Where Can Science Make a Difference to People?

Hundreds of millions of people worldwide depend on coral reef ecosystems[1].

Coral reef ecosystems create natural barriers that protect shorelines from storm surge and erosion—defending villages, businesses, and coastal residents[2].

Coral reef ecosystems also support fisheries that provide food [3], jobs, and income for local communities [4,5] as well as tourism and recreation that contribute to jobs, profits, taxes, and foreign income[3].

The recreational and cultural services provided by these ecosystems also benefit local communities and people.

Increasing levels of carbon dioxide in the atmosphere put shallow, warm-water coral reef ecosystems, and the people who depend upon them at risk from two key global environmental stresses:

1) elevated sea surface temperature (that can cause coral bleaching and related mortality), and

2) ocean acidification (OA). Bleaching and OA can compound local reef stresses that will hasten the loss of the ecosystem services provided by reefs (Fig 1).

Structural damage to coral reefs can result in more severe coastal inundation that puts lives and property at risk [6]. These environmental stresses will also decrease coral ecosystem health and productivity [7,8], which in turn could jeopardize nutrition, livelihoods, and local incomes that depend on reef fisheries and could impact reef-related tourism[5].

We acknowledge that coral reef ecosystems are also threatened by other local stressors that include overfishing, destructive fishing, disease, predators, pollution, eutrophication, sedimentation, and episodic de-oxygenation [9]. Nevertheless, we focus on elevated sea surface temperature and OA because these factors are largely beyond the control of coastal communities, managers of marine protected areas, and other management bodies that exist at the country level or smaller [10].

Coral reef countries have four primary options to counter the threats to reefs caused by the emission of CO2 [11]:

1) urge governments of major CO2-emitting nations (many of which are also home to coral reefs) to reduce carbon emissions that cause both climate change and OA,

2) reduce damages to corals caused by local environmental stressors that can make these problems worse, and

3) improve and/or restore associated ecosystems (e.g. mangroves) to a state that could replace lost ecosystem services and thus minimize impacts on people.

Engineering responses, other than green infrastructure and restoration, to counter these global threats have also been proposed [12,13], but they are largely untested. Without these measures, countries dependent on coral reef ecosystems may need to cope with a world with greatly diminished coral reefs–a response that could spur human migration.

Fig 6. Regional dependence, by ocean province [49], on ecosystem services and average CO2-related threats (ocean acidification measured as projected ?ar levels at coral reefs in 2050 and elevated sea surface temperature as measured by year that 8 DHW are projected to occur annually). The horizontal line in the threats panel represents the mean threat for all regions (scores above this line indicate above average severity of threat). The scales for the reef fish dependence scores are broken to reduce the size of the graph. Note that the Great Barrier Reef Ocean Province includes, but is not limited to, the Great Barrier Reef.
Fig 6. Regional dependence, by ocean province [49], on ecosystem services and average CO2-related threats (ocean acidification measured as projected ?ar levels at coral reefs in 2050 and elevated sea surface temperature as measured by year that 8 DHW are projected to occur annually).
The horizontal line in the threats panel represents the mean threat for all regions (scores above this line indicate above average severity of threat). The scales for the reef fish dependence scores are broken to reduce the size of the graph. Note that the Great Barrier Reef Ocean Province includes, but is not limited to, the Great Barrier Reef.

Reefs and People at Risk

Increasing levels of carbon dioxide in the atmosphere put shallow, warm-water coral reef ecosystems, and the people who depend upon them at risk from two key global environmental stresses:

1) elevated sea surface temperature (that can cause coral bleaching and related mortality), and

2) ocean acidification.

These global stressors: cannot be avoided by local management, compound local stressors, and hasten the loss of ecosystem services.

Impacts to people will be most grave where

a) human dependence on coral reef ecosystems is high,

b) sea surface temperature reaches critical levels soonest, and

c) ocean acidification levels are most severe.

Where these elements align, swift action will be needed to protect people’s lives and livelihoods, but such action must be informed by data and science.

Fig 1. A conceptual diagram linking stresses related to increased atmospheric CO2 (elevated sea surface temperature and ocean acidification), storms, and local stressors to coral reef condition, selected ecosystem services provided by reefs, and human dependence on these ecosystem services. Solid lines represent relationships evaluated in this study. http://dx.doi.org/10.1371/journal.pone.0164699.g001
Fig 1. A conceptual diagram linking stresses related to increased atmospheric CO2 (elevated sea surface temperature and ocean acidification), storms, and local stressors to coral reef condition, selected ecosystem services provided by reefs, and human dependence on these ecosystem services.
Solid lines represent relationships evaluated in this study. http://dx.doi.org/10.1371/journal.pone.0164699.g001

An Indicator Approach

Designing policies to offset potential harm to coral reef ecosystems and people requires a better understanding of where CO2-related global environmental stresses could cause the most severe impacts.

Mapping indicators has been proposed as a way of combining natural and social science data to identify policy actions even when the needed science is relatively nascent.

To identify where people are at risk and where more science is needed, we map indicators of biological, physical and social science factors to understand how human dependence on coral reef ecosystems will be affected by globally-driven threats to corals expected in a high-CO2 world. Western Mexico, Micronesia, Indonesia and parts of Australia have high human dependence and will likely face severe combined threats.

As a region, Southeast Asia is particularly at risk. Many of the countries most dependent upon coral reef ecosystems are places for which we have the least robust data on ocean acidification.

These areas require new data and interdisciplinary scientific research to help coral reef-dependent human communities better prepare for a high CO2 world.

Fig 3. Country-level dependence on coral reef ecosystem services and future risk of coral bleaching. Bleaching risk is indicated by the year when DHW8 is first reached annually, under RCP8.5 scenario [24,25]. Ocean Provinces are indicated in each panel in bold. Earlier years indicate increased bleaching risk
Fig 3. Country-level dependence on coral reef ecosystem services and future risk of coral bleaching.
Bleaching risk is indicated by the year when DHW8 is first reached annually, under RCP8.5 scenario [24,25]. Ocean Provinces are indicated in each panel in bold. Earlier years indicate increased bleaching risk

Maps Website

Cool website with all this graphically:

https://grid-arendal.maps.arcgis.com/apps/Cascade/index.html?appid=2f440e93fefa4cce8e660c259bd23b50

This map shows the number of people protected by reefs in different regions.
This map shows the number of people protected by reefs in different regions.

Citation

Pendleton L, Comte A, Langdon C, Ekstrom JA, Cooley SR, Suatoni L, et al. (2016) Coral Reefs and People in a High-CO2 World: Where Can Science Make a Difference to People? PLoS ONE 11(11): e0164699. doi:10.1371/journal.pone.0164699

Editor: Stefano Goffredo, University of Bologna, ITALY

Pendleton L, Comte A, Langdon C, Ekstrom JA, Cooley SR, et al. (2016)

Coral Reefs and People in a High-CO2 World: Where Can Science Make a Difference to People?

PLOS ONE 11(11): e0164699. doi: 10.1371/journal.pone.0164699

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0164699

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