Antagonistic and synergistic responses to solar ultraviolet radiation and increased temperature of phytoplankton from cenotes (sink holes) of the Yucatán Peninsula, México

Cenotes (sink holes) are karstic formations characteristic of the Yucatán Peninsula and are the main source of fresh water in the region. Because of their tropical location, they receive high levels of solar radiation and are exposed to high temperatures. However, the effect of these global-change-related variables on phytoplankton in cenotes is unknown. We carried out experiments with phytoplankton communities collected from 2 cenotes differing in their penetration of solar radiation (Leona Vicario [LV]: turbid, Las Mojarras [LM]: clear) to assess the combined effect of solar ultraviolet radiation (UVR; 280–400 nm) and increased temperature on their photosystem (PS) II photochemistry. We exposed samples in microcosms to solar radiation (with and without UVR) and 2 temperatures (ambient = 25°C and increased by 3°C) and analyzed photochemical performance over daily cycles. A significant antagonistic interaction between UVR and temperature in LV caused a combined inhibition of the effective photochemical quantum yield (ΦPSII) that was smaller (63%) than the sum of the 2 individual effects of UVR and temperature (116%). In contrast, a significant synergistic interaction between UVR and temperature in LM caused the combined inhibition of ΦPSII (172%) to be higher than the sum of the individual effects of the 2 variables (134%). Differences in the size distribution and taxonomic composition of the phytoplankton communities, with smaller cells in LV than in LM, seem to account for much of the variability in responses to UVR and increased temperature between the 2 communities. Our results suggest that phytoplankton communities from clear cenotes will be more affected by the combined effects of solar UVR and increased temperature that those from turbid cenotes.Fil: Villafañe, Virginia Estela. Fundación Playa Unión. Estación de Fotobiología Playa Unión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Guendulain García, Sergio D.. Universidad Nacional Autónoma de México; MéxicoFil: Valadez, Francisco. Universidad Juárez Autónoma de Tabasco; México. Centro de Investigación Científica de Yucatán; MéxicoFil: Rosiles González, Gabriela. Centro de Investigación Científica de Yucatán; MéxicoFil: Helbling, Eduardo Walter. Fundación Playa Unión. Estación de Fotobiología Playa Unión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Banaszak, Anastazia T.. Universidad Nacional Autónoma de México; Méxic

Effects of Partial Mortality on Growth, Reproduction and Total Lipid Content in the Elkhorn Coral Acropora palmata

Partial mortality (PM) is increasingly common in the Elkhorn coral Acropora palmata and, depending on the causative agent, is potentially lethal. The effects of PM on growth, reproduction and total lipid content in A. palmata were studied by sampling apparently healthy (AH) colonies in comparison with colonies showing signs of PM. Branch growth rates and lesion regeneration rates were estimated using monthly photographs over a four-month period prior to the summer spawning season. No differences were found in the growth rates of colonies with PM compared to AH colonies. The areas affected by PM did not regenerate during the period of the study. Colonization of the lesions by competing species and sediment cover were documented and did not show major changes. During the spawning season, percent fertilization, egg volume and embryonic development were evaluated for comparison between AH colonies and those with PM. Total lipids were also quantified in tissues from three branches per colony. Percentage fertilization was similar in both AH colonies and those with PM. Embryonic development was normal, regardless of proximity to the lesion borders. However, egg volume was significantly lower in PM colonies than in AH colonies. Lower lipid concentrations were found at the edges of the lesions and similar to those found at the growing edges of the branches. The lack of regeneration may be explained by the low lipid concentration, because the polyps adjacent to the lesion do not have an adequate energy budget as a result of the damage. This would also affect their ability to compete against organisms that colonize the site of the lesion, a distinct situation to the rapid regeneration rates characteristic of lesions due to physical injury of the colony. Therefore, we conclude that partial mortality in A. palmata affects the colony, inducing energetic stress due to both competition and decreased egg quality

Light-driven dynamics between calcification and production in functionally diverse coral reef calcifiers

Coral reef metabolism underpins ecosystem function and is defined by the processes of photosynthesis, respiration, calcification, and calcium carbonate dissolution. However, the relationships between these physiological processes at the organismal level and their interactions with light remain unclear. We examined metabolic rates across a range of photosynthesising calcifiers in the Caribbean: the scleractinian corals Acropora cervicornis, Orbicella faveolata, Porites astreoides, and Siderastrea siderea, and crustose coralline algae (CCA) under varying natural light conditions. Net photosynthesis and calcification showed a parabolic response to light across all species, with differences among massive corals, branching corals, and CCA that reflect their relative functional roles on the reef. At night, all organisms were net respiring, and most were net calcifying, although some incubations demonstrated instances of net calcium carbonate (CaCO3) dissolution. Peak metabolic rates at light-saturation (maximum photosynthesis and calcification) and average dark rates (respiration and dark calcification) were positively correlated across species. Interspecies relationships among photosynthesis, respiration, and calcification indicate that calcification rates are linked to energy production at the organismal level in calcifying reef organisms. The species-specific ratios of net calcification to photosynthesis varied with light over a diurnal cycle. The dynamic nature of calcification/photosynthesis ratios over a diurnal cycle questions the use of this metric as an indicator for reef function and health at the ecosystem scale unless temporal variability is accounted for, and a new metric is proposed. The complex light-driven dynamics of metabolic processes in coral reef organisms indicate that a more comprehensive understanding of reef metabolism is needed for predicting the future impacts of global change

A roadmap to integrating resilience into the practice of coral reef restoration.

Recent warm temperatures driven by climate change have caused mass coral bleaching and mortality across the world, prompting managers, policymakers, and conservation practitioners to embrace restoration as a strategy to sustain coral reefs. Despite a proliferation of new coral reef restoration efforts globally and increasing scientific recognition and research on interventions aimed at supporting reef resilience to climate impacts, few restoration programs are currently incorporating climate change and resilience in project design. As climate change will continue to degrade coral reefs for decades to come, guidance is needed to support managers and restoration practitioners to conduct restoration that promotes resilience through enhanced coral reef recovery, resistance, and adaptation. Here, we address this critical implementation gap by providing recommendations that integrate resilience principles into restoration design and practice, including for project planning and design, coral selection, site selection, and broader ecosystem context. We also discuss future opportunities to improve restoration methods to support enhanced outcomes for coral reefs in response to climate change. As coral reefs are one of the most vulnerable ecosystems to climate change, interventions that enhance reef resilience will help to ensure restoration efforts have a greater chance of success in a warming world. They are also more likely to provide essential contributions to global targets to protect natural biodiversity and the human communities that rely on reefs

Editorial: Coral Reefs in the Anthropocene – Reflecting on 20 Years of Reef Conservation UK

Editorial on the Research Topic Coral Reefs in the Anthropocene – Reflecting on 20 Years of Reef Conservation UK.N

Six priorities to advance the science and practice of coral reef restoration worldwide

Coral reef restoration is a rapidly growing movement galvanized by the accelerating degradation of the world's tropical coral reefs. The need for concerted and collaborative action focused on the recovery of coral reef ecosystems coalesced in the creation of the Coral Restoration Consortium (CRC) in 2017. In March 2020, the CRC leadership team met for a biennial review of international coral reef restoration efforts and a discussion of perceived knowledge and implementation bottlenecks that may impair scalability and efficacy. Herein we present six priorities wherein the CRC will foster scientific advancement and collaboration to: (1) increase restoration efficiency, focusing on scale and cost-effectiveness of deployment; (2) scale up larval-based coral restoration efforts, emphasizing recruit health, growth, and survival; (3) ensure restoration of threatened coral species proceeds within a population-genetics management context; (4) support a holistic approach to coral reef ecosystem restoration; (5) develop and promote the use of standardized terms and metrics for coral reef restoration; and (6) support coral reef restoration practitioners working in diverse geographic locations. These priorities are not exhaustive nor do we imply that accomplishing these tasks alone will be sufficient to restore coral reefs globally; rather these are topics where we feel the CRC community of practice can make timely and significant contributions to facilitate the growth of coral reef restoration as a practical conservation strategy. The goal for these collective actions is to provide tangible, local-scale advancements in reef condition that offset declines resulting from local and global stressors including climate change

Building consensus around the assessment and interpretation of Symbiodiniaceae diversity

Within microeukaryotes, genetic variation and functional variation sometimes accumulate more quickly than morphological differences. To understand the evolutionary history and ecology of such lineages, it is key to examine diversity at multiple levels of organization. In the dinoflagellate family Symbiodiniaceae, which can form endosymbioses with cnidarians (e.g., corals, octocorals, sea anemones, jellyfish), other marine invertebrates (e.g., sponges, molluscs, flatworms), and protists (e.g., foraminifera), molecular data have been used extensively over the past three decades to describe phenotypes and to make evolutionary and ecological inferences. Despite advances in Symbiodiniaceae genomics, a lack of consensus among researchers with respect to interpreting genetic data has slowed progress in the field and acted as a barrier to reconciling observations. Here, we identify key challenges regarding the assessment and interpretation of Symbiodiniaceae genetic diversity across three levels: species, populations, and communities. We summarize areas of agreement and highlight techniques and approaches that are broadly accepted. In areas where debate remains, we identify unresolved issues and discuss technologies and approaches that can help to fill knowledge gaps related to genetic and phenotypic diversity. We also discuss ways to stimulate progress, in particular by fostering a more inclusive and collaborative research community. We hope that this perspective will inspire and accelerate coral reef science by serving as a resource to those designing experiments, publishing research, and applying for funding related to Symbiodiniaceae and their symbiotic partnerships.journal articl

Environmental plastics in the context of UV radiation, climate change, and the Montreal Protocol

There are close links between solar UV radiation, climate change, and plastic pollution. UV-driven weathering is a key process leading to the degradation of plastics in the environment but also the formation of potentially harmful plastic fragments such as micro- and nanoplastic particles. Estimates of the environmental persistence of plastic pollution, and the formation of fragments, will need to take in account plastic dispersal around the globe, as well as projected UV radiation levels and climate change factors. UV radiation, climate change, and plastic pollution are closely interlinked. Existing studies on the persistence of plastics do not fully consider these linkages, challenging global assessments of plastic dispersal, persistence, and weathering. Recently, an Intergovernmental Negotiating Committee was tasked with developing an international binding agreement to end plastic pollution. In response, the UNEP Environmental Effects Assessment Panel assessed effects of UV radiation and interacting climate change factors on plastics, focusing on the durability of products as well as the production and dispersal of micro- and nano-plastic pollutants in the environment

Building consensus around the assessment and interpretation of Symbiodiniaceae diversity

Within microeukaryotes, genetic variation and functional variation sometimes accumulate more quickly than morphological differences. To understand the evolutionary history and ecology of such lineages, it is key to examine diversity at multiple levels of organization. In the dinoflagellate family Symbiodiniaceae, which can form endosymbioses with cnidarians (e.g., corals, octocorals, sea anemones, jellyfish), other marine invertebrates (e.g., sponges, molluscs, flatworms), and protists (e.g., foraminifera), molecular data have been used extensively over the past three decades to describe phenotypes and to make evolutionary and ecological inferences. Despite advances in Symbiodiniaceae genomics, a lack of consensus among researchers with respect to interpreting genetic data has slowed progress in the field and acted as a barrier to reconciling observations. Here, we identify key challenges regarding the assessment and interpretation of Symbiodiniaceae genetic diversity across three levels: species, populations, and communities. We summarize areas of agreement and highlight techniques and approaches that are broadly accepted. In areas where debate remains, we identify unresolved issues and discuss technologies and approaches that can help to fill knowledge gaps related to genetic and phenotypic diversity. We also discuss ways to stimulate progress, in particular by fostering a more inclusive and collaborative research community. We hope that this perspective will inspire and accelerate coral reef science by serving as a resource to those designing experiments, publishing research, and applying for funding related to Symbiodiniaceae and their symbiotic partnerships