scholarly journals Fine-scale delineation of Symbiodiniaceae genotypes on a previously bleached central Red Sea reef system demonstrates a prevalence of coral host-specific associations

Coral Reefs ◽  
2020 ◽  
Vol 39 (3) ◽  
pp. 583-601 ◽  
Author(s):  
B. C. C. Hume ◽  
A. Mejia-Restrepo ◽  
C. R. Voolstra ◽  
M. L. Berumen
Keyword(s):  
Red Sea ◽  
Coral Host ◽  
Fine Scale ◽  
Reef System

scholarly journals Fast and pervasive transcriptomic resilience and acclimation of extremely heat-tolerant coral holobionts from the northern Red Sea

2021 ◽  
Vol 118 (19) ◽  
pp. e2023298118
Author(s):  
Romain Savary ◽  
Daniel J. Barshis ◽  
Christian R. Voolstra ◽  
Anny Cárdenas ◽  
Nicolas R. Evensen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Red Sea ◽  
Thermal Tolerance ◽  
Gulf Of Aqaba ◽  
Coral Host ◽  
Rna Seq ◽  
Gene Expression Response ◽  
Stylophora Pistillata ◽  
Northern Red Sea

Corals from the northern Red Sea and Gulf of Aqaba exhibit extreme thermal tolerance. To examine the underlying gene expression dynamics, we exposed Stylophora pistillata from the Gulf of Aqaba to short-term (hours) and long-term (weeks) heat stress with peak seawater temperatures ranging from their maximum monthly mean of 27 °C (baseline) to 29.5 °C, 32 °C, and 34.5 °C. Corals were sampled at the end of the heat stress as well as after a recovery period at baseline temperature. Changes in coral host and symbiotic algal gene expression were determined via RNA-sequencing (RNA-Seq). Shifts in coral microbiome composition were detected by complementary DNA (cDNA)-based 16S ribosomal RNA (rRNA) gene sequencing. In all experiments up to 32 °C, RNA-Seq revealed fast and pervasive changes in gene expression, primarily in the coral host, followed by a return to baseline gene expression for the majority of coral (>94%) and algal (>71%) genes during recovery. At 34.5 °C, large differences in gene expression were observed with minimal recovery, high coral mortality, and a microbiome dominated by opportunistic bacteria (including Vibrio species), indicating that a lethal temperature threshold had been crossed. Our results show that the S. pistillata holobiont can mount a rapid and pervasive gene expression response contingent on the amplitude and duration of the thermal stress. We propose that the transcriptomic resilience and transcriptomic acclimation observed are key to the extraordinary thermal tolerance of this holobiont and, by inference, of other northern Red Sea coral holobionts, up to seawater temperatures of at least 32 °C, that is, 5 °C above their current maximum monthly mean.

scholarly journals Spatial and Species Variations in Bacterial Communities Associated with Corals from the Red Sea as Revealed by Pyrosequencing

2012 ◽  
Vol 78 (20) ◽  
pp. 7173-7184 ◽  
Author(s):  
On On Lee ◽  
Jiangke Yang ◽  
Salim Bougouffa ◽  
Yong Wang ◽  
Zenon Batang ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Red Sea ◽  
Host Species ◽  
Bacterial Communities ◽  
Coral Species ◽  
Rrna Gene ◽  
Coral Host ◽  
Dominant Group ◽  
Content Type ◽  
Bacterial Phyla

ABSTRACTMicrobial associations with corals are common and are most likely symbiotic, although their diversity and relationships with environmental factors and host species remain unclear. In this study, we adopted a 16S rRNA gene tag-pyrosequencing technique to investigate the bacterial communities associated with three stony Scleractinea and two soft Octocorallia corals from three locations in the Red Sea. Our results revealed highly diverse bacterial communities in the Red Sea corals, with more than 600 ribotypes detected and up to 1,000 species estimated from a single coral species. Altogether, 21 bacterial phyla were recovered from the corals, of whichGammaproteobacteriawas the most dominant group, andChloroflexi,Chlamydiae, and the candidate phylumWS3were reported in corals for the first time. The associated bacterial communities varied greatly with location, where environmental conditions differed significantly. Corals from disturbed areas appeared to share more similar bacterial communities, but larger variations in community structures were observed between different coral species from pristine waters. Ordination methods identified salinity and depth as the most influential parameters affecting the abundance ofVibrio,Pseudoalteromonas,Serratia,Stenotrophomonas,Pseudomonas, andAchromobacterin the corals. On the other hand, bacteria such asChloracidobacteriumandEndozoicomonaswere more sensitive to the coral species, suggesting that the host species type may be influential in the associated bacterial community, as well. The combined influences of the coral host and environmental factors on the associated microbial communities are discussed. This study represents the first comparative study using tag-pyrosequencing technology to investigate the bacterial communities in Red Sea corals.

scholarly journals Nutrient-supplying ocean currents modulate coral bleaching susceptibility

2020 ◽  
Vol 6 (34) ◽  
pp. eabc5493 ◽  
Author(s):  
Thomas M. DeCarlo ◽  
Laura Gajdzik ◽  
Joanne Ellis ◽  
Darren J. Coker ◽  
May B. Roberts ◽  
...  
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Coral Reef ◽  
Red Sea ◽  
Coral Bleaching ◽  
Ocean Currents ◽  
Limited Resources ◽  
Reef System ◽  
Coral Reef System ◽  
Mass Bleaching

With predictions that mass coral bleaching will occur annually within this century, conservation efforts must focus their limited resources based on an accurate understanding of the drivers of bleaching. Here, we provide spatial and temporal evidence that excess nutrients exacerbate the detrimental effects of heat stress to spark mass coral bleaching in the Red Sea. Exploiting this region’s unique oceanographic regime, where nutrients and heat stress vary independently, we demonstrate that the world’s third largest coral reef system historically suffered from severe mass bleaching only when exposed to both unusually high temperature and nutrients. Incorporating nutrient-supplying ocean currents and their variability into coral bleaching forecasts will be critical for effectively guiding efforts to safeguard the reefs most likely to persist in the Anthropocene.

scholarly journals Coral Symbiodinium community composition across the Belize Mesoamerican Barrier Reef System is influenced by host species and thermal variability

2017 ◽  
Author(s):  
JH Baumann ◽  
SW Davies ◽  
HE Aichelman ◽  
KD Castillo
Keyword(s):  
Community Composition ◽  
Host Species ◽  
Thermal Tolerance ◽  
Environmental Variables ◽  
Coral Host ◽  
Barrier Reef ◽  
Reef System ◽  
Mesoamerican Barrier Reef System ◽  
Thermal Regimes ◽  
Mesoamerican Barrier Reef

AbstractReef-building corals maintain a symbiotic relationship with dinoflagellate algae of the genus Symbiodinium and this symbiosis is vital for the survival of the coral holobiont. Symbiodinium community composition within the coral host has been shown to influence a coral’s ability to resist and recover from stress. A multitude of stressors including ocean warming, ocean acidification, and eutrophication have been linked to global scale decline in coral health and cover in recent decades. Three distinct thermal regimes (highTP, modTP, and lowTP) following an inshore-offshore gradient of declining average temperatures and thermal variation were identified on the Belize Mesoamerican Barrier Reef System (MBRS). Quantitative metabarcoding of the ITS-2 locus was employed to investigate differences and similarities in Symbiodinium genetic diversity of the Caribbean corals Siderastrea siderea, S. radians, and Pseudodiploria strigosa between the three thermal regimes. A total of ten Symbiodinium lineages were identified across the three coral host species. Siderastrea siderea associated with distinct Symbiodinium communities, however Symbiodinium communities of its congener, S. radians, and P. strigosa, were more similar to one another. Thermal regime played a role in defining Symbiodinium communities in S. siderea but not S. radians or P. strigosa. Against expectations, Symbiodinium trenchii, a symbiont known to confer thermal tolerance, was dominant only in S. siderea at one sampled offshore site and was rare inshore, suggesting that coral thermal tolerance in more thermally variable inshore habitats is achieved through alternative mechanisms. Overall, thermal parameters alone were likely not the only primary drivers of Symbiodinium community composition, suggesting that environmental variables unrelated to temperature (i.e., light availability, or nutrients) may play key roles in structuring coral-algal communities in Belize and that the relative importance of these environmental variables may vary by coral host species.

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

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.

scholarly journals Fine-scale metabolic discontinuity in a stratified prokaryote microbiome of a Red Sea deep halocline

2021 ◽  
Author(s):  
Grégoire Michoud ◽  
David Kamanda Ngugi ◽  
Alan Barozzi ◽  
Giuseppe Merlino ◽  
Maria Ll. Calleja ◽  
...  
Keyword(s):  
Nitrogen Cycling ◽  
Red Sea ◽  
Deep Sea ◽  
Metabolic Networks ◽  
Spatial Organization ◽  
Ammonia Oxidation ◽  
Salinity Gradient ◽  
Fine Scale ◽  
High Concentration ◽  
Anoxic Basins

AbstractDeep-sea hypersaline anoxic basins are polyextreme environments in the ocean’s interior characterized by the high density of brines that prevents mixing with the overlaying seawater, generating sharp chemoclines and redoxclines up to tens of meters thick that host a high concentration of microbial communities. Yet, a fundamental understanding of how such pycnoclines shape microbial life and the associated biogeochemical processes at a fine scale, remains elusive. Here, we applied high-precision sampling of the brine–seawater transition interface in the Suakin Deep, located at 2770 m in the central Red Sea, to reveal previously undocumented fine-scale community structuring and succession of metabolic groups along a salinity gradient only 1 m thick. Metagenomic profiling at a 10-cm-scale resolution highlighted spatial organization of key metabolic pathways and corresponding microbial functional units, emphasizing the prominent role and significance of salinity and oxygen in shaping their ecology. Nitrogen cycling processes are especially affected by the redoxcline with ammonia oxidation processes being taxa and layers specific, highlighting also the presence of novel microorganisms, such as novel Thaumarchaeota and anammox, adapted to the changing conditions of the chemocline. The findings render the transition zone as a critical niche for nitrogen cycling, with complementary metabolic networks, in turn underscoring the biogeochemical complexity of deep-sea brines.

High Resolution Stereography of Complementary Freeze-Fracture Replicas Reveals the Presence of Depressions Opposite Membrane Associated Particles of Split Membranes

1971 ◽  
Vol 29 ◽  
pp. 442-443
Author(s):  
Russell L. Steere
Keyword(s):  
High Resolution ◽  
Cardiac Muscle ◽  
Electron Micrographs ◽  
Chromic Acid ◽  
Freeze Fracture ◽  
Distilled Water ◽  
Fine Scale ◽  
Acid Cleaning ◽  
Cleaning Solution

Complementary replicas have revealed the fact that the two common faces observed in electron micrographs of freeze-fracture and freeze-etch specimens are complementary to each other and are thus the new faces of a split membrane rather than the original inner and outer surfaces (1, 2 and personal observations). The big question raised by published electron micrographs is why do we not see depressions in the complementary face opposite membrane-associated particles? Reports have appeared indicating that some depressions do appear but complementarity on such a fine scale has yet to be shown.Dog cardiac muscle was perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (material furnished by Dr. Joaquim Sommer, Duke Univ., and VA Hospital, Durham, N.C.). Small strips were freeze-fractured in a Denton Vacuum DFE-2 Freeze-Etch Unit with complementary replica tooling. Replicas were cleaned in chromic acid cleaning solution, then washed in 4 changes of distilled water and mounted on opposite sides of the center wire of a Formvar-coated grid.

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