scholarly journals The Third Global Coral Bleaching Event on the Marginal Coral Reefs of the Southwestern Indian Ocean and Factors That Contribute to Their Resistance and Resilience

Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 464
Author(s):  
Sean N. Porter ◽  
Kerry J. Sink ◽  
Michael H. Schleyer
Keyword(s):  
Indian Ocean ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Bleaching Event ◽  
Thermal Dynamics ◽  
Upwelled Water ◽  
Coral Communities ◽  
Temperature Records ◽  
Southwestern Indian Ocean

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.

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

PLoS ONE ◽  
2018 ◽  
Vol 13 (4) ◽  
pp. e0195814 ◽  
Author(s):  
Alison A. Monroe ◽  
Maren Ziegler ◽  
Anna Roik ◽  
Till Röthig ◽  
Royale S. Hardenstine ◽  
...  
Keyword(s):  
Red Sea ◽  
Coral Bleaching ◽  
Saudi Arabian ◽  
Bleaching Event ◽  
In Situ Observations

scholarly journals Depth-dependent mortality of reef corals following a severe bleaching event: implications for thermal refuges and population recovery

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 187 ◽  
Author(s):  
Tom C. L. Bridge ◽  
Andrew S Hoey ◽  
Stuart J Campbell ◽  
Efin Muttaqin ◽  
Edi Rudi ◽  
...  
Keyword(s):  
Shallow Water ◽  
Coral Bleaching ◽  
Cold Water ◽  
Depth Range ◽  
Bleaching Event ◽  
Sea Temperature ◽  
Local Conditions ◽  
Reef Corals ◽  
Coral Communities ◽  
High Conservation

Coral bleaching caused by rising sea temperature is a primary cause of coral reef degradation. However, bleaching patterns often show significant spatial variability, therefore identifying locations where local conditions may provide thermal refuges is a high conservation priority. Coral bleaching mortality often diminishes with increasing depth, but clear depth zonation of coral communities and putative limited overlap in species composition between deep and shallow reef habitats has led to the conclusion that deeper reef habitats will provide limited refuge from bleaching for most species. Here, we show that coral mortality following a severe bleaching event diminished sharply with depth.Bleaching-induced mortality ofAcroporawas approximately 90% at 0-2m, 60% at 3-4 m, yet at 6-8m there was negligible mortality. Importantly, at least two-thirds of the shallow-water (2-3 m)Acroporaassemblage had a depth range that straddled the transition from high to low mortality. Cold-water upwelling may have contributed to the lower mortality observed in all but the shallowest depths. Our results demonstrate that, in this instance, depth provided a refuge for individuals from a high proportion of species in thisAcropora-dominated assemblage. The persistence of deeper populations may provide a critical source of propagules to assist recovery of adjacent shallow-water reefs.

scholarly journals Depth-dependent mortality of reef corals following a severe bleaching event: implications for thermal refuges and population recovery

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 187 ◽  
Author(s):  
Tom C. L. Bridge ◽  
Andrew S Hoey ◽  
Stuart J Campbell ◽  
Efin Muttaqin ◽  
Edi Rudi ◽  
...  
Keyword(s):  
Shallow Water ◽  
Coral Bleaching ◽  
Cold Water ◽  
Depth Range ◽  
Bleaching Event ◽  
Sea Temperature ◽  
Local Conditions ◽  
Reef Corals ◽  
Coral Communities ◽  
High Conservation

Coral bleaching caused by rising sea temperature is a primary cause of coral reef degradation. However, bleaching patterns often show significant spatial variability, therefore identifying locations where local conditions may provide thermal refuges is a high conservation priority. Coral bleaching mortality often diminishes with increasing depth, but clear depth zonation of coral communities and putative limited overlap in species composition between deep and shallow reef habitats has led to the conclusion that deeper reef habitats will provide limited refuge from bleaching for most species. Here, we show that coral mortality following a severe bleaching event diminished sharply with depth.Bleaching-induced mortality ofAcroporawas approximately 90% at 0-2m, 60% at 3-4 m, yet at 6-8m there was negligible mortality. Importantly, at least two-thirds of the shallow-water (2-3 m)Acroporaassemblage had a depth range that straddled the transition from high to low mortality. Cold-water upwelling may have contributed to the lower mortality observed in all but the shallowest depths. Our results demonstrate that, in this instance, depth provided a refuge for individuals from a high proportion of species in thisAcropora-dominated assemblage. The persistence of deeper populations may provide a critical source of propagules to assist recovery of adjacent shallow-water reefs.

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

2018 ◽  
Vol 48 (1) ◽  
pp. 75-84 ◽  
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.

scholarly journals Coral reefs in the Gilbert Islands of Kiribati: Resistance, resilience, and recovery after more than a decade of multiple stressors

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255304
Author(s):  
Sara E. Cannon ◽  
Erietera Aram ◽  
Toaea Beiateuea ◽  
Aranteiti Kiareti ◽  
Max Peter ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Phase Shift ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Coral Cover ◽  
Hard Coral ◽  
Turf Algae ◽  
The World ◽  
Coral Communities

Coral reefs are increasingly affected by a combination of acute and chronic disturbances from climate change and local stressors. The coral reefs of the Republic of Kiribati’s Gilbert Islands are exposed to frequent heat stress caused by central-Pacific type El Niño events, and may provide a glimpse into the future of coral reefs in other parts of the world, where the frequency of heat stress events will likely increase due to climate change. Reefs in the Gilbert Islands experienced a series of acute disturbances over the past fifteen years, including mass coral bleaching in 2004–2005 and 2009–2010, and an outbreak of the corallivorous sea star Acanthaster cf solaris, or Crown-of-Thorns (CoTs), in 2014. The local chronic pressures including nutrient loading, sedimentation and fishing vary within the island chain, with highest pressures on the reefs in urbanized South Tarawa Atoll. In this study, we examine how recovery from acute disturbances differs across a gradient of human influence in neighboring Tarawa and Abaiang Atolls from 2012 through 2018. Benthic cover and size frequency data suggests that local coral communities have adjusted to the heat stress via shifts in the community composition to more temperature-tolerant taxa and individuals. In densely populated South Tarawa, we document a phase shift to the weedy and less bleaching-sensitive coral Porites rus, which accounted for 81% of all coral cover by 2018. By contrast, in less populated Abaiang, coral communities remained comparatively more diverse (with higher percentages of Pocillopora and the octocoral Heliopora) after the disturbances, but reefs had lower overall hard coral cover (18%) and were dominated by turf algae (41%). The CoTs outbreak caused a decline in the cover and mean size of massive Porites, the only taxa that was a ‘winner’ of the coral bleaching events in Abaiang. Although there are signs of recovery, the long-term trajectory of the benthic communities in Abaiang is not yet clear. We suggest three scenarios: they may remain in their current state (dominated by turf algae), undergo a phase shift to dominance by the macroalgae Halimeda, or recover to dominance by thermally tolerant hard coral genera. These findings provide a rare glimpse at the future of coral reefs around the world and the ways they may be affected by climate change, which may allow scientists to better predict how other reefs will respond to increasing heat stress events across gradients of local human disturbance.

Two new species of shallow-water hermit crabs (Crustacea: Decapoda: Paguridae) from Mayotte, Comoro Islands, southwestern Indian Ocean

Zootaxa ◽  
2012 ◽  
Vol 3277 (1) ◽  
pp. 56
Author(s):  
TOMOYUKI KOMAI ◽  
JOSEPH POUPIN
Keyword(s):  
New Species ◽  
Indian Ocean ◽  
Coral Reefs ◽  
Dorsal Surface ◽  
Hermit Crabs ◽  
The Third ◽  
Two New Species ◽  
The Right ◽  
Southwestern Indian Ocean ◽  
Comoro Islands

Two new species of pagurid hermit crabs are described from shallow coral reefs of Mayotte, Comoro Islands, southwest-ern Indian Ocean. Cestopagurus caeruleus sp. nov., representing the fourth of the genus, is morphological similar to C.coutieri Bouvier, 1897 and C. timidus (Roux, 1830), but the new species is immediately distinguished from the latter twospecies by the proportionally longer antennular peduncles and the different armature of the dactylus of the right cheliped.Trichopagurus asper sp. nov., representing the third species of the genus, appears closer to T. macrochela Komai & Osa-wa, 2005, but the tuberculate dorsal surface of the right palm and the possession of spines on the carpus of the left cheliped readily differentiate the new species from the latter species.

Contrasting patterns of mortality in Polynesian coral reefs following the third global coral bleaching event in 2016

Coral Reefs ◽  
2020 ◽  
Vol 39 (4) ◽  
pp. 939-952 ◽  
Author(s):  
Laetitia Hédouin ◽  
Héloïse Rouzé ◽  
Cécile Berthe ◽  
Gonzalo Perez-Rosales ◽  
Elodie Martinez ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Coral Bleaching ◽  
Bleaching Event ◽  
The Third

scholarly journals Herbivorous damselfishes expand their territories after causing white scars on Porites corals

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hiroki Hata ◽  
Shota Takano ◽  
Hiroyuki Masuhara
Keyword(s):  
Coral Reefs ◽  
Coral Bleaching ◽  
Stepping Stones ◽  
Okinawa Island ◽  
Turf Algae ◽  
Coral Communities ◽  
Algal Competition

Abstract Turf algae become the most abundant benthic group on coral reefs after mass coral bleaching. By defending feeding territories, damselfishes enhance the growth of turf algae in so-called algal farms and affect coral communities both directly and indirectly. We found several white scars (i.e., bite lesions) on massive Porites colonies around feeding territories. In this study, we examined the occurrence of white scars on corals and their function in coral–algal competition at the boundaries between algal farms of two damselfish species—the intensive farmer Stegastes nigricans, and the intermediate farmer S. lividus—and adjacent Porites corals for 3 years around Okinawa Island, Japan. White scars occurred on Porites colonies only adjacent to the territories of both damselfish species. Of the white scars on corals around S. nigricans territories, 73% of the area was covered by algae within 2 weeks, while the remaining was re-covered by Porites tissues. The coral–algal boundaries encroached further into areas of coral when the area of white scars were larger. These results suggest that both intensive and intermediate farmers bite adjacent Porites colonies causing white scars on corals, and expand their territories onto corals using algae-covered white scars as stepping stones.

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