Experimental evidence for reduced mortality of Agaricia lamarcki on a mesophotic reef

Laverick, Jack H.; Rogers, Alex D.

doi:10.1016/j.marenvres.2017.12.013

Cited by 12 publications

(12 citation statements)

References 30 publications

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“…This leads us to believe that the potential adaptation of deeper colonies may not prevent connectivity between shallow and mesophotic reefs and may permit a deep-water refuge for A. lamarcki at this location. This is supported by the lack of an observed effect of depth on the cellular oxidative stress indicator DMSO:DMSP, and by no impact of collection site on the survival of the same colonies sampled here during a transplant experiment (Laverick & Rogers, 2018). A similar situation has been noted for E. paradivisa in the Red Sea (Eyal et al ., 2015).…”

Section: Discussionsupporting

confidence: 58%

Depth alone is an inappropriate proxy for physiological change in the mesophotic coralAgaricia lamarcki

Laverick

Green

Burdett³

et al. 2019

J. Mar. Biol. Ass.

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The physiology of mesophotic Scleractinia varies with depth in response to environmental change. Previous research has documented trends in heterotrophy and photosynthesis with depth, but has not addressed between-site variation for a single species. Environmental differences between sites at a local scale and heterogeneous microhabitats, because of irradiance and food availability, are likely important factors when explaining the occurrence and physiology of Scleractinia. Here, 108 colonies of Agaricia lamarcki were sampled from two locations off the coast of Utila, Honduras, distributed evenly down the observed 50 m depth range of the species. We found that depth alone was not sufficient to fully explain physiological variation. Pulse Amplitude-Modulation fluorometry and stable isotope analyses revealed that trends in photochemical and heterotrophic activity with depth varied markedly between sites. Our isotope analyses do not support an obligate link between photosynthetic activity and heterotrophic subsidy with increasing depth. We found that A. lamarcki colonies at the bottom of the species depth range can be physiologically similar to those nearer the surface. As a potential explanation, we hypothesize sites with high topographical complexity, and therefore varied microhabitats, may provide more physiological niches distributed across a larger depth range. Varied microhabitats with depth may reduce the dominance of depth as a physiological determinant. Thus, A. lamarcki may ‘avoid’ changes in environment with depth, by instead existing in a subset of favourable niches. Our observations correlate with site-specific depth ranges, advocating for linking physiology and abiotic profiles when defining the distribution of mesophotic taxa.

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Section: Discussionsupporting

confidence: 58%

Depth alone is an inappropriate proxy for physiological change in the mesophotic coralAgaricia lamarcki

Laverick

Green

Burdett³

et al. 2019

J. Mar. Biol. Ass.

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“…MCE corals have been shown to experience drastic seasonal variations in the energetic content compared to shallow corals [73]. It is generally accepted that the ecological advantages acquired by corals in their native habitat may jeopardize their survival in cases of abrupt environmental change [74]. However, for the otherwise strictly mesophotic E. paradivisa in the Red Sea, shallow waters may be advantageous.…”

Section: Discussionmentioning

confidence: 99%

Photoacclimation and induction of light-enhanced calcification in the mesophotic coralEuphyllia paradivisa

et al. 2019

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Corals and their photosymbionts experience inherent changes in light along depth gradients, leading them to have evolved several well-investigated photoacclimation strategies. As coral calcification is influenced by light (a process described as LEC—‘light-enhanced calcification’), studies have sought to determine the link between photosynthesis and calcification, but many puzzling aspects still persist. Here, we examine the physiology of Euphyllia paradivisa , a coral species found at a wide range of depths but that is strictly mesophotic in the Red Sea; and also examines the coupling between photosynthesis and LEC by investigating the response of the coral under several controlled light regimes during a long-term experiment. E. paradivisa specimens were collected from 40 to 50 m depth and incubated under three light conditions for a period of 1 year: full-spectrum shallow-water light (approx. 3 m, e.g. shallow-light treatment); blue deep-water light (approx. 40 m, e.g. mesophotic-light treatment) or total darkness (e.g. dark treatment). Net photosynthesis remained similar in the shallow-light-treated corals compared to the mesophotic-light-treated corals, under both low and high light. However, calcification increased dramatically with increasing light intensity in the shallow-light-treated corals, suggesting a decoupling between these processes. Photoacclimation to shallow-water conditions was indicated by enhanced respiration, a higher density of zooxanthellae per polyp and lower chlorophyll a content per cell. The dark-treated corals became completely bleached but did not lower their metabolism below that of the mesophotic-light-treated corals. No Symbiodinium clade shift was found following the year-long light treatments. We conclude that E. paradivisa , and its original symbiont clade, can adapt to various light conditions by controlling its metabolic rate and growth energy investment, and consequently induce LEC.

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“…It has been suggested that MCEs can be divided into two distinct zones: an upper mesophotic one, between 30-60 m; and a lower one, below 60 m (Lesser et al, 2010;Brazeau et al, 2013;Bongaerts et al, 2015). It has also been broadly suggested that deeper reefs are less affected by direct climate-induced disturbances compared to shallow reefs (Glynn, 1996;Hughes and Tanner, 2000;Bak et al, 2005;Laverick and Rogers, 2017;Baird et al, 2018) and, therefore, the occurrence of thriving MCE communities has led to the "deep-reef refuge hypothesis" (DRRH: Bongaerts et al, 2010Bongaerts et al, , 2019. It is hypothesized that MCEs may function as a refuge for certain organisms during periods of stress in the shallow waters and, in the aftermath, act as a potential source of propagules for recovery of the disturbed shallow communities (e.g., Kahng et al, 2014;Bongaerts et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Octocoral Sexual Reproduction: Temporal Disparity Between Mesophotic and Shallow-Reef Populations

et al. 2018

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Mesophotic coral-reef ecosystems (MCEs) are light-dependent communities occurring at 30 to ∼150 m depth in the clear waters of tropical and subtropical regions. The extent to which MCEs and shallow benthic populations are connected, and whether coral sexual reproduction is maintained under the mesophotic environmental conditions, are still unclear. Despite the trend of increasing studies concerning the MCEs, the reproductive traits of MCE Indo-Pacific octocorals have remained uninvestigated to date. The current study engages with two common zooxanthellate octocorals in the northern Red Sea: the internal-brooder Ovabunda spp. and the surface-brooder Rhytisma fulvum fulvum. It addresses the hypothesis that, similar to their shallowzone conspecifics, the upper mesophotic populations also reproduce sexually. We analyze the reproductive traits of tropical, upper mesophotic octocoral populations and compare them for the first time to the traits of their conspecifics on shallow reefs. In addition, we discuss the timing of surface-brooding events in relation to lunar phase and daily seawater temperature. The populations of Ovabunda spp. in the upper MCE and shallow-water display several similar reproductive traits (e.g., maximal gonad diameter and fecundity). Consequently, this species seems to be a successful depthgeneralist. In contrast, the reproductive features of R. f. fulvum differ between the reefs in the upper MCE and in those shallow-water, with a decreased abundance of female colonies, lower fecundity, and a lower percentage of colonies exhibiting surfacebrooding in the former. It thus seems that the R. f. fulvum population encounters certain constraints in the MCE that may, in turn, lead to its reduced reproductive performance there. In addition, surface-brooding events for R. f. fulvum in the uppermesophotic zone and in shallow-water were separated by two weeks. Since a distinctive seawater temperature rise preceded each surface-brooding event, temperature regimes at different depths may present extrinsic cues that influence the timing of reproduction. The findings from this study contribute to our understanding of the life-history of mesophotic benthic inhabitants in general and of octocorals in particular. Overall, the current findings reinforce the viewpoint that the refuge potential of MCEs may be reflective of species-specific reproductive traits.

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Experimental evidence for reduced mortality of Agaricia lamarcki on a mesophotic reef

Cited by 12 publications

References 30 publications

Depth alone is an inappropriate proxy for physiological change in the mesophotic coralAgaricia lamarcki

Depth alone is an inappropriate proxy for physiological change in the mesophotic coralAgaricia lamarcki

Photoacclimation and induction of light-enhanced calcification in the mesophotic coralEuphyllia paradivisa

Octocoral Sexual Reproduction: Temporal Disparity Between Mesophotic and Shallow-Reef Populations

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