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Learning from Reef Restoration Experiences Around the World Webcast

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July 17, 2018

Broadcast live from the Great Barrier Reef Restoration Symposium in Cairns, Australia, experts from around the globe share lessons learned from years working on coral restoration. From offshore coral nurseries, to restoration mitigation techniques, to climate change adaptation, this presentation session seeks to foster knowledge sharing and exchange between managers and practitioners across the globe.
 

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Local Management Actions Can Increase Coral Resilience to Thermally-Induced Bleaching

Abstract: Recent large-scale analyses suggest that local management actions may not protect coral reefs from climate change, yet most local threat-reduction strategies have not been tested experimentally. We show that removing coral predators is a common local action used by managers across the world, and that removing the corallivorous snail Coralliophila abbreviata from Caribbean brain corals (Pseudodiploria and Diploriaspecies) before a major warming event increased coral resilience by reducing bleaching severity (resistance) and post-bleaching tissue mortality (recovery). Our results highlight the need for increased evaluation and identification of local interventions that improve coral reef resilience.

Authors: E. C. Shaver, D. E. Burkepile, B. R. Silliman

Year: 2018

View the article here, or request a copy from lizcshaver@gmail.com

Nature Ecology & Evolution 2: doi.org/10.1038/s41559-018-0589-0

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Loss of coral reef growth capacity to track future increases in sea level

Abstract: Sea-level rise (SLR) is predicted to elevate water depths above coral reefs and to increase coastal wave exposure as ecological degradation limits vertical reef growth, but projections lack data on interactions between local rates of reef growth and sea level rise. Here we calculate the vertical growth potential of more than 200 tropical western Atlantic and Indian Ocean reefs, and compare these against recent and projected rates of SLR under different Representative Concentration Pathway (RCP) scenarios. Although many reefs retain accretion rates close to recent SLR trends, few will have the capacity to track SLR projections under RCP4.5 scenarios without sustained ecological recovery, and under RCP8.5 scenarios most reefs are predicted to experience mean water depth increases of more than 0.5 m by 2100. Coral cover strongly predicts reef capacity to track SLR, but threshold cover levels that will be necessary to prevent submergence are well above those observed on most reefs. Urgent action is thus needed to mitigate climate, sea-level and future ecological changes in order to limit the magnitude of future reef submergence.

Authors: C. T. Perry, L. Alvarez-Filip, N. A. Graham, P. J. Mumby, S. K. Wilson, P. S. Kench, D. P. Manzello, K. M. Morgan, A. B. A. Slangen, D. P. Thomson, F. Januchowski-Hartley, S. G. Smithers, R. S. Steneck, R. Carlton, E. N. Edinger, I. C. Enochs, N. Estrada-Saldivar, M. D. E. Haywood, G. Kolodziej, G. N. Murphy, E. Perez-Cervantes, A. Suchley, L. Valentino, R. Boenish, M. Wilson, C. Macdonald

Year: 2018
View the article here

Nature 558: doi.org/10.1038/s41586-018-0194-z

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Dispersal capacity and genetic relatedness in Acropora cervicornis on the Florida Reef Tract

Abstract: Sexual reproduction in scleractinian corals is a critical component of species recovery, fostering population connectivity and enhancing genetic diveristy. The relative contribution of sexual reproduction to both connectivity and diversity in Acropora cervicornis may be variable due to this species’ capacity to reproduce effectively by fragmentation. Using a biophysical model and genomic data in this threatened species, we construct potential connectivity pathways on the Florida Reef Tract (FRT) and compare them to inferred migration rates derived from next-generation sequencing, using a link and node-based approach. Larval connectivity on the FRT can be divided into two zones: the northern region, where most transport is unidirectional to the north with the Florida Current, and the southern region that is more dynamic and exhibits complex spatial patterns. These bihysical linkages are poorly correlated with genetic connectivity patterns, which resolve many reciprocal connections and suggest a less sparse network. These results are difficult to reconcile with genetic data which indicate that individual reefs are diverse, suggesting important contributions of sexual reproduction and recruitment. Larval connectivity models highlight potential resources for recovery, such as areas with high larval export like the Lower Keys, or areas that are well connected to most other regions on the FRT, such as the Dry Tortugas.

Authors: Drury, C., C. B. Paris, V. H. Kourafalou, and D. Lirman
Year: 2018
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Email for the full article: resilience@tnc.org

Coral Reefs 37: doi.org/10.1007/s00338-018-1683-0

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Impacts of Fragment Genotype, Habitat, and Size on Outplanted Elkhorn Coral Success Under Thermal Stress

Abstract: Active coral restoration through coral ‘gardening’ aims to remediate some of the drastic coral cover lost on Caribbean reefs, with increasing attention to the imperiled, iconic foundation species elkhorn coral Acropora palmata. We documented 2 experiments quantifying effects of A. palmata outplant characteristics and habitat on outplant success. Two thermal stress events (summer 2014 and 2015) occurred while the experiments were underway and thus lend insight into environmental interactions and coral restoration outcomes under projected thermal regimes. In the first experiment comparing 2 size classes of a single genotype, smaller fragments produced significantly more live tissue area, experienced less bleaching, and demonstrated equal survivorship compared to larger fragments. The second experiment compared 4 genotypes outplanted to both fore reef and mid-channel patch reef habitats. Genotypes varied significantly in survivorship, bleaching severity, and net change in size, with one (CN2g) performing well in all 3 metrics, and another (SLg) exhibiting poor survivorship, the most bleaching, and smaller changes in size. Overall, bleaching was less severe and survivorship less varied between genotypes in fore reef versus patch reef habitats. Fragments returned to the site of genotype origin did not consistently outperform ‘foreign’ genotypes from a different habitat type. Recognizing unique attributes associated with size and specific genotypes may improve the efficacy of active coral restoration in the face of future climate scenarios.

Author: Pausch, R. E., D.E. Williams, M.W. Miller
Year: 2018
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Email for the full article: resilience@tnc.org
Marine Ecology. doi:10.3354/meps12488

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Coral Reefs for Coastal Protection: A New Methodological Approach and Engineering Case Study in Grenada

Abstract: Coastal communities in tropical environments are at increasing risk from both environmental degradation and climate change and require urgent local adaptation action. Evidences show coral reefs play a critical role in wave attenuation but relatively little direct connection has been drawn between these effects and impacts on shorelines. Reefs are rarely assessed for their coastal protection service and thus not managed for their infrastructure benefits, while widespread damage and degradation continues. This paper presents a systematic approach to assess the protective role of coral reefs and to examine solutions based on the reef’s influence on wave propagation patterns. Portions of the shoreline of Grenville Bay, Grenada, have seen acute shoreline erosion and coastal flooding. This paper (i) analyzes the historical changes in the shoreline and the local marine, (ii) assess the role of coral reefs in shoreline positioning through a shoreline equilibrium model first applied to coral reef environments, and (iii) design and begin implementation of a reef-based solution to reduce erosion and flooding. Coastline changes in the bay over the past 6 decades are analyzed from bathymetry and benthic surveys, historical imagery, historical wave and sea level data and modeling of wave dynamics. The analysis shows that, at present, the healthy and well-developed coral reefs system in the southern bay keeps the shoreline in equilibrium and stable, whereas reef degradation in the northern bay is linked with severe coastal erosion. A comparison of wave energy modeling for past bathymetry indicates that degradation of the coral reefs better explains erosion than changes in climate and historical sea level rise. Using this knowledge on how reefs affect the hydrodynamics, a reef restoration solution is designed and studied to ameliorate the coastal erosion and flooding. A characteristic design provides a modular design that can meet specific engineering, ecological and implementation criteria. Four pilot units were implemented in 2015 and are currently being field-tested. This paper presents one of the few existing examples available to date of a reef restoration project designed and engineered to deliver risk reduction benefits. The case study shows how engineering and ecology can work together in community-based adaptation. Our findings are particularly important for Small Island States on the front lines of climate change, who have the most to gain from protecting and managing coral reefs as coastal infrastructure.

Author: Reguero, B. G., M.W. Beck, V.N. Agostini, P. Kramer, B. Hancock
Year: 2018
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Email for the full article: resilience@tnc.org
Journal of Environmental Management.

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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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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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Corals in Healthy Populations Produce More Larvae Per Unit Cover

Abstract: In coral reef conservation and management, the prevailing metric of reef health is percent coral cover, a measurement commonly used with the assumption that each
unit of live coral tissue has equivalent ecological value. Here we show that the
reproductive output of a coral population is not proportional to the cover of coral present.
Instead, when compared to declining populations nearby, high cover coral populations
produced up to four times more larvae per square centimeter of tissue, resulting in up to
200 times higher larval production per square meter of reef. Importantly, corals that
produced more larvae did not produce smaller larvae, as predicted by resource allocation
theory. Instead, higher fecundity corresponded to higher energetic lipid reserves in higher
cover coral populations. In the wake of unprecedented global coral bleaching, our
findings suggest that the largest reductions in coral reproduction may occur when corals
are lost from previously healthy populations.

Author: Hartmann, A.C., K.L Marhaver, M.J Vermeij
Year: 2017
View Abstract
http://onlinelibrary.wiley.com/doi/10.1111/conl.12410/full
Email for the full article: resilience@tnc.org

Conservation Letters. doi:10.1111/conl.12410

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Florida – Monitoring Reef Resilience


Coral Reef Resilience to Climate Change in the Florida Reef Tract

Location
Florida Reef Tract, Florida, USA

The Challenge
Climate change and a range of human activities threaten the natural resilience of coral reef ecosystems. Reef resilience is the ability to resist and recover from disturbances while retaining essentially the same function and structure. Managers can support the natural resilience of reefs by reducing their sensitivity to climate-related disturbances, such as coral bleaching, by reducing stress on reefs caused by human activities. Identifying resilient reef areas and better understanding their interaction with human stressors can help inform management strategies to better protect coral reefs in the future.

Southeast Florida’s coral reefs are located close to shore and co-exist with intensely urbanized areas. They are subject to impacts from a variety of natural and human stressors including, among others, coral bleaching and disease, invasive species, marine debris, land based sources of pollution, recreational and commercial misuse, and coastal construction. The challenge for natural resource managers in Florida, as with everywhere else reefs occur, lies in deciding which actions to implement and where, to best support resilience. Understanding spatial variation in resilience to climate change in the Florida Reef Tract was the goal of this project, with the aim being to produce information that can inform management decisions.

This project was a collaboration co-funded by NOAA’s Coral Reef Conservation Program, the Florida Department of Environmental Protection, and The Nature Conservancy’s Florida office. This project addresses this priority from Florida’s Climate Change Action Plan – Determine and map areas of high and low resilience to climate change in order to prioritize management efforts.

Actions Taken
Data Collection & Analysis
In order to understand the spatial variation in resilience to climate change in the Florida Reef Tract, the following seven indicators were included in the assessment of relative resilience:

  • coral cover
  • macroalgae cover
  • bleaching resistance
  • coral diversity
  • coral disease
  • herbivore biomass
  • temperature variability
Collecting data. Photo © Jessica Keller

Collecting data. Photo © Jessica Keller

Data used to develop these indicators come from field reef monitoring surveys (excepting temperature variability, which is remotely sensed) conducted in 2016 (no other years are included) as part of the National Coral Reef Monitoring Program and Florida Reef Resilience Program. Both monitoring programs use a stratified random sampling design whereby surveys are completed within all of the various habitat types and sub-regions of the Florida Reef Tract. A tutorial on analyzing relative resilience can be found here.

For this analysis, the data collected are summarized using weighted averages within ‘strata’, which combine habitat type and reef vertical complexity (i.e. ‘PR_HR’ Patch reef high relief in Tortugas). There are eight strata in Tortugas, seven in the Florida Keys (FL Keys) and eight in Southeast Florida (SE FL). A single value for each indicator is produced for each of these 23 strata. Indicator scores are then made uni-directional (high score is a good score), the scores are normalized to the maximum value to standardize scores to a 0-1 scale, and the scores are averaged and re-normalized to produce the final resilience scores. The strata are then ranked from highest to lowest score and classified as follows, based on the average (AVG) final resilience score (0.77) and standard deviation (SD) (0.16):

  • High (>AVG+1SD)
  • Med-high (>AVG & <AVG+1SD)
  • Med-low (<AVG & >AVG-1SD)
  • Low (<AVG-1SD)

Results
For the Florida Reef track sites, the average score for the ‘raw’ resilience scores was 0.5 and ranged from 0.31 to 0.65. The average of the normalized, final resilience scores was 0.77 and ranged from 0.31 to 0.65. The standard deviation around this average was 0.16. Relative resilience categories are set as:

  • High (>AVG+1SD; >0.93)
  • Med-high (>AVG & <AVG+1SD; >0.77&<0.93)
  • Med-low (<AVG & >AVG-1SD; <0.77&>0.61)
  • Low (<AVG-1SD; <0.61)
Figure 1. Relative resilience to climate change in the Florida Reef Tract, based on data collected in 2016. Rankings from highest to lowest relative resilience (1-23) are shown after strata codes top left, and descriptions for strata codes are right. Relative resilience is greatest in the FL Keys and lowest in SE Florida. Results of a canonical analysis of principal (CAP) coordinates are inset and show strong groupings among the relative categories in multivariate space. High resilience sites are strongly associated with high values for coral cover, bleaching resistance, and herbivore biomass and low levels of coral disease; the opposite is true for low resilience sites. (from Maynard et al. 2017)

Figure 1. Relative resilience to climate change in the Florida Reef Tract, based on data collected in 2016. Rankings from highest to lowest relative resilience (1-23) are shown after strata codes top left, and descriptions for strata codes are right. Relative resilience is greatest in the FL Keys and lowest in SE Florida. Results of a canonical analysis of principal (CAP) coordinates are inset and show strong groupings among the relative categories in multivariate space. High resilience sites are strongly associated with high values for coral cover, bleaching resistance, and herbivore biomass and low levels of coral disease; the opposite is true for low resilience sites (from Maynard et al. 2017). Click to see larger image.

Among the 23 strata, there are 5 with relatively high resilience, 9 medium-high, 6 medium-low, and 3 with relatively low resilience (Figure 1). The Tortugas had 1 high, 4 med-high, and 3 med-low resilience strata. The FL Keys had 4 high, 2 med-high, and 1 med-low resilience strata. SE Florida had 5 med-low and 3 low resilience strata.

The strata with relatively high resilience are:

  • F_D_LR [1] – Forereef deep low relief in FL Keys
  • MC_PR [2] – Mid-channel patch reef in FL Keys
  • PR_HR [3] – Patch reef high relief in Tortugas
  • RF_HR [4] – Reef high relief in FL Keys
  • F_M_LR [5] – Forereef mid-depth low relief in FL Keys

The strata with relatively low resilience are:

  • NEAR [21] – Nearshore in SE Florida
  • RR_C [22] – Reef-ridge complex in SE Florida
  • RF_D [23] – Reef deep in SE Florida

Results of a multivariate statistical analysis (canonical analysis of principal coordinates) results indicate that high resilience sites generally had high values for herbivore biomass, coral diversity, coral cover and bleaching resistance; the opposite is true for sites with medium-low or low resilience (Figure 1). Results are shared within a project report as maps and show spatial variation in relative resilience, as well as spatial variation in each of the 7 resilience indicators included in the analysis.

How successful has it been?
A better understanding of the spatial variation in resilience to climate change in the Florida Reef Tract was gained, which can now be used to inform management decisions. The maps of areas of high and low resilience to climate change will help to prioritize management efforts and decide which actions to implement and where, to best support resilience.

The project was successful in that the planned analysis was completed and report written, and the results were shared with collaborating managers from the Florida Department of Environmental Protection and the Florida Keys National Marine Sanctuary.

Lessons Learned and Recommendations
Future research and communication activities recommended include:

  • Compile past reef monitoring data to examine trends in resilience indicators and resilience over the last 10 years
  • Examine spatial variation in the resilience of other (than stony corals) key habitat builders, such as barrel sponges, sea fans and soft corals
  • Examine site-based data to review resilience at a higher-resolution than strata
  • Produce fact sheets to educate senior policy and decision-makers on resilience concepts
  • Use resilience information to predict survivorship of corals transplanted from nurseries
  • Develop a dashboard that makes reef monitoring data and resilience summaries available as interactive maps to managers and the public

Funding Summary
Funding for the project was provided by the Florida Department of Environmental Protection, the NOAA Coral Reef Conservation Program, and The Nature Conservancy

Lead Organizations
SymbioSeas and the Marine Applied Research Center
Florida Department of Environmental Protection
The Nature Conservancy
NOAA Coral Reef Conservation Program

Partners
Florida Keys National Marine Sanctuary
University of Miami RSMAS
NOAA Atlantic and Oceanographic Meteorological Laboratory

Resources
Assessing and Monitoring Reef Resilience
Coral Reef Resilience to Climate Change in the Florida Reef Tract (pdf, 3.5 M)

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