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

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Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands

Managing exposure of corals to oxybenzone, a common ingredient found in sunscreen lotions, is critical for managing for coral reef resilience. A new study found that coral planulae exposed to oxybenzone became deformed and sessile, and had an increased rate of bleaching which increased with increasing concentrations, affecting coral recruitment and juvenile survival. Because oxybenzone is a photoxicant, high light levels at or near the surface of the water where planulae of broadcasting species spend 2-4 days before settling may place them at higher risk than was seen in this laboratory study. Water samples were also collected in the U.S. Virgin Islands and Hawaii to determine oxybenzone concentrations occurring around swimming beaches. In this study, cell death was seen in seven Indo-Pacific and Caribbean coral species at concentrations similar to the water samples taken. Caribbean species sensitivity to oxybenzone was similar to the model of coral tolerance to other stressors (Gates and Edmunds 1999)—boulder corals and other slow growing species have a higher level of tolerance to stressors. For management, the data from this study can help predict changes to coral reef community structure in places with significant oxybenzone exposure and can be integrated into reef resilience management plans.

Author: Downs, C. A., E. Kramarsky-Winter, R. Segal, J. Fauth, S. Knutson, O. Bronstein, F.R. Ciner, R. Jeger, Y. Lichtenfeld, C.M. Woodley, P. Pennington, K. Cadenas, A. Kushmaro, and Y. Loya
Year: 2015
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Archives of Environmental Contamination and Toxicology. doi: 10.1007/s00244-015-0227-7

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Minimizing the Short-Term Impacts of Marine Reserves on Fisheries While Meeting Long-Term Goals for Recovery

No-take marine reserves are often proposed as management tools to recover small-scale fisheries, which, if enforced, can improve mid to long-term harvests and profits. However, the short-term losses may prevent fishers from supporting and implementing no-take reserves, resulting in a loss of recovery of fisheries. Trade-offs between short-term loss in profits and long-term benefits to small-scale fisheries were quantified, using a multispecies model of coral reef fisheries for one case study. Impacts of reserves at different time scales depend on the social and management context, but the key to gaining support for marine reserves is to quantify the trade-offs at different time scales for stakeholders and policy makers. Policies for implementing marine reserves that are flexible can offer options with less short-term losses for fisheries that can be more appealing to fishermen, while still reaping the long-term recovery benefits.

Author: Brown, C.J., S. Abdullah, and P.J. Mumby
Year: 2014
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Conservation Letters 8(3): 180-189

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Herbivory And The Resilience Of Caribbean Coral Reefs: Knowledge Gaps And Implications For Management

This paper explores herbivory and how it affects the resilience of coral reefs in the Caribbean. The authors identify important knowledge gaps that limit our ability to predict when herbivores are most likely to support resilience. The authors explore:

  • What processes operate to prevent or facilitate coral persistence and recovery, and how are these influenced by herbivory?
  • What are the independent and combined effects of different species of herbivores in limiting algae and facilitating reef-building corals?
  • What factors limit herbivore populations and the process of herbivory on coral reefs?

The impacts of herbivores on coral reef resilience are likely to be highly context- dependent, thus it is necessary to understand the roles that particular types of herbivores play in limiting harmful algae and facilitating corals under a range of environmental conditions to improve sustainable management of coral reef ecosystems.

The paper provides specific information to guide how to manage herbivore populations to facilitate healthy, resilient coral reefs. The authors present the following management recommendations/guidance:

  • Local management efforts should focus on minimizing direct sources of coral mortality, such as sedimentation and pollution, as well as restoring ecological processes, such as herbivory, that are important for coral persistence and recovery
  • Maintaining healthy herbivore populations is likely to mitigate the negative impacts of ocean warming since abundant herbivores can control algae that inhibit coral recovery following coral decline
  • Better spatial management of fishing could minimize trade-offs between the need to maintain high levels of grazing while supporting sustainable fisheries
  • Implementation of marine protected areas or other spatial restrictions on herbivore fishing will only be effective if we can sustainably manage herbivore populations outside of protected areas. Different species of parrotfishes have different life-history traits and different impacts on benthic communities, thus should not be managed as a single species complex
  • Managers will need to ensure that reefs have the right mix of herbivores to carry out the full set of functions normally performed by the herbivore guild
  • It is critical to protect seagrasses and mangroves, which are important nursery habitats for several species of Caribbean herbivores
  • In cases where degradation has been severe and feedbacks are operating that could slow or prevent coral recovery, management actions targeted specifically at breaking feedbacks that maintain reefs in a degraded state are necessary

Author: Adam, T.C., D.E. Burkepile B.I. Ruttenberg, and M.J. Paddack
Year: 2015
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Marine Ecology Progress Series 520:1-20

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Time Preferences and the Management of Coral Reef Fisheries

To better understand resource use patterns in Curaçao and Bonaire in the southeast Caribbean, the authors conducted a socioeconomic study of the time preferences and marine management preferences of local SCUBA divers and fishers. Through interviews with 197 divers and 153 fishers on the two islands, they calculated individual discount factors and present bias to evaluate time preferences and preferred strategies for managing coral reefs. Divers’ discount factors were significantly higher than fishers’, meaning they value the future more highly or are more future-biased. Divers, on average, supported more restrictions than fishers such as gear restrictions and marine reserves. And, only 1% of fishers were willing to limit the number of fishers, while 34% of divers were willing to limit the number of divers. Overall, divers were more supportive of management than fishers. The main management and policy implication of this study is that differences in diver and fisher groups should be addressed for effective marine management. The authors suggest offsets, such as a dive fee, like the Nature Fee in Bonaire used for marine park management. A portion of the fee could be used to pay fishers to reduce high-impact gears or the buyout of traps and nets. They also suggest property rights schemes within a larger management framework that includes some mix of gear or effort restrictions, incentives for sustainable use, enforcement, and local buy-in.

Author: Johnson, A.E. and D.K. Saunders
Year: 2014
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Ecological Economics 100: 130–139. doi: 10.1016/j.ecolecon.2014.01.004

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Belize – Fisheries Management

Protecting Reef Grazers to Enable Coral Reef Recovery: An Innovative Coral Reef Management Approach in Belize

Belize Barrier Reef System, Belize

The Challenge
Belize is well known for its incredible biodiversity, both terrestrial and marine. Its reefs have long been considered some of the Caribbean’s most pristine and unique reefs, however they started to show worrying signs of damage at the turn of this century. A 2006 survey of 140 reefs throughout Belize found that live coral cover had declined from approximately 30% in 1995 to an average of 11%. The Wildlife Conservation Society (WCS), which has been working in Belize since the 1980s to help conserve the country’s marine environment, carries out research on the health of Belize’s fisheries from their Marine Reserve Station at Glover’s Reef.

Location of the Belize Barrier Reef System

Location of the Belize Barrier Reef System.

Glover’s Reef is located within the Belize Barrier Reef Reserve System, where fishing, as well as spearfishing, is allowed. WCS found that groupers and some snappers are now overfished and that the proportion of parrotfish in the catch doubled between 2004 and 2008 because parrotfish are considered by fishermen as “the next best fish” to harvest.

The fact that fishermen were targeting reef-grazing species was a serious problem with far-reaching effects for the health of Belize’s reefs. Reef-grazers such as parrotfish play a critical ecological role within coral reefs; by eating large amounts of algae, they keep its growth in check, making sure that it does not overgrow the reef. Algae can smother corals, stunt their growth, and reduce their recruitment success.

Rainbow parrotfish (Scarus guacamaia), the largest herbivorous fish in the Caribbean. Photo © Julio Maaz (WCS).

Rainbow parrotfish (Scarus guacamaia), the largest herbivorous fish in the Caribbean. © Julio Maaz/WCS

The health of reefs is therefore closely linked to the presence of herbivorous fish such as parrotfish. As fishermen in Belize continued to harvest parrotfish, their numbers started to rapidly go down. Research on the change in fish communities after a seven-year period (2002-2009) of fishing in Belize showed a 41% decline in parrotfish over that time period. Overfishing parrotfish already has had observable effects on Belize’s reefs. One study found that an atoll reef lagoon at Glover’s Reef that had once been very healthy with a 75% coral cover now has less than 20% coral cover because of algae over-growth.

Actions Taken
The traditional management option to help overfished species recover has typically been fishing closures. However, WCS conducted a 14-year study at Glover’s Reef and found that while a fishing ban in the Conservation Zone of the marine reserve was effective in helping predatory species such as barracudas and snappers recover, it had little effect on the recovery of herbivorous species. This meant that a fishing ban would not be enough to reduce the growth of algae and help corals recover. This information, along with recent information on the poor health of Belize’s reefs, helped stakeholders understand the need for an alternative and more innovative way to protect Belize’s reefs: protect major reef grazers. It was local fishermen who first voluntarily recommended a ban on fishing parrotfish after it was made clear to them how important these fish were to the health of the reef and therefore to their livelihoods. In April 2009, the voluntary ban on the fishing of parrotfish became national law when the government of Belize passed a new set of regulations (Fisheries Regulations 2009) to protect overfished species.

A typical fishing boat used in Belize © Julio Maaz (WCS).

A typical fishing boat used in Belize. © Julio Maaz/WCS

The first of the new regulations prohibits any taking of parrotfish and surgeonfish in Belize’s waters. Both species are major reef-grazers, so this law directly addresses the recent increase in catch of herbivorous fish and the negative impact this is having on reef health. By giving parrotfish and surgeonfish full protection, the hope is to help their numbers recover and to in turn reduce the growth of algae that is threatening Belize’s reefs. Belize is the first country to pass a national law to protect reef grazers, which are critical to the health of coral reefs. In fact, many consider this new law a new standard for coral reef protection, as management strategies have until now focused on marine protected areas (MPAs). Of course, enforcement and compliance is key to ensuring the success of this national-level ban. WCS is providing technical aid to the Belize Fisheries Department to ensure that fisheries officers and patrols enforce this new law.

Dr. Peter Mumby explains the importance of parrotfish as grazers maintaining the health of coral reefs to a large group of fishermen in Belize City © WCS.

Dr. Peter Mumby explains the importance of parrotfish as grazers maintaining the health of coral reefs to a large group of fishermen in Belize City. © WCS

A second set of the new regulations helps protect the endangered Nassau Grouper (Epinephelus striatus), which is currently listed as Endangered by the IUCN Red List of Threatened Species. Fishing of the Nassau Grouper is still allowed but is now heavily regulated – there is now a minimum and maximum size limit, and all groupers must be brought in whole so that catch rates can be monitored. Additionally, spawning aggregations of Nassau grouper are protected, and spearfishing is now banned within marine reserves. A third set of regulations creates a number of “no-take” zones in protected areas, which are closed to fishing. The areas selected are biodiversity hotspots with unique and/or fragile ecosystems and/or species.

How successful has it been?
It is difficult at this time to evaluate the effect that the national-level ban on major reef-grazers has had on Belize’s coral reef health due to the fact that the law was passed just a few years ago in 2009. WCS is conducting ongoing monitoring at Glover’s Reef to evaluate the recovery of parrotfish at this site, but there are no clear indications of increases in density yet. There is however some strong evidence that the fishing ban is helping reef-grazers recover. In 2011, the herbivore biomass in Belize surpassed levels recorded in 2006 and increased 33% above the low levels measured in 2009. This increase in herbivore biomass should in time signify a decrease in algae dominance in Belize’s reefs.

Stoplight parrotfish (Sparisoma viride) with blue tangs, which are also protected grazers © Virginia Burns (WCS).

Stoplight parrotfish (Sparisoma viride) with blue tangs, which are also protected grazers. © Virginia Burns/WCS

The effectiveness of the fishing ban in restoring fish populations and coral assemblages in Belize was evaluated in a study between 2009 and 2011. Increases in herbivorous fish biomass were found at approximately half of the studied sites, but coral and macroalgal cover stayed the same. However, the authors of the study attribute the lack of change in coral and algae cover to how recent the ban on fishing reef-grazers was.

Enforcement efforts appear to be successful as there have been very few instances of illegal catch of parrotfish since the ban was introduced. The results of a 2012 genetic study of fillet samples throughout Belize also demonstrate very good compliance with the ban – over 90% of the fillets checked were not parrotfish.

Lessons Learned and Recommendations
Lessons learned and some key recommendations include:

  • Extensive research on the subject at hand (in this case, the link between parrotfish density and reef health) is essential to making informed decisions.
  • Extensive research is also vital in explaining and gaining the trust of local stakeholders. If they see that research clearly supports a certain point, they are more likely to comply with it.
  • Fishermen are key stakeholders in marine conservation because so much of what they do in their daily lives impacts the ocean. It is vital to gain their support and to clearly explain to them how important healthy reefs are to their livelihoods.
  • Engaging fishers from the area can provide a wealth of local knowledge, as well as buy-in and compliance later on.
  • Reef recovery takes time – although three years of data indicates an increase in biomass of parrotfishes, slow-growing corals will need long-term protection to fully recover.
  • MPAs and community-level conservation efforts are an important part of coral reef conservation but certain issues require solutions with a broader approach.

Funding Summary
The monitoring and fisheries catch data collection programs of WCS have been carried out for many years in partnership with the Fisheries Department, and they will continue in an effort to record the recovery of parrotfish at Glover’s Reef and track the health of the coral reef. This work was funded primarily by the Oak Foundation, USAID, and the Summit Foundation.

Lead Organizations
Wildlife Conservation Society
Belize Fisheries Department

Belize Takes Action to Save Coral Reefs & Fisheries, Wildlife Conservation Society (pdf)

Belize Limits Reef Fishing, Wildlife Conservation Society

Belize protected area boosting predatory fish populations, Wildlife Conservation Society

Fishing down a Caribbean food web relaxes trophic cascades (pdf)

Testing for top-down control: can post-disturbance fisheries closures reverse algal dominance (pdf)

Written by: Florence Depondt

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