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Response of a Fringing Reef Coastline to the Direct Impact of a Tropical Cyclone

Abstract: Tropical cyclones generate extreme hazards along coastlines, often leading to losses of life and property. Although coral reefs exist in cyclone-prone regions globally, few studies have measured the hydrodynamic conditions and morphological responses of reef-fringed coastlines to tropical cyclones. Here, we examine the impact of Tropical Cyclone Olwyn on a section of Australia’s largest fringing reef (Ningaloo Reef) using in situ wave and water level observations, topographic surveys, and numerical modeling. Despite forereef significant wave heights reaching 6 m and local winds of 140 km h-1, average beach volume change was only -3 mm-1. The results indicate that this erosion was due to locally generated wind waves within the lagoon rather than the offshore waves that were dissipated on the reef crest. A comparison of these volume changes to observations of tropical cyclone impacts along exposed sandy beaches quantitatively demonstrates the substantial coastal protection reefs can provide against extreme storms.

Authors: Cuttler, M. V., J.E. Hansen, R.J. Lowe, and E.J. Drost
Year: 2018
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Limnology and Oceanography Letters 3(2). https://doi.org/10.1002/lol2.10067

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Nudging Pro-Environmental Behavior: Evidence and Opportunities

Abstract: Human behavior is responsible for many of our greatest environmental challenges. The accumulated effects of many individual and household decisions have major negative impacts on biodiversity and ecosystem health. Human behavioral science blends psychology and economics to understand how people respond to the context in which they make decisions (e.g., who presents the information and how it is framed). Behavioral insights have informed new strategies to improve personal health and financial choices. However, less is known about whether and how these insights can encourage choices that are better for the environment. We review 160 experimental interventions that attempt to alter behavior in six domains in which decisions have major environmental impacts: family planning, land management, meat consumption, transportation choices, waste production, and water use. The evidence suggests that social influence and simple adjustments to decision settings can influence pro- environmental decisions. We identify four important gaps in the evidence that provide opportunities for future research. To address these gaps, we encourage collaborations between researchers and practitioners that look at the effects of embedding tests of behavior-change interventions within environmental programs.

Authors: Byerly, H., A. Blamford, P.J. Ferraro, C.H. Wagner, E. Palchak, S. Polansky, et. al
Year: 2018
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Frontiers in Ecology and the Environment 16(3): 159-168, doi: 10.1002/fee.1777

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Harnessing Ecological Processes to Facilitate Coral Restoration

Abstract: Incorporating ecological processes into restoration planning is increasingly recognized as a fundamental component of successful restoration strategies. We outline a scientific framework to advance the emerging field of coral restoration. We advocate for harnessing ecological processes that drive community dynamics on coral reefs in a way that facilitates the establishment and growth of restored corals. Drawing on decades of coral reef ecology research and lessons learned from the restoration of other ecosystems, we posit that restoration practitioners can control factors such as the density, diversity, and identity of transplanted corals; site selection; and transplant design to restore positive feedback processes – or to disrupt negative feedback processes – in order to improve restoration success. Ultimately, we argue that coral restoration should explicitly incorporate key natural processes to exploit dynamic ecological forces and drive recovery of coral reef ecosystems.

Authors: Ladd, M. C., M.W. Miller, J.H. Hunt, W.C. Sharp, and D.E. Burkepile
Year: 2018
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Email for the full article: resilience@tnc.org

Ecological Society of America 16(4): doi:10.1002/fee.1792

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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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Email for the full article: resilience@tnc.org
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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Email for the full article: resilience@tnc.org
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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Email for the full article: resilience@tnc.org
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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Email for the full article: resilience@tnc.org
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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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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Email for the full article: resilience@tnc.org
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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