A rapid in situ fluorescence census for coral reef monitoring

Ramesh, Ch.; Sadhukhan, Koushik; Shunmugaraj, T.; Murthy, M.V. Ramana

doi:10.1016/j.rsma.2019.100575

Cited by 8 publications

(8 citation statements)

References 21 publications

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“…The current findings reinforce the results of previous studies on the regulation and role of FPs under thermal stress (DeSalvo et al 2008;Smith-Keune and Dove 2008;Roth and Deheyn 2013). Since fluorescence is a visual phenomenon, it has been proposed as a useful tool for detecting very early stages of coral settlement (Zweifler et al 2017), onset of diseases (Ramesh et al 2019), and as a general tool for assessing coral health . Together with the significant decrease in fluorescence during the onset of bleaching in corals under the HT treatment, we further support the suggestion that fluorescence monitoring could be used as a noninvasive and inexpensive technique for the detection of bleaching, although this technique might be relevant only for fluorescent species or morphs.…”

Section: Discussionsupporting

confidence: 89%

Experimental evidence of temperature-induced bleaching in two fluorescence morphs of a Red Sea mesophotic coral

et al. 2020

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Coral bleaching, as one of the major threats to the well-being of coral reefs worldwide, has been extensively studied. However, corals from mesophotic coral ecosystems (MCEs), found at 30 to 150 m depth and considered as a potential refuge, have not yet been well studied experimentally under thermal stress. As mesophotic corals are also highly fluorescent, and fluorescence under heat stress is known to undergo change, we examined the involvement of fluorescence during heat-induced bleaching, by incorporating both high-and low-fluorescence morphs in our experiments. We collected colonies of the mesophotic coral Alveopora ocellata and subjected them to elevated temperatures in both winter and summer in controlled laboratory experiments. We followed their physiological response and their bleaching at a high sampling resolution (every 48 h following the temperature ramping period). We found that A. ocellata bleached after a short-term (14 days) thermal stress of ?4 °C above ambient sea temperature during the summer, but did not bleach during the winter despite the elevated temperature (?5 °C; max temperature of 32 °C and 28 °C, respectively). After experiencing temperatures higher than 29.5 °C, the peak summer temperature, the corals gradually lost their algal symbionts during the summer experiment, while exhibiting an increase in symbiont density during the winter experiment. A similar response was also observed in chlorophyll a concentration, host fluorescence intensity, and maximal quantum yield of PSII (F v /F m ). Throughout the experiments (in both seasons and treatments), the highfluorescence corals presented lower zooxanthellae densities, higher cellular chlorophyll a concentration, and up to sixfold higher fluorescence. The differences found between the two morphs suggest that fluorescence may be favorable under thermal stress, strengthening the possibility of using coral fluorescence as a noninvasive monitoring tool for early detection of bleaching. This demonstration of a bleaching process in a mesophotic coral indicates the vulnerability of MCEs to the increase, in recent decades, in the frequency and intensity of temperature anomalies.

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Section: Discussionsupporting

confidence: 89%

Experimental evidence of temperature-induced bleaching in two fluorescence morphs of a Red Sea mesophotic coral

et al. 2020

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“…In this study, we demonstrate that speed-FluorIS enables a fast imaging of fluorescence to study coral recruitment patterns over a broader range of depths and reef topographies than previous fluorescence methods (Figures 6, 7; Schmidt-Roach et al, 2008;Roth and Knowlton, 2009;Hsu et al, 2014;Zweifler et al, 2017;Ramesh et al, 2019), providing a standardized survey methodology that can be applied in different sites across the world. Solely based on the results of our survey (Figures 6B, 7B), it is difficult to estimate recruitment dynamics in the shallow and mesophotic reefs of Eilat and Bermuda, considering that coral recruitment greatly varies between seasons and years (Jouval et al, 2019, and references therein).…”

Section: Discussionmentioning

confidence: 83%

In situ Estimation of Coral Recruitment Patterns From Shallow to Mesophotic Reefs Using an Optimized Fluorescence Imaging System

et al. 2021

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Coral recruitment represents a key element for coral reef persistence and resilience in the face of environmental disturbances. Studying coral recruitment patterns is fundamental for assessing reef health and implementing appropriate management strategies in an era of climate change. The FluorIS system has been developed to acquire high resolution, wide field-of-view (FOV) in situ images of coral recruits fluorescence and has proven successful in shallow reef environments. However, up to now, its applicability to mesophotic coral ecosystems remains unknown due to the complexity of the system and the limited time available when working at mesophotic depth. In this study we optimized the FluorIS system by utilizing a single infrared-converted camera instead of the bulkier regular dual-camera system, substantially reducing the system complexity and significantly decreasing the acquisition time to an average of 10 s for a set of 3 images. Moreover, the speed-FluorIS system is much more economical, decreasing the cost of the full set-up by roughly 40% compared to the original dual-camera system. We tested the utility of the speed-FluorIS by surveying coral recruits across shallow and mesophotic reefs of the Red Sea (Gulf of Eilat) and Bermuda, two of the most northerly reefs in the world with markedly different substrate and topography, and demonstrate that the modified system enables fast imaging of fluorescence to study coral recruitment patterns over a broader range of depths and reef topographies than previous fluorescence methods. Our single-camera system represents a valuable, non-invasive and rapid underwater tool which will help standardize surveys and long-term monitoring of coral recruits, contributing to our understanding of these vital and delicate early life stages of corals.

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“…Chlorophyll concentrations are indicative of photo-acclimation, among other things, and green fluorescent proteins may, in addition to being a signal of tissue repair ( D’Angelo et al, 2012 ), contribute to photoprotection in corals; and thus, quantifying these concentrations can provide crucial information on the bleaching susceptibility or resistance of corals ( Salih et al, 2000 ; Kenkel et al, 2011 ; Roth and Deheyn, 2013 ). In addition, this imaging technique can also mark early signs of disease as well as help to detect coral juveniles thereby leading to more accurate assessment of coral reef health ( Treibitz et al, 2015 ; Ramesh et al, 2019 ).…”

Section: Resultsmentioning

confidence: 99%

Experimental Techniques to Assess Coral Physiology in situ Under Global and Local Stressors: Current Approaches and Novel Insights

et al. 2021

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Coral reefs are declining worldwide due to global changes in the marine environment. The increasing frequency of massive bleaching events in the tropics is highlighting the need to better understand the stages of coral physiological responses to extreme conditions. Moreover, like many other coastal regions, coral reef ecosystems are facing additional localized anthropogenic stressors such as nutrient loading, increased turbidity, and coastal development. Different strategies have been developed to measure the health status of a damaged reef, ranging from the resolution of individual polyps to the entire coral community, but techniques for measuring coral physiology in situ are not yet widely implemented. For instance, while there are many studies of the coral holobiont response in single or limited-number multiple stressor experiments, they provide only partial insights into metabolic performance under more complex and temporally and spatially variable natural conditions. Here, we discuss the current status of coral reefs and their global and local stressors in the context of experimental techniques that measure core processes in coral metabolism (respiration, photosynthesis, and biocalcification) in situ, and their role in indicating the health status of colonies and communities. We highlight the need to improve the capability of in situ studies in order to better understand the resilience and stress response of corals under multiple global and local scale stressors.

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A rapid in situ fluorescence census for coral reef monitoring

Cited by 8 publications

References 21 publications

Experimental evidence of temperature-induced bleaching in two fluorescence morphs of a Red Sea mesophotic coral

Experimental evidence of temperature-induced bleaching in two fluorescence morphs of a Red Sea mesophotic coral

In situ Estimation of Coral Recruitment Patterns From Shallow to Mesophotic Reefs Using an Optimized Fluorescence Imaging System

Experimental Techniques to Assess Coral Physiology in situ Under Global and Local Stressors: Current Approaches and Novel Insights

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