Millennial‐scale change on a Caribbean reef system that experiences hypoxia

Figuerola, Blanca; Grossman, Ethan L.; Lucey, Noelle; Leonard, Nicole D.; O’Dea, Aaron

doi:10.1111/ecog.05606

Cited by 8 publications

(5 citation statements)

References 67 publications

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“…Severe decreases in nocturnal DO concentrations have been documented in Australia due to warming, which decreases oxygen solubility and increases the rate of biological oxygen consumption. In certain regions of the Caribbean, it is also known that oxygen levels may go below 2 mg/L as a result of anthropogenic eutrophication and nutrient input, and these hypoxic episodes usually last several days [ 10 , 15 , 17 , 36 , 43 , 66 ]. Acropora coral species are known to exhibit high susceptibility to climate change, including ocean warming and deoxygenation [ 10 , 15 , 27 , 34 , 67 , 68 ].…”

Section: Discussionmentioning

confidence: 99%

“…This happens as the coral polyp expels the zooxanthellae, turning the colony into white or pale colours [ 35 ]. Marine hypoxia is known to impact corals’ health and can cause bleaching [ 10 , 36 ]. Global efforts to observe the impacts of hypoxia on coral reefs have only recently increased [ 3 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

“…For instance, coral reefs in the Caribbean exhibited episodic anthropogenic hypoxia with lowest O 2 content of around 0.5 mg O 2 /L, causing coral bleaching and mortality. Additionally, the northern Gulf of Mexico and East China Sea showed patterns of increasing hypoxic areas due to high nutrient loading [ 10 , 24 , 36 , 45 , 46 , 47 ]. Occurrence of nocturnal hypoxia is a more recurrent phenomena and higher threat as generally anticipated.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Hypoxia on Coral Photobiology and Oxidative Stress

Deleja

Paula

Repolho

et al. 2022

Biology

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Global ocean oxygen (O2) content is decreasing as climate change drives declines in oxygen solubility, strengthened stratification of seawater masses, increased biological oxygen consumption and coastal eutrophication. Studies on the biological effects of nocturnal decreased oxygen concentrations (hypoxia) on coral reefs are very scarce. Coral reefs are fundamental for supporting one quarter of all marine species and essential for around 275 million people worldwide. This study investigates acute physiological and photobiological responses of a scleractinian coral (Acropora spp.) to overnight hypoxic conditions (<2 mg/L of O2). Bleaching was not detected, and visual and physical aspects of corals remained unchanged under hypoxic conditions. Most photobiological-related parameters also did not show significant changes between treatments. In addition to this, no significant differences between treatments were observed in the pigment composition. However, hypoxic conditions induced a significant decrease in coral de-epoxidation state of the xanthophyll cycle pigments and increase in DNA damage. Although the present findings suggest that Acropora spp. is resilient to some extent to short-term daily oxygen oscillations, long-term exposure to hypoxia, as predicted to occur with climate change, may still have deleterious effects on corals.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Hypoxia on Coral Photobiology and Oxidative Stress

Deleja

Paula

Repolho

et al. 2022

Biology

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“…In addition to coral colonies in the experimental plots, three colonies of S. siderea were sampled from Tierra Oscura where hypoxia has been previously documented and three colonies each of A. lamarcki and S. siderea were sampled from Finca where hypoxia has not been documented ( Fig. 1 ) ( 40 , 44 , 45 ). Slurries of coral mucus/tissue were collected by agitation and suction of the coral surface with individual sterile needleless syringes.…”

Section: Methodsmentioning

confidence: 99%

Shifts in the coral microbiome in response to in situ experimental deoxygenation

Howard,

Schul,

Rodriguez Bravo

et al. 2023

Appl Environ Microbiol

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Global climate change impacts marine ecosystems through rising surface temperatures, ocean acidification, and deoxygenation. While the response of the coral holobiont to the first two effects has been relatively well studied, less is known about the response of the coral microbiome to deoxygenation. In this study, we investigated the response of the microbiome to hypoxia in two coral species that differ in their tolerance to hypoxia. We conducted in situ oxygen manipulations on a coral reef in Bahía Almirante on the Caribbean coast of Panama, which has previously experienced documented episodes of hypoxia. Naïve coral colonies (previously unexposed to hypoxia) of Siderastrea siderea and Agaricia lamarcki were transplanted to a reef and either enclosed in chambers that created hypoxic conditions or left at ambient oxygen levels. We collected samples of surface mucus and tissue after 48 hours of exposure and characterized the microbiome by sequencing 16S rRNA genes. We found that the microbiomes of the two coral species were distinct from one another and remained so after exhibiting similar shifts in microbiome composition in response to hypoxia. There was an increase in both abundance and number of taxa of anaerobic microbes after exposure to hypoxia. Some of these taxa may play beneficial roles in the coral holobiont by detoxifying the surrounding environment during hypoxic stress or may represent opportunists exploiting host stress. This work describes the first characterization of the coral microbiome under hypoxia and is an initial step toward identifying potential beneficial bacteria for corals facing this environmental stressor. IMPORTANCE Marine hypoxia is a threat for corals but has remained understudied in tropical regions where coral reefs are abundant. Though microbial symbioses can alleviate the effects of ecological stress, we do not yet understand the taxonomic or functional response of the coral microbiome to hypoxia. In this study, we experimentally lowered oxygen levels around Siderastrea siderea and Agaricia lamarcki colonies in situ to observe changes in the coral microbiome in response to deoxygenation. Our results show that hypoxia triggers a stochastic change of the microbiome overall, with some bacterial families changing deterministically after just 48 hours of exposure. These families represent an increase in anaerobic and opportunistic taxa in the microbiomes of both coral species. Thus, marine deoxygenation destabilizes the coral microbiome and increases bacterial opportunism. This work provides novel and fundamental knowledge of the microbial response in coral during hypoxia and may provide insight into holobiont function during stress.

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“…The experimental oxygen manipulation was conducted for 48 hours, at which time the coral surface microbiome was sampled. In addition to coral colonies in the experimental plots, three colonies of S. siderea were sampled from Tierra Oscura where hypoxia has been previously documented and three colonies each of A. lamarcki and S. siderea were sampled from Finca where hypoxia has not been documented (Figure S1) (38,42,43). Coral mucus/tissue samples were collected by agitation and suction of the coral surface with individual sterile needleless syringes.…”

Section: In Situ Oxygen Manipulationmentioning

confidence: 99%

Shifts in the coral microbiome in response toin situexperimental deoxygenation

Howard

Schul

Bravo

et al. 2023

Preprint

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Global climate change impacts ocean communities through rising surface temperatures, ocean acidification, and deoxygenation. While the response of the coral holobiont to the first two effects has been relatively well studied, little is known about the response of the coral microbiome to deoxygenation. In this study, we investigated the response of the microbiome to hypoxia in two coral species that differ in their relative tolerance to hypoxia. We conductedin situoxygen manipulations on a coral reef in Bahía Almirante, Panama, which has previously experienced episodes of low dissolved oxygen concentrations. Naïve coral colonies (previously unexposed to hypoxia) of massive starlet coral (Siderastrea siderea) and Lamarck’s sheet coral (Agaricia lamarcki) were transplanted to a reef and either enclosed in chambers that created hypoxic conditions or left at ambient oxygen levels. We collected samples of surface mucus and tissue after 48 hours of exposure and characterized the microbiome by sequencing 16S rRNA genes. We found that the microbiomes of the two coral species were distinct from one another and remained so after exhibiting similar shifts in microbiome composition in response to hypoxia. There was an increase in both abundance and number of taxa of anaerobic microbes after exposure to hypoxia. Some of these taxa may play beneficial roles in the coral holobiont by detoxifying the surrounding environment during hypoxic stress. This work describes the first characterization of the coral microbiome under hypoxia and is an initial step toward identifying potential beneficial bacteria for corals facing this environmental stressor.

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Millennial‐scale change on a Caribbean reef system that experiences hypoxia

Cited by 8 publications

References 67 publications

Effects of Hypoxia on Coral Photobiology and Oxidative Stress

Effects of Hypoxia on Coral Photobiology and Oxidative Stress

Shifts in the coral microbiome in response to in situ experimental deoxygenation

Shifts in the coral microbiome in response toin situexperimental deoxygenation

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