Symbiotic associations of the deepest recorded photosynthetic scleractinian coral (172 m depth)

Rouzé, Héloïse; Galand, Pierre E.; Medina, Mónica; Bongaerts, Pim; Pichon, Michel; Pérez‐Rosales, Gonzalo; Torda, Gergely; Moya, Aurélie; Raina, Jean-Baptiste; Hédouin, Laëtitia

doi:10.1038/s41396-020-00857-y

Cited by 35 publications

(30 citation statements)

References 30 publications

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“…Second, because satellite measurements are relevant only for shallow waters, we also deployed in situ temperature (HOBO Water Temperature Pro v. 2 Data) and light (DEFI2-L JFE Advantech) loggers that measured light for photosynthetically active radiation (PAR) at the different sampling depths. A detailed explanation of how these data were collected, normalized according to 6 m depth because it was the departing reference for loggers and bleaching assessments and processed using the Beer-Lambert equation [27,28] are available in electronic supplementary material, figures S2 and S3.…”

Section: Environmental Parametersmentioning

confidence: 99%

Mesophotic coral communities escape thermal coral bleaching in French Polynesia

et al. 2021

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Climate change and consequent coral bleaching are causing the disappearance of reef-building corals worldwide. While bleaching episodes significantly impact shallow waters, little is known about their impact on mesophotic coral communities. We studied the prevalence of coral bleaching two to three months after a heat stress event, along an extreme depth range from 6 to 90 m in French Polynesia. Bayesian modelling showed a decreasing probability of bleaching of all coral genera over depth, with little to no bleaching observed at lower mesophotic depths (greater than or equal to 60 m). We found that depth-generalist corals benefit more from increasing depth than depth-specialists (corals with a narrow depth range). Our data suggest that the reduced prevalence of bleaching with depth, especially from shallow to upper mesophotic depths (40 m), had a stronger relation with the light-irradiance attenuation than temperature. While acknowledging the geographical and temporal variability of the role of mesophotic reefs as spatial refuges during thermal stress, we ought to understand why coral bleaching reduces with depth. Future studies should consider repeated monitoring and detailed ecophysiological and environmental data. Our study demonstrated how increasing depth may offer a level of protection and that lower mesophotic communities could escape the impacts of a thermal bleaching event.

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Section: Environmental Parametersmentioning

confidence: 99%

Mesophotic coral communities escape thermal coral bleaching in French Polynesia

et al. 2021

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“…While both local populations and scientists have known shallow coral reef communities for centuries, coral ecosystems below 30 m depth are still largely unknown. These ecosystems, referred to as mesophotic coral ecosystems (MCEs), are found between 30-40 m depth and down to about 170 m depth depending on the locations (Hinderstein et al 2010;Rouzé et al 2021). In the late 1960's in Okinawa, Dr. Yamazato, who was the director of Sesoko Station for a long time, reported for the first time on coral communities down to 100 m depth in various places in the Ryukyu Islands.…”

Section: Introductionmentioning

confidence: 99%

Overview of the mesophotic coral ecosystems around Sesoko Island, Okinawa, Japan

Sinniger

Albelda

Prasetia

et al. 2022

Galaxea, Journal of Coral Reef Studies

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“…The host sea anemones may also have acclimated to depth in other ways as they were darker, larger and flatter, all changes likely linked to adaptations to cope with the lower access to light. In a similar manner to corals growing at depth, the flattened shape of anemones may be linked to the lower availability of light, a lower photosynthetic rate and lower growth [49] and the clade of symbiodinium may be the same at depth, as shown up to 172 m [64]. The change in anemone colour may be an adaptation of pigments to increase photosynthesis under low light conditions.…”

Section: Discussionmentioning

confidence: 89%

Deep Heat: A Comparison of Water Temperature, Anemone Bleaching, Anemonefish Density and Reproduction between Shallow and Mesophotic Reefs

Haguenauer

Zuberer

Siu

et al. 2021

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French Polynesia is experiencing increasing coral bleaching events in shallow waters triggered by thermal anomalies and marine heatwaves linked to climate change, a trend that is replicated worldwide. As sea surface thermal anomalies are assumed to lessen with depth, mesophotic deep reefs have been hypothesized to act as refuges from anthropogenic and natural disturbances, the ‘deep reef refugia hypothesis’ (DRRH). However, evidence supporting the DRRH is either inconclusive or conflicting. We address this by investigating four assumptions of the DRRH focusing on the symbiotic association between anemones and anemonefish. First, we compare long-term temperature conditions between shallow (8 m) and mesophotic sites (50 m) on the island of Moorea from 2011–2020. Second, we compare the densities of the orange-fin anemonefish, Amphiprion chrysopterus between shallow and mesophotic (down to 60 m) reefs across three archipelagos in French Polynesia. Finally, we compare the percentage of anemone bleaching, as well as anemonefish reproduction, between shallow and mesophotic reefs. We found that the water column was well mixed in the cooler austral winter months with only a 0.19 °C difference in temperature between depths, but in the warmer summer months mixing was reduced resulting in a 0.71–1.03 °C temperature difference. However, during thermal anomalies, despite a time lag in warm surface waters reaching mesophotic reefs, there was ultimately a 1.0 °C increase in water temperature at both 8 and 50 m, pushing temperatures over bleaching thresholds at both depths. As such, anemone bleaching was observed in mesophotic reefs during these thermal anomalies, but was buffered compared to the percentage of bleaching in shallower waters, which was nearly five times greater. Our large-scale sampling across French Polynesia found orange-fin anemonefish, A. chrysopterus, in mesophotic zones in two high islands and one atoll across two archipelagos, extending its bathymetric limit to 60 m; however, orange-fin anemonefish densities were either similar to, or 25–92 times lower than in shallower zones. Three spawning events were observed at 50 m, which occurred at a similar frequency to spawning on shallower reefs at the same date. Our findings of thermal anomalies and bleaching in mesophotic reefs, coupled with mainly lower densities of anemonefish in mesophotic populations, suggest that mesophotic reefs show only a limited ability to provide refugia from anthropogenic and natural disturbances.

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Symbiotic associations of the deepest recorded photosynthetic scleractinian coral (172 m depth)

Cited by 35 publications

References 30 publications

Mesophotic coral communities escape thermal coral bleaching in French Polynesia

Mesophotic coral communities escape thermal coral bleaching in French Polynesia

Overview of the mesophotic coral ecosystems around Sesoko Island, Okinawa, Japan

Deep Heat: A Comparison of Water Temperature, Anemone Bleaching, Anemonefish Density and Reproduction between Shallow and Mesophotic Reefs

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