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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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A Framework for Identifying and Characterising Coral Reef “Oases” Against a Backdrop of Degradation

Abstract:

  1. Human activities have led to widespread ecological decline; however, the severity of degradation is spatially heterogeneous due to some locations resisting, escaping, or rebounding from disturbances.
  2. We developed a framework for identifying oases within coral reef regions using long‐term monitoring data. We calculated standardised estimates of coral cover (z‐scores) to distinguish sites that deviated positively from regional means. We also used the coefficient of variation (CV) of coral cover to quantify how oases varied temporally, and to distinguish among types of oases. We estimated “coral calcification capacity” (CCC), a measure of the coral community’s ability to produce calcium carbonate structures and tested for an association between this metric and z‐scores of coral cover.
  3. We illustrated our z‐score approach within a modelling framework by extracting z‐scores and CVs from simulated data based on four generalized trajectories of coral cover. We then applied the approach to time‐series data from long‐term reef monitoring programmes in four focal regions in the Pacific (the main Hawaiian Islands and Mo’orea, French Polynesia) and western Atlantic (the Florida Keys and St. John, US Virgin Islands). Among the 123 sites analysed, 38 had positive z‐scores for median coral cover and were categorised as oases.
  4. Synthesis and applications. Our framework provides ecosystem managers with a valuable tool for conservation by identifying “oases” within degraded areas. By evaluating trajectories of change in state (e.g., coral cover) among oases, our approach may help in identifying the mechanisms responsible for spatial variability in ecosystem condition. Increased mechanistic understanding can guide whether management of a particular location should emphasise protection, mitigation or restoration. Analysis of the empirical data suggest that the majority of our coral reef oases originated by either escaping or resisting disturbances, although some sites showed a high capacity for recovery, while others were candidates for restoration. Finally, our measure of reef condition (i.e., median z‐scores of coral cover) correlated positively with coral calcification capacity suggesting that our approach identified oases that are also exceptional for one critical component of ecological function.

Authors: J. R. Guest, P. J. Edmunds, R. D. Gates, I. D. Kuffner, A. J. Andersson, B. B. Barnes, I. Chollett, T. A. Courtney, R. Elahi, E. A. Lenz, S. Mitarai, P. J. Mumby, H. R. Nelson, B. A. Parker, H. M. Putnam, C. S. Rogers, L. T. Toth

Year: 2018
Download the open access article here

Journal of Applied Ecology pg. 1-11: doi.org/10.1111/1365-2664.13179 

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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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Plastic Waste Associated With Disease On Coral Reefs

Abstract: Plastic waste can promote microbial colonization by pathogens implicated in outbreaks of disease in the ocean. We assessed the influence of plastic waste on disease risk in 124,000 reef-building corals from 159 reefs in the Asia-Pacific region. The likelihood of disease increases from 4% to 89% when corals are in contact with plastic. Structurally complex corals are eight times more likely to be affected by plastic, suggesting that microhabitats for reef-associated organisms and valuable fisheries will be disproportionately affected. Plastic levels on coral reefs correspond to estimates of terrestrial mismanaged plastic waste entering the ocean. We estimate that 11.1 billion plastic items are entangled on coral reefs across the Asia-Pacific and project this number to increase 40% by 2025. Plastic waste management is critical for reducing diseases that threaten ecosystem health and human livelihoods.

Author: Lamb, J. B., B.L. Willis, E.A. Fiorenza, C.S. Couch, R. Howard, D.N. Rader, D. Harvell
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Email for the full article: resilience@tnc.org
Science 359(6374).

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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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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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A Guide to Assessing Coral Reef Resilience for Decision Support

Maintaining and restoring resilience is now a major focus of most coral reef managers around the world. A focus on resilience gives us options – and hope – in the face of new and often daunting challenges. Underpinning this is the fact that local actions can positively influence the future of coral reefs, despite powerful external forces like climate change.

As examples, coral recovery from disturbances in Bermuda and the Bahamas has been greater in recent decades than in other parts of the Caribbean. Differences in recovery rates in the Caribbean have been partially attributed to establishing and enforcing fishing regulations, especially on key herbivores such as parrotfish (Jackson et al. 2014).

Overall though, the application of resilience theory to management planning and the day-to-day business of coral reef management has been challenging. One of the key stumbling blocks has been the lack of a robust and easily implementable method for assessing coral reef resilience in a way that can inform marine spatial planning and help to prioritize the implementation of management strategies.

Our ability to assess relative resilience of coral reefs has advanced dramatically in recent years, and we are now at a point where a feasible and useful process can be recommended for use in environmental planning and management.

This Guide presents a 10-step process for completing a resilience assessment, putting into managers’ hands the means to assess, map and monitor coral reef resilience, and the means to identify and prioritize actions that support resilience in the face of climate change. The guidance presented here represents the culmination of over a decade of experience and builds on ideas first presented by West and Salm (2003), Obura and Grimsditch (2009), and McClanahan and coauthors (2012). The resilience assessment process described in the Guide has been applied by the author group in Australia, Florida, CNMI, Guam, Palau, Indonesia, the Cayman Islands, and US Virgin Islands and in many other reef locations by other groups.

This guide is first and foremost intended for the individuals in charge of commissioning, planning, leading or coordinating a resilience assessment. The Guide also provides a resource for ‘reef managers’ of all kinds, including decision-makers, environmental planners and managers in coral reef areas, with influence over pressures affecting coral reefs. Outreach coordinators and educators working in coral reef areas may also benefit from the Guide, and they can participate in parts of the resilience assessment process, but the Guide focuses on the needs of decision-makers and the scientists who support them.

Author: Maynard, J.A., P.A. Marshall, B. Parker, E. Mcleod, G. Ahmadia, R. van Hooidonk, S. Planes, G.J. Williams, L. Raymundo, R. Beeden, J. Tamelander
Year: 2017
View Full Article

ISBN No: 978-92-807-3650-2

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Connecting Palau’s Marine Protected Areas: A Population Genetics Approach to Conservation

(INTERNAL RIGHTS ONLY) Aerial view of Kmekumer, Rock Islands, Republic of Palau, Palau, Asia Pacific. Photo credit: © Jez O'Hare

Aerial view of Kmekumer, Rock Islands, in Palau. Photo © Jez O’Hare

Listen to our interview with author Dr. Annick Cros, researcher at the Hawaiian Institute of Marine Biology, as she shares highlights from her recent publication on connecting Palua’s marine protected areas and discusses how findings from this study can guide conservation strategies for coral reef managers. 

Click the play button below to hear the interview.


Interview Transcript

Reef Resilience (RR): Hello everyone, Reef Resilience is interviewing Dr. Annick Cros, researcher at the Hawaiian Institute of Marine Biology and today she will share highlights from her recent publication on connecting Palau’s marine protected areas.

Annick Cros (AC): Hi everybody, thanks for having me today.

RR: Great, thanks for joining us. So how does this paper challenge how we are currently designing MPA networks?

AC: This paper challenges old assumptions about larval dispersal and connectivity. Connectivity is the exchange of individuals between populations. It is one factor that shapes the size and composition of a population. It plays a key role in genetics because connectivity acts against speciation and it may bring key genetic diversity that allows for adaptation. In the marine world, adults don’t move much or not at all and most of the connectivity happens with the dispersal during the pelagic larval stage of organisms.

RR: What did you assume about this topic before your paper and what were some of the take home messages from your research?

AC: Well larvae are so small, they are difficult to track. For example, we assumed that the longer a larvae could survive in the water column, the further it would travel, dispersed by currents due to its small size. Therefore, we assumed that most dispersal took place at large scales of hundreds of kilometers. We also assumed that at a small scale, genetically, a population would be very homogeneous because the exchange would happen at larger scales so that we would see genetic diversity at large scales. However, more recently an increasing amount of research has shown that dispersal is happening at a much smaller scale than expected and that most larvae recruit close to home.

AC: In our paper, we use population genetics to study the dispersal of Acropora hyacinthus around the barrier reef of Palau, Micronesia to test some of these assumptions. And the reason why we selected Palau was because in 1998 it suffered from heavy mortality from bleaching, in particular the coral Acropora hyacinthus. Since then it has recovered and the colonies we observe on Palau today are the result of recent patterns of dispersal making it easier to understand what is happening. What we found is that the patches of Acropora hyacinthus separated by a few kilometers around Palau’s reef do not mix very much, there is little connectivity. Instead we find surprisingly high numbers of colonies related to each other over a few hundred meters, indicating that dispersal happens at a very small scale. 

RR: So how can research on larval dispersal guide effective conservation strategies for coral reef managers?

AC: Well what we found is that instead of having a homogenous reef we had a mosaic of genetically different patches of corals which reflects the diversity that could play a role in the resilience and resistance of corals. So to manage it is a challenge because it requires protection of the entire reef, leading to the need for a more comprehensive approach than an MPA to manage Palau’s reef.

Authors: Cros, A., R.J. Toonen, M.J. Donahue, and S.A. Karl
Year: 2017
View Abstract
Email for the full article: resilience@tnc.org

Coral Reefs: 1-14. doi: 10.1007/s00338-017-1565-x

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Western Indian Ocean Post-Bleaching Assessment Training

Watch on YouTube

July 21, 2017

Dr. David Obura and Mishal Gudka of CORDIO East Africa (supported through the Biodiversity Project of the Indian Ocean Commission) present a training on how to conduct a post-bleaching assessment in the Western Indian Ocean (WIO). This is part of a regional project in 6 WIO countries to assess the global impacts of the 2016 coral reef bleaching event. Contact mgudka@cordioea.net to learn more about the program.

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