ◽

Dynamic Slip

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Drought signals inferred from ring-width and stable carbon isotope chronologies from Thuja occidentalis trees growing at their northwestern distribution limit, central Canada

Canadian Journal of Forest Research ◽

10.1139/x2012-012 ◽

2012 ◽

Vol 42 (3) ◽

pp. 517-531 ◽

Cited By ~ 5

Author(s):

Robert Au ◽

Jacques C. Tardif

Keyword(s):

Tree Ring ◽

Tree Rings ◽

Stable Carbon Isotopes ◽

Stable Carbon Isotope ◽

Ring Width ◽

Ring Formation ◽

Moisture Regime ◽

Stable Carbon ◽

Thuja Occidentalis ◽

Central Canada

Stable carbon isotopes (δ13C) fixed in tree rings are dependent upon environmental conditions. Old northern white-cedar ( Thuja occidentalis L.) trees were sampled at their northwestern limit of distribution in central Canada. The objectives of the study were (i) to investigate the association between tree-ring δ13C values and radial growth in addition to the response of these variables to climate, (ii) to assess site differences between two sites varying in moisture regime, and (iii) to compare tree-ring δ13C of T. occidentalis with that of other boreal tree species growing at the northern limit of their distribution in central Canada. Over 2500 tree rings comprised of 15 T. occidentalis trees were analyzed for δ13C. Annually resolved δ13C (1650–2006) and ring-width (1542–2006) chronologies were developed. During the year of ring formation, ring width was associated with spring and early-summer conditions, whereas δ13C was more indicative of overall summer conditions. However, compared with δ13C values, ring width was more often associated with climate conditions in the year prior to ring formation. Conditions conducive to moisture stress were important for both parameters. Although ring width and δ13C corresponded to the drought intervals of the 1790s, 1840s, 1890s, 1930s, and 1960–1970, ring width may be more responsive to prolonged drought than δ13C. Tree-ring δ13C could, however, provide important information regarding physiological adaptations to drought.

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