Archives

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
View More
Email for the full article: resilience@tnc.org
The ISME Journal. doi:10.1038/s41396-018-0046-8

Share on FacebookTweet about this on TwitterEmail this to someone

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
View More
Email for the full article: resilience@tnc.org
Coral Reefs 37(1). doi:10.1007/s00338-017-1645-y

Share on FacebookTweet about this on TwitterEmail this to someone

Spatial and Temporal Patterns of Mass Bleaching of Corals In The Anthropocene.

Abstract:Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.

Author: Hughes, T. P., K.D. Anderson, S.R. Connolly, S.F. Heron, J.T. Kerry, J.M. Lough, S.K. Wilson
Year 2018
View More
Email for the full article: resilience@tnc.org
Science Mag 359(6371). doi:10.1126/science.aan8048

Share on FacebookTweet about this on TwitterEmail this to someone

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)

Share on FacebookTweet about this on TwitterEmail this to someone

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

Share on FacebookTweet about this on TwitterEmail this to someone

Assisted Evolution: A Novel Tool to Overcome the Conservation Crisis?

Assisted Evolution Announcement PhotoThis symposium was live streamed as part of the Coral Restoration Consortium webinar series in conjunction with The Geomar Helmholtz Centre for Ocean Research Kiel and “The Future Ocean” cluster in Kiel. Speakers shared information on new approaches for the conservation of coral reefs such as assisted colonization and assisted evolution and synthetic biology. View the presentation recordings below.

Presentations:

Welcome and introduction – Marlene Wall, Geomar, Germany

Session 1: Shifting paradigms in conservation: social, public and scientific landscape of conservation genetics
Objective: The aim of session 1 is to (i) discuss new approaches for the conservation of natural environments, such as assisted colonization, assisted evolution and synthetic biology and (ii) introduce the current legal, public and scientific framework of novel methods in conservation.

Session 2: Assisted evolution in corals: Opportunities, applications, challenges, and limitations
Objective: The aim is to introduce how assisted evolution might change our way of restoring natural marine environments. What new tools are available that can improve the selection of environmental stress resistance and be implemented in conservation? What are the promises and perils of such approaches?

Share on FacebookTweet about this on TwitterEmail this to someone

Coral Bleaching Futures

Coral Bleaching Futures – Downscaled Projections of Bleaching Conditions for the World’s Coral Reefs, Implications of Climate Policy and Management Responses

Increasingly frequent severe coral bleaching is among the greatest threats to coral reefs posed by climate change. Global climate models (GCMs) project great spatial variation in the timing of annual severe bleaching (ASB) conditions; a point at which reefs are certain to change and recovery will be limited. Previous model-resolution projections (approximately 1×1°) are too coarse to inform reef management planning (recognized, for example, in SAMOA Pathways, paragraph 44b). To meet the need for higher-resolution projections, this report presents statistically downscaled projections (4-km resolution) of the timing of ASB for all the world’s coral reefs using the newest generation of IPCC climate models (CMIP5). Results are reported by country and territory, grouped in bioregions based on the 10 UNEP Regional Seas programmes with coral reefs (also including countries or territories in or near the Regional Sea area but not participating in the Regional Sea).

Among the goals of the Paris Agreement adopted at the UNFCCC Conference of Parties (COP) in 2015 is to hold temperature “well below” 2°C while also pursuing efforts to stay below 1.5°C. This legally binding agreement entered into force November 4, 2016. This report evaluates the implications of the Paris Agreement for coral reef futures. Projections of ASB timing are compared between business as usual scenario (RCP8.5) and RCP4.5, which could represent emissions concentrations mid-century. This report makes the projections data and main findings publicly accessible to inform management and policy planning as well as to support education and outreach. The data are currently being used to inform conservation planning in the U.S., including Florida and Hawaii, French Polynesia, Indonesia, Australia, and Malaysia.

Author: United Nations Environment Program
Year: 2017
View Full Article

Nairobi, Kenya. ISBN: 978-92-807-3649-6

Share on FacebookTweet about this on TwitterEmail this to someone

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.

Share on FacebookTweet about this on TwitterEmail this to someone

Population Genetic Structure Between Yap and Palau for the Coral Acropora Hyacinthus

(ALL INTERNAL, LIMITED EXTERNAL USAGE RIGHTS) Vibrant coral reef in Palau. While looking healthy, the white corals are the early signs of a struggling habitat as they begin to bleach from warm waters often attributed to climate change. Unfortunately there is not a reef in Palau that has not been affected in some way by coral bleaching. The coral reefs of Palau are part of a massive interconnected system that ties together Micronesia and the Western Pacific. To protect these reefs the Conservancy joined with other experts to develop Transforming Coral Reef Conservation. The Conservancy has worked with Palau’s community leaders and government agencies since 1992. In that time we have helped bridge the gap between traditional and modern approaches to conservation. The Conservancy helped establish the Palau Conservation Society, a local environmental organization dedicated to protecting Palau’s natural heritage. PHOTO CREDIT: © Ian Shive

Vibrant coral reef in Palau. Photo © Ian Shive

Listen to our interview with Dr. Annick Cros, coral reef scientist at the Hawaiian Institute of Marine Biology to hear about highlights from her recent publication on population genetic structure between Yap and Palau and how genetics can be used in coral reef management.

Click the play button below to listen to the interview.

 

Interview Transcript 

Reef Resilience (RR): Hello everyone, Reef Resilience is interviewing Dr. Annick Cros, coral reef scientist at the Hawaiian Institute of Marine Biology where she will share highlights from her recent publication on population genetic structure between Yap and Palau and how genetics can be used to tackle conservation issues.

Annick Cros (AC): Hi everyone! Thanks for having me here.

RR: Can you start with introducing what population genetics is?

AC: In very simple terms, it is the study of genetic variations in populations to understand their structure, boundaries and connectivity with other populations. When you study population genetics, you typically ask questions such as: “How much gene flow is there between these two populations?” As a manager, you surprisingly ask very similar questions! “How much spillover will I get from this MPA and where will larvae recruit?” Or “are these two groups of turtles related and should I manage them as one?”

RR: How can population genetics be used as a tool in management?

AC: So you are right in thinking that using population genetics to solve a conservation issue can be time consuming, expensive and requires resources and skills you may not have. However, in the case of connectivity of marine organisms, and the design of MPA networks, population genetics seems to be the best tool that we have at the moment. This is due to the fact most marine organisms reproduce via minute pelagic larvae that are very difficult to track. Since we often rely on oceanographic models to predict where larvae will go and settle we do not always get the right answer. Population genetics will not track larvae directly but will give information on where larvae have settled over time. The paper that we wrote actually is an example of how to use population genetics to answer one of these questions. 

We used Palau as our case study because in 1998 Palau suffered heavy bleaching mortality. Yet by 2004-2005, studies showed that the reef had almost recovered. Managers and scientists wanted to know how it had recovered so quickly and where the coral larvae came from. One hypothesis that we had was supported by an oceanographic model was that Palau recovered from a pulse recruitment event from Yap, a neighboring island approximately 500 km away. We wanted to test if this was true. Using the coral Acropora hyacinthus, we tested for a founder effect between Yap and Palau. The founder effect states that if larvae originating from Yap had traveled to Palau and recolonized the reef, the same genetic signatures should be found on Yap and Palau but with less genetic diversity in Palau. And that’s because only a small fraction of Yap’s genetic diversity would have traveled to Palau. We found that this was not the case and we rejected the hypothesis that Yap was the sole source of larvae for Palau’s recovery. Other signs indicated that it was more than likely that Palau recovered from its own surviving colonies.

RR: How do the results from your paper translate into management actions that can be implemented on the ground?

AC: Knowing that Palau had not recovered from Yap but from it’s own surviving colonies, this gave us the tools to tell managers that the best strategy to increase Palau’s reef resilience was to not to invest in Yap’s coral reefs but to instead invest in protecting their reefs at home. We are currently looking at further information to see how to protect these coral reefs at home based on population genetics. 

Author: Cros, A., R.J. Toonen, S.W. Davies, and S.A. Karl
Year: 2016
View Abstract
Email for the full article: resilience@tnc.org

PeerJ4e2330. doi:10.7717/peerj.2330

Share on FacebookTweet about this on TwitterEmail this to someone