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Coral Reefs Will Transition to Net Dissolving Before End of Century

Abstract: Ocean acidification refers to the lowering of the ocean’s pH due to the uptake of anthropogenic CO2 from the atmosphere. Coral reef calcification is expected to decrease as the oceans become more acidic. Dissolving calcium carbonate (CaCO3) sands could greatly exacerbate reef loss associated with reduced calcification but is presently poorly constrained. Here we show that CaCO3 dissolution in reef sediments across five globally distributed sites is negatively correlated with the aragonite saturation state (Ωar) of overlying seawater and that CaCO3 sediment dissolution is 10-fold more sensitive to ocean acidification than coral calcification. Consequently, reef sediments globally will transition from net precipitation to net dissolution when seawater Ωarreaches 2.92 ± 0.16 (expected circa 2050 CE). Notably, some reefs are already experiencing net sediment dissolution.

Author: Eyre, B. D., T. Cyronak, P. Drupp, E.H. Carlo, J.P. Sachs, A.J. Andersson
Year: 2018
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Science. doi:10.1126/science.aao1118

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A Potential Method for Improving Coral Self-Attachment

Abstract: Coral restoration is becoming increasingly important to sustain declining reefs. The survival rate of translocated corals in restoration projects is around 65%. This rate is, however, highly variable among projects, with success ranging from 0 to 90% and with detachment being a significant cause of mortality. Improving the speed and strength of coral self-attachment would increase survivorship in translocated corals. To address this need, we tested whether fragments of the scleractinian coral, Hydnophora rigida, artificially attached upside-down would self-attach more rapidly to the substratum than those artificially attached the right way up, which is the normal practice. We also tested the effect of three different diets (unfed, normal Artemia, and lipid-enriched Artemia) on coral growth and other biological responses. After 100 days, our results demonstrated that corals fixed upside-down grew significantly wider and faster over the substratum than corals fixed the right way up. A significantly higher number of fragments fixed upside-down were also able to self-attach and grow over the substratum (87%) compared with fragments fixed the right way up (58%). Neither the buoyant weight, height increment, symbiont density, chlorophyll, maximum quantum yield nor colour of corals fixed upside-down differed significantly from corals fixed the right way up. Our data shows that simply inverting the orientation of coral fragments may substantially accelerate the time for self-attachment and increase the survival rate of translocated corals in restoration projects.

Author: Tagliafico, A., S. Rangel, L. Christidis, B.P. Kelaher
Year: 2018
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Restoration Ecology. doi:10.1111/rec.12698

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The Use of Larvae Or Recruits in Coral Restoration Initiatives: Symbiodinium Acquisition Does Not Differ Between Coral Life Stages In the Wild

Abstract: Active restoration initiatives are increasingly considered in natural resource management. Laboratory reared coral larvae and recruits have been proposed for stock production but it is unknown if their use impacts subsequent symbiosis once transplanted to the reef. We exposed laboratory and field settled aposymbiotic recruits (recently settled < 1 month) to Symbiodinium in the wild, then analysed the acquired communities using ITS-2 sequencing. There was no significant difference between treatments based on overall community and diversity metrics, or differential abundance of individual taxa. These results suggest that early acquisition is analogous and thus supports the use of either life-stage as an option for reef restoration.

Author: Quigley, K. M., G. Torda, L.K Bay
Year: 2018
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Restoration Ecology. doi:10.1111/rec.12695

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Climate Change Promotes Parasitism In a Coral Symbiosis

Abstract: Coastal oceans are increasingly eutrophic, warm and acidic through the addition of anthropogenic nitrogen and carbon, respectively. Among the most sensitive taxa to these changes are scleractinian corals, which engineer the most biodiverse ecosystems on Earth. Corals’ sensitivity is a consequence of their evolutionary investment in symbiosis with the dinoflagellate alga, Symbiodinium. Together, the coral holobiont has dominated oligotrophic tropical marine habitats. However, warming destabilizes this association and reduces coral fitness. It has been theorized that, when reefs become warm and eutrophic, mutualistic Symbiodinium sequester more resources for their own growth, thus parasitizing their hosts of nutrition. Here, we tested the hypothesis that sub-bleaching temperature and excess nitrogen promotes symbiont parasitism by measuring respiration (costs) and the assimilation and translocation of both carbon (energy) and nitrogen (growth; both benefits) within Orbicella faveolata hosting one of two Symbiodiniumphylotypes using a dual stable isotope tracer incubation at ambient (26 °C) and sub-bleaching (31 °C) temperatures under elevated nitrate. Warming to 31 °C reduced holobiont net primary productivity (NPP) by 60% due to increased respiration which decreased host %carbon by 15% with no apparent cost to the symbiont. Concurrently, Symbiodinium carbon and nitrogen assimilation increased by 14 and 32%, respectively while increasing their mitotic index by 15%, whereas hosts did not gain a proportional increase in translocated photosynthates. We conclude that the disparity in benefits and costs to both partners is evidence of symbiont parasitism in the coral symbiosis and has major implications for the resilience of coral reefs under threat of global change.

Author: Baker, D. M., C.J. Freeman, J.C. Wong, M.L. Fogel, N. Knowlton
Year: 2018
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The ISME Journal. doi:10.1038/s41396-018-0046-8

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De Novo Assembly and Annotation of The Acropora gemmifera Transcriptome

Abstract: Stony corals from the genus Acropora are widely distributed, important reef-builders and have become increasingly utilized for investigating links between genetics and spawning behaviour. We assembled and annotated a composite transcriptome from Acropora gemmifera using Illumina HiSeq2500 analysis of two libraries from different lunar and solar phases to identify genes that have potential functional roles in reproductive-related traits. A total of 31.6 million combined raw reads were assembled using Trinity and built into 104,000 contigs. Functional gene annotation was performed using dammit, Gene Ontology (GO), KOG (WebMGA) and KEGG pathway analyses (Kaas). This resource will be valuable for researchers studying gene expression patterns in coral reproductive cycles and evolution of the genus Acropora.

Author: Oldach, M. J., P.D. Vize
Year: 2018
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Email for the full article: resilience@tnc.org
Marine Genomics. doi:10.1016/j.margen.2017.12.007

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Effects of thermal stress and nitrate enrichment on the larval performance of two Caribbean reef corals

Abstract: The effects of multiple stressors on the early life stages of reef-building corals are poorly understood. Elevated temperature is the main physiological driver of mass coral bleaching events, but increasing evidence suggests that other stressors, including elevated dissolved inorganic nitrogen (DIN), may exacerbate the negative effects of thermal stress. To test this hypothesis, we investigated the performance of larvae of Orbicella faveolata and Porites astreoides, two important Caribbean reef coral species with contrasting reproductive and algal transmission modes, under increased temperature and/or elevated DIN. We used a fluorescence-based microplate respirometer to measure the oxygen consumption of coral larvae from both species, and also assessed the effects of these stressors on P. astreoides larval settlement and mortality. Overall, we found that (1) larvae increased their respiration in response to different factors (O. faveolata in response to elevated temperature and P. astreoides in response to elevated nitrate) and (2) P. astreoides larvae showed a significant increase in settlement as a result of elevated nitrate, but higher mortality under elevated temperature. This study shows how microplate respirometry can be successfully used to assess changes in respiration of coral larvae, and our findings suggest that the effects of thermal stress and nitrate enrichment in coral larvae may be species specific and are neither additive nor synergistic for O. faveolata or P. astreoides. These findings may have important consequences for the recruitment and community reassembly of corals to nutrient-polluted reefs that have been impacted by climate change.

Author: Serrano, X. M., M.W.Miller, J.C. Hendee, B.A. Jensen, J.Z. Gapayao, C. Pasparakis, A.C Baker
Year: 2017
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Coral Reefs 37(1). doi:10.1007/s00338-017-1645-y

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Ice Volume and Climate Changes From a 6000 Year Sea-level Record in French Polynesia

Abstract: Mid- to late-Holocene sea-level records from low-latitude regions serve as an important baseline of natural variability in sea level and global ice volume prior to the Anthropocene. Here, we reconstruct a high-resolution sea-level curve encompassing the last 6000 years based on a comprehensive study of coral microatolls, which are sensitive low-tide recorders. Our curve is based on microatolls from several islands in a single region and comprises a total of 82 sea-level index points. Assuming thermosteric contributions are negligible on millennial time scales, our results constrain global ice melting to be 1.5–2.5 m (sea-level equivalent) since ~5500 years before present. The reconstructed curve includes isolated rapid events of several decimetres within a few centuries, one of which is most likely related to loss from the Antarctic ice sheet mass around 5000 years before present. In contrast, the occurrence of large and flat microatolls indicates periods of significant sea-level stability lasting up to ~300 years.

Author: Hallmann, N., G. Camoin, A. Eisenhauer, A. Botella, G.A. Milne, C. Vella, J. Fietzke
Year: 2018
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Email for the full article: resilience@tnc.org
Nature Communications 9(1). doi:10.1038/s41467-017-02695-7

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Bleaching Events Regulate Shifts From Corals to Excavating Sponges in Algae-dominated Reefs

Abstract: Changes in coral–sponge interactions can alter reef accretion/erosion balance and are important to predict trends on current algal-dominated Caribbean reefs. Although sponge abundance is increasing on some coral reefs, we lack information on how shifts from corals to bioeroding sponges occur, and how environmental factors such as anomalous seawater temperatures and consequent coral bleaching and mortality influence these shifts. A state transition model (Markov chain) was developed to evaluate the response of coral-excavating sponges (Cliona delitrix Pang 1973) after coral bleaching events. To understand possible outcomes of the sponge–coral interaction and build the descriptive model, sponge–corals were monitored in San Andres Island, Colombia (2004–2011) and Fort Lauderdale, Florida (2012–2013). To run the model and determine possible shifts from corals to excavating sponges, 217 coral colonies were monitored over 10 years (2000–2010) in Fort Lauderdale, Florida, and validated with data from 2011 to 2015. To compare and test its scalability, the model was also run with 271 coral colonies monitored in St. Croix, US Virgin Islands over 7 years (2004–2011), and validated with data from 2012 to 2015. Projections and sensitivity analyses confirmed coral recruitment to be key for coral persistence. Excavating sponge abundance increased in both Fort Lauderdale and St. Croix reefs after a regional mass bleaching event in 2005. The increase was more drastic in St. Croix than in Fort Lauderdale, where 25% of the healthy corals that deteriorated were overtaken by excavating sponges. Projections over 100 years suggested successive events of coral bleaching could shift algae–coral dominated reefs into algae–sponge dominated. The success of excavating sponges depended on the intensity of coral bleaching and consequent coral mortality. Thus, the proportion of C. delitrix excavating sponges is a sensitive indicator for the intensity and frequency of recent disturbance on Caribbean coral reefs.

Author: Chaves-Fonnegra, A., B. Riegl, S. Zea, J.V. Lopez, T. Smith, M. Brandt, D.S.Gilliam
Year: 2017
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Email for the full article: resilience@tnc.org
Global Change Biology 24(2). doi:10.1111/gcb.13962

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Year in Review – 2017

Reflecting on the past year, there has never been a more critical time for effective coral reef management. In June of 2017, the world’s longest and most widespread bleaching event on record ended, with many reefs experiencing significant mortality. To address these – and other – challenges, the Reef Resilience Network continues to empower a global network of marine managers and scientists to improve coral reef management by sharing and implementing cutting-edge resilience science, inspiring greater collaboration, and working with global and regional reef initiatives to roll out guidance and best practices. Based on feedback from our managers, we have led in-person and online trainings, and have added new webinars, case studies, journal summaries, guidebooks, and modules on key topics to our website, reefresilience.org, which had over 150,000 visitors this year alone!

We are inspired by the thousands of reef managers, practitioners, and scientists in our Network and beyond, who spend their days working to reduce the threats facing reefs and supporting the necessary policies and programs to help our reefs to recover and thrive. We thank you and look forward and ahead to 2018 – the International Year of the Reef – and are grateful for the renewed attention to one of our world’s most precious resources, our coral reefs. See how we, as a Network, have improved reef management around the world.

RR Year in Review 2017_final

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Strategic Communication Mentored Online Course

Comm AnnJanuary 16 – February 8, 2018

Looking to influence behavior or raise awareness about an issue to advance your conservation efforts? A new Strategic Communication Mentored Online Course can help you communicate effectively to reach your conservation goal! This three-week mentored training, which is only a 6-8 hour time commitment, features hands-on exercises, interactive webinars and quizzes, and guidance from mentors and other managers. We’ve demystified strategic communication and simplified the planning process so you can work on your own project as you learn. This course is free and open to anyone, but is geared toward coral reef managers and practitioners. The course content can be found in the communication module.

Important Dates:

  • December 18 – January 16: Course registration is open. Registration closes January 17
  • January 16: Course orientation and introductory webinar (45 minutes)
  • January 17 – January 24: Complete three self-paced lessons and worksheets on the communication planning process: establish your goal & objectives, assess the context for your efforts, and identify your target audience(s) (~2.5 hours)
  • January 25: Webinar 2 – Review concepts and discussion (45 minutes)
  • January 26 – February 7: Complete four self-paced lessons and worksheets on the communication planning process: make your message matter, identify messengers and tactics, measure your impact, and create a summary of your plan (~3.5 hours)
  • February 8: Webinar 3 – Review concepts, discussion, and course conclusion (30 minutes)
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