A comparison of photographic analyses used to quantify zooxanthella density and pigment concentrations in Cnidarians

Johnson, Cameron; Goulet, Tamar L.

doi:10.1016/j.jembe.2007.10.003

Cited by 11 publications

(3 citation statements)

References 39 publications

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“…The average pixel intensities of the fragments were measured as a proxy for their chlorophyll content and symbiodinium density (cf. [ 30 , 31 ]), and an increase in the average pixel intensities was regarded as a loss of chlorophyll or symbiodinium cells. Hence, the change in the fragments’ average pixel intensities over the course of the experiment denoted the bleaching intensity.…”

Section: Methodsmentioning

confidence: 99%

Acute Toxicity Assays with Adult Coral Fragments: A Method for Standardization

Brefeld,

Di Mauro,

Kellermann

et al. 2023

Toxics

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Coral reefs are globally declining due to various anthropogenic stressors. Amongst those, chemical pollutants, such as pesticides from agricultural runoff, sewage or an overabundance of personal care products in coastal waters due to intense tourism, may be considered as a local stressor for reef-building corals. The extent to which such chemicals exhibit toxic effects towards corals at environmentally relevant concentrations is currently controversially discussed and existing studies are often based on varying and sometimes deficient test methods. To address this uncertainty, we adapted available methods into a reliable and comprehensive acute coral toxicity test method for the reef-building coral Montipora digitata. The toxicities of the four substances benzophenone-3 (BP-3), Diuron (DCMU), copper (Cu2+ as CuCl2, positive control) and dimethylformamide (DMF, solvent) were assessed in a 96 h semi-static test design. Endpoints such as maximum quantum yield, bleaching, tissue loss and mortality were evaluated with respect to their suitability for regulatory purposes. Overall, the endpoints bleaching and mortality yielded sensitive and robust results for the four tested substances. As the test method follows the principles of internationally standardized testing methods (ISO, OECD), it can be considered suitable for further validation and standardization. Once validated, a standardized test method will help to obtain reproducible toxicity results useful for marine hazard and risk assessment and regulatory decision making.

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Section: Methodsmentioning

confidence: 99%

Acute Toxicity Assays with Adult Coral Fragments: A Method for Standardization

Brefeld,

Di Mauro,

Kellermann

et al. 2023

Toxics

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“…Coral cells can lose the Symbiodiniaceae cells within them, or, the stressor may lead to loss of coral cells, and since the host cells contain Symbiodiniaceae, the end result is that the coral has less Symbiodiniaceae within it. The common approach of assessing Symbiodiniaceae density (Fitt et al, 2000;Siebeck et al, 2006;Johnson and Goulet, 2007) does not address the two scenarios. Conversely, quantifying both algal and host parameters can illuminate the route to the bleaching outcome.…”

Section: A Holistic Approach Requires Assessing Parameters Of As Manymentioning

confidence: 99%

Conceptualization of the Holobiont Paradigm as It Pertains to Corals

et al. 2020

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Corals' obligate association with unicellular dinoflagellates, family Symbiodiniaceae form the foundation of coral reefs. For nearly a century, researchers have delved into understanding the coral-algal mutualism from multiple levels of resolution and perspectives, and the questions and scope have evolved with each iteration of new techniques. Advances in genetic technologies not only aided in distinguishing between the multitude of Symbiodiniaceae but also illuminated the existence and diversity of other organisms constituting the coral microbiome. The coral therefore is a meta-organism, often referred to as the coral holobiont. In this review, we address the importance of including a holistic perspective to understanding the coral holobiont. We also discuss the ramifications of how different genotypic combinations of the coral consortium affect the holobiont entity. We highlight the paucity of data on most of the coral microbiome. Using Symbiodiniaceae data, we present evidence that the holobiont properties are not necessarily the sum of its parts. We then discuss the consequences of the holobiont attributes to the fitness of the holobiont and the myriad of organisms that contribute to it. Considering the complexity of host-symbiont genotypic combinations will aid in our understanding of coral resilience, robustness, acclimation, and/or adaptation in the face of environmental change and increasing perturbations.

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“…When a reef is observed by scuba or snorkel diving, several methods are in use, such as the visual assessment of coral colour compared to a colour scale on a reference card (Siebeck et al 2006), or photographic assessment (Johnson and Goulet 2007;Winters et al 2009). In aquaria experiments on pieces of live coral, bleaching is usually measured as a statistically significant decline in Symbiodinium cell density and/or chlorophyll content (per unit area or per symbiont cell).…”

Section: Research Involving Human or Animal Subjectsmentioning

confidence: 99%

Coral responses to temperature, irradiance and acidification stress: linking physiology to satellite remote sensing

Mason¹

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The success of the symbiosis of scleractinian corals with dinoflagellates of the genus Symbiodinium is highly dependent on the availability of sufficient, but not excess, light for photosynthesis. After decades of fundamental research into the effect of light on the coral-dinoflagellate symbiosis, an important practical application is emerging in remote monitoring of bleaching at coral reefs. Coral bleaching that originates with the dysfunction of photosynthesis can be either photoacclimatory, a controlled adjustment in response to environmental change, or it can be associated with photodamage, an uncontrolled response to environmental change. It is the latter that tends to lead to severe bleaching events that decrease the rate of carbon fixation, generate excessive oxygen radicals and may ultimately lead to coral death if unfavourable conditions persist. Current best practice methods for the prediction of coral bleaching use water temperature as detected via satellite, and predict the onset of coral bleaching accurately, but not the percent of corals bleached at a reef or the extent of the ensuing mortality.Due to its central role in causing photodamage, the use of light level (in addition to temperature) as a predictive variable may improve the accuracy of predictions of coral bleaching severity. The rate of photoacclimation affects the duration of elevated stress following an increase or decrease in incident light level and so it is potentially important for predicting the severity of coral bleaching.As coral reef management practitioners aim to predict bleaching and bleaching-induced mortality at entire reef locales, which are typically composed of a multi-species coral community, differences in coral physiological responses are of importance in designing accurate prediction methods. The interaction of high light and high temperature with a third stressor, ocean acidification, may influence coral bleaching, as ocean acidification changes oceanic chemical parameters that are key to cellular mechanisms of homeostasis and to dinoflagellate photosynthesis.Using multiple-stressor aquarium experiments, I investigated the photoacclimation rate in corals, differences in response to light and temperature stress among coral species, and the interaction of light, temperature and ocean acidification on coral bleaching onset and severity (at the colony scale). My investigation of photoacclimation (via 24 days of exposure to a large increase, a moderate increase, and a large decrease in light) in Acropora muricata and mounding Porites spp.indicated that the direction of light change and the water temperature influenced photoacclimation duration. However, the exact patterns were specific to the variable used to measure photoacclimation (for instance, changes in net areal photosynthesis, or changes in quantum 2 efficiency of photosystem II), with important ramifications for the development of a combined light and temperature bleaching prediction method.I investigated species-specific physiological responses in A. mu...

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A comparison of photographic analyses used to quantify zooxanthella density and pigment concentrations in Cnidarians

Cited by 11 publications

References 39 publications

Acute Toxicity Assays with Adult Coral Fragments: A Method for Standardization

Acute Toxicity Assays with Adult Coral Fragments: A Method for Standardization

Conceptualization of the Holobiont Paradigm as It Pertains to Corals

Coral responses to temperature, irradiance and acidification stress: linking physiology to satellite remote sensing

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