In situ observations of coral bleaching in the central Saudi Arabian Red Sea during the 2015/2016 global coral bleaching event

Coral reefs reach their southernmost limits in the southwestern Indian Ocean in Maputaland, South Africa. Here, we investigate the recent global coral bleaching event of 2016, the thermal dynamics of these marginal high-latitude reefs and the potential environmental factors regulating the responses of coral communities. Pre-, peak- and post-bleaching surveys of over 9850 coral colonies from 29 genera were undertaken over 3 years across 14 sites spanning 120 km of coastline using point-intercept and visual bleaching index survey methodologies. Bleaching data were related to several environmental variables including temperature, degree heating weeks (DHW), depth, latitude, and upwelling intensity. These reefs have experienced a history of relatively low thermal stress based on DHW. Long-term in situ temperature records nevertheless showed no obvious trend of increase. In situ temperatures also displayed poor relationships, with temperatures predicted by the Representative Concentration Pathway models. Mild coral bleaching with no significant mortality was recorded across sites with taxon-specific bleaching responses evident. Latitude and cumulative daily DHW were significantly related to the bleaching index whereas depth and interactions of depth with latitude and DHW were not. While upwelling of cooler water may offer some refuge to coral communities, especially in the Central and Southern Reef Complexes where it is more pronounced, this may only be transient as the upwelled water may also experience some degree of warming in future, thereby limiting such protection from global warming.

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Peer Review #2 of "The past century of coral bleaching in the Saudi Arabian central Red Sea (v0.1)"

10.7287/peerj.10200v0.1/reviews/2 ◽

2020 ◽

Author(s):

M Fine

Keyword(s):

Peer Review ◽

Red Sea ◽

Coral Bleaching ◽

Saudi Arabian ◽

Past Century ◽

The Past

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The past century of coral bleaching in the Saudi Arabian central Red Sea

PeerJ ◽

10.7717/peerj.10200 ◽

2020 ◽

Vol 8 ◽

pp. e10200

Author(s):

Thomas M. DeCarlo

Keyword(s):

Coral Reef ◽

Red Sea ◽

Coral Bleaching ◽

Saudi Arabian ◽

Outer Shelf ◽

Past Century ◽

Spatial And Temporal Patterns ◽

Late 20Th Century ◽

The Past ◽

Coral Reef Ecosystems

Accurate knowledge of the spatial and temporal patterns of coral bleaching is essential both for understanding how coral reef ecosystems are changing today and forecasting their future states. Yet, in many regions of the world, the history of bleaching is poorly known, especially prior to the late 20th century. Here, I use the information preserved within skeleton cores of long-lived Porites corals to reconstruct the past century of bleaching events in the Saudi Arabian central Red Sea. In these cores, skeletal “stress bands”—indicative of past bleaching—captured known bleaching events that occurred in 1998 and 2010, but also revealed evidence of previously unknown bleaching events in 1931, 1978, and 1982. However, these earlier events affected a significantly lesser proportion of corals than 1998 and 2010. Therefore, coral bleaching may have occurred in the central Red Sea earlier than previously recognized, but the frequency and severity of bleaching events since 1998 on nearshore reefs is unprecedented over the past century. Conversely, corals living on mid- to outer-shelf reefs have not been equally susceptible to bleaching as their nearshore counterparts, which was evident in that stress bands were five times more prevalent nearshore. Whether this pattern of susceptible nearshore reefs and resistant outer-shelf reefs continues in the future remains a key question in forecasting coral reef futures in this region.

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In Situ Observations of Foraminiferal Bleaching in the Maldives, Indian Ocean

The Journal of Foraminiferal Research ◽

10.2113/gsjfr.48.1.75 ◽

2018 ◽

Vol 48 (1) ◽

pp. 75-84 ◽

Cited By ~ 8

Author(s):

Silvia Spezzaferri ◽

Akram El Kateb ◽

Chiara Pisapia ◽

Pamela Hallock

Keyword(s):

Oxidative Stress ◽

Coral Reefs ◽

Coral Bleaching ◽

Solar Irradiance ◽

Reef Management ◽

Recent Onset ◽

The North ◽

Management Plans ◽

In Situ Observations

Abstract Coral reefs are threatened worldwide by a variety of natural and human-induced stressors; anomalous temperatures are presently among the most serious threats by causing extensive coral bleaching. Amphistegina spp. exhibit similar bleaching as corals in the presence of photo-oxidative stress induced by either light or temperature, especially during times of maximum solar irradiance. At 11 islands (34 sampling sites) in the North Ari Atoll in the Maldives, bleaching in Amphistegina was observed a few weeks before the onset of an extensive El Niño-related coral bleaching that was more severe than expected for this region. Assessment using the Amphistegina Bleaching Index (ABI) showed that the proportions of bleached specimens of Amphistegina in April–May 2015 can be explained by photo-inhibitory stress associated with temperatures exceeding 30°C during peak seasonal solar irradiance and water transparency. Importantly, the ABI indicates that environmental conditions are suitable for Amphistegina and other calcifying symbioses at most of the investigated sites, and that either chronic or relatively recent onset of photo-oxidative stress was present at the time of sampling. The observed bleaching in Amphistegina further demonstrates the potential of these unicellular protists to identify stressors in coral reefs; such applications should be considered in future reef-management plans.

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The Interannual Variability of Sea Surface Temperature in the Red Sea From 35 Years of Satellite and In Situ Observations

Journal of Geophysical Research Oceans ◽

10.1029/2017jc013320 ◽

2018 ◽

Vol 123 (8) ◽

pp. 5824-5841 ◽

Cited By ~ 6

Author(s):

Kristopher B. Karnauskas ◽

Burton H. Jones

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Interannual Variability ◽

Red Sea ◽

Sea Surface ◽

In Situ Observations

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Symbiodiniaceae conduct under natural bleaching stress during advanced gametogenesis stages of the mesophotic coral Alveopora allingi

10.1101/2021.03.25.437087 ◽

2021 ◽

Author(s):

Gal Eyal ◽

Lee Eyal-Shaham ◽

Yossi Loya

Keyword(s):

Structural Material ◽

Red Sea ◽

Coral Bleaching ◽

Coral Host ◽

Bleaching Event ◽

Peripheral Areas

AbstractThe mesophotic coral Alveopora allingi from the northern Gulf of Eilat/Aqaba, Red Sea, is affected by year-round partial coral-bleaching events. During these events, the migration of Symbiodiniaceae takes place from the coral-host mesoglea to the developed oocytes in bleached parts of colonies of A. allingi but not in the non-bleached parts. Additionally, these oocytes are abnormal, missing part of the structural material of the peripheral areas and are also significantly larger in the bleached areas of the colonies. Hence, we suggest a parasitic behavior of the symbionts or a commensalism relationship which enhance symbionts’ needs during bleaching periods and may boost the gametogenesis development in these corals. We propose that evolutionarily, this behavior may greatly contribute to the symbiont community survival throughout the bleaching period, and it can also be beneficial for the host’s persistence and adaptation to bleaching through the acquisition of a specific symbiont community following the bleaching event.

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The abundance of herbivorous fish on an inshore Red Sea reef following a mass coral bleaching event

Environmental Biology of Fishes ◽

10.1007/s10641-012-0103-5 ◽

2013 ◽

Vol 96 (9) ◽

pp. 1065-1072 ◽

Cited By ~ 19

Author(s):

Maha T. Khalil ◽

Jesse E. M. Cochran ◽

Michael L. Berumen

Keyword(s):

Red Sea ◽

Coral Bleaching ◽

Herbivorous Fish ◽

Bleaching Event

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Temporal evolution of temperatures in the Red Sea and the Gulf of Aden based on in situ observations (1958–2017)

Ocean Science ◽

10.5194/os-16-149-2020 ◽

2020 ◽

Vol 16 (1) ◽

pp. 149-166

Author(s):

Miguel Agulles ◽

Gabriel Jordà ◽

Burt Jones ◽

Susana Agustí ◽

Carlos M. Duarte

Keyword(s):

Red Sea ◽

Temporal Evolution ◽

Optimal Interpolation ◽

Strong Impact ◽

Gulf Of Aden ◽

In Situ Observations ◽

Spatio Temporal ◽

Good Agreement

Abstract. The Red Sea holds one of the most diverse marine ecosystems in the world, although fragile and vulnerable to ocean warming. Several studies have analysed the spatio-temporal evolution of temperature in the Red Sea using satellite data, thus focusing only on the surface layer and covering the last ∼30 years. To better understand the long-term variability and trends of temperature in the whole water column, we produce a 3-D gridded temperature product (TEMPERSEA) for the period 1958–2017, based on a large number of in situ observations, covering the Red Sea and the Gulf of Aden. After a specific quality control, a mapping algorithm based on optimal interpolation have been applied to homogenize the data. Also, an estimate of the uncertainties of the product has been generated. The calibration of the algorithm and the uncertainty computation has been done through sensitivity experiments based on synthetic data from a realistic numerical simulation. TEMPERSEA has been compared to satellite observations of sea surface temperature for the period 1981–2017, showing good agreement especially in those periods when a reasonable number of observations were available. Also, very good agreement has been found between air temperatures and reconstructed sea temperatures in the upper 100 m for the whole period 1958–2017, enhancing confidence in the quality of the product. The product has been used to characterize the spatio-temporal variability of the temperature field in the Red Sea and the Gulf of Aden at different timescales (seasonal, interannual and multidecadal). Clear differences have been found between the two regions suggesting that the Red Sea variability is mainly driven by air–sea interactions, while in the Gulf of Aden the lateral advection of water plays a relevant role. Regarding long-term evolution, our results show only positive trends above 40 m depth, with maximum trends of 0.045 + 0.016 ∘C decade−1 at 15 m, and the largest negative trends at 125 m (-0.072+0.011 ∘C decade−1). Multidecadal variations have a strong impact on the trend computation and restricting them to the last 30–40 years of data can bias high the trend estimates.

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