Can We Help Corals Evolve to Survive Global Warming?

With ocean temperatures rising and coral bleaching events becoming more and more common, attempts to reduce or reverse climate change may seem to be too little too late, and we are left wondering if there is anything that can be done to save the coral reefs.

One form of helping repair damaged reefs is to grow corals in nurseries and transplant them to the reef.  This technique has been successful and useful for replanting damaged reefs.1 In coral nurseries, researchers, and therefore the corals, have access to greater, more controlled resources, which also allows greater protection from predation.   Abiotic factors are those nonliving, physical and chemical attributes that can influence an environment or ecosystem. In some cases, abiotic factors that could be harmful can also be restricted in coral nurseries, such that temperatures, pH, light, and other factors are strictly controlled. However, if these corals are not suited to the natural environment in which they will eventually be placed, where temperature stress cannot be controlled, they still most likely will die.1

Assisted evolution, is the process whereby researchers help speed along natural selection through different methods to enable corals to be better equipped with traits that will allow them to survive predicted changes in ocean conditions. Dr. Madeline van Oppen and colleagues argue that assisted evolution may be extremely important in helping corals survive, despite rising ocean temperatures. They propose that there are four main ways that assisted evolution could be used in coral reefs, shown in figure 1.  These researchers further state that all methods need more research to be developed well enough to be implemented.1

Fig. 1: The assisted evolution diagram shows the four proposed approaches to assisted evolution in order of increasing intensity of intervention and the actions that would be taken with each and how these methods would be applicable. Source: van Oppen et. al. 2015.

The first approach involves exposing corals to stressful conditions so that they will be better able to acclimate in the future.1It has been shown that exposing some corals to moderate light and temperature stress enables them to better resist bleaching during future stressful events.1 Exposure to stressful conditions may change corals’ sensitivity to heat stress through epigenetics, changing which gene is expressed and to what extent. Essentially, the corals are increasing their tolerance to conditions of unusual light and temperatures.

The second method of increasing coral resilience is through modifying the microbial community associated with coral.1 All corals live with other creatures in their ecosystems.  When the creatures coexist in a mutually advantageous way, they are said to be symbiotic. Exposure to stress allows the corals to change the relative abundance of different types of symbiotic algae contained in their tissues in favor of a higher abundance of those symbionts more suited for future conditions.1   Symbiodinium are algae composed of one cell, that tend to live in harmony with corals.  Their photosynthetic biproducts are used by the corals.   Dr. Robert Rowan has shown that a group of Symbiodinium, called clade D, function better in higher temperature water than another group, clade C.3 When exposed to stressful temperature conditions, clade D exhibited better functioning of chlorophyll than clade C. These results indicate that high temperature causes photoinhibition of clade C, while it causes photoprotection in clade D.3 By introducing heat tolerant Symbiodinium to corals, the heat tolerance of the corals may actually increase.1

A third way that assisted evolution could benefit corals is by selective breeding.  The authors suggest selective breeding only those individuals with higher heat tolerance and thereby speed along the process of natural selection.1 This approach has not been researched in corals; however, it could be done through selective breeding or hybridization of species.1 A naturally occurring Acropora hybrid, a coral found in the Caribbean, has occasionally shown increased fitness compared to the parent species.1 Because corals bred through either of these procedures would have unknown effects on the environment, these individuals would need to be raised in a lab to minimize threats to the naturally occurring ecosystem and to identify genotypes that are most suited to predicted future conditions.1 In addition, it is unknown if many phenotypic traits observed in corals are due to heritable genetic factors or environmental factors. Selective breeding would only work with heritable factors.1 What limited research exists only shows limited heritability for heat tolerance in coral.1 Corals that already exist on naturally warmer reefs could also be moved to naturally cooler reefs that are experiencing high temperatures and losing coral cover.1

Finally, it might be possible to artificially evolve and select for Symbiodinium that show greater heat tolerance.1 This might be done by inducing a high mutation rate in lab-grown Symbiodinium and raising them in stressful environments mimicking predicted future environments to select for those strains with the highest fitness.1 The well-suited strains could then be introduced to corals. This method is only theoretical at this point and has not been tried in corals.

This research no doubt has some ethical questions attached to it. Should we really be “playing God” and choosing what traits these organisms have?  Or should we just allow nature to take its course, even though we humans are causing the rise in greenhouse gases, which subsequently leads to increased air and ocean temperatures?2 But there are also some very real ecological questions to be answered regarding assisted evolution. For instance, what effects would organisms that were bred in the lab have on native organisms, and could these organisms potentially harm other native species?1 Van Oppen and her colleagues admit that, while she does not propose drastic changes such as genetic engineering, but rather techniques more along the lines of artificial selection, there could be negative outcomes.1 They also believe that what types of intervention are involved, the potential risks to the ecosystem involved, the health of the coral, and projected future reef health all must be analyzed and considered before taking action to increase coral resilience.

Even though these techniques seem to be promising ways that scientists can prepare corals for future conditions, it is still imperative that the issue of climate change be addressed. It is our job to do what we can to reduce our own contributions to climate change.

References:

  1. van Oppen, M.J.H., Oliver, J.K., Putnam, H.M., and Gates, R.D. (2015). Building coral reef resilience through assisted evolution. Proceedings of the National Academy of Sciences 112, 2307–2313.
  2. van Oppen, M.J.H., Gates, R.D., Blackall, L.L., Cantin, N., Chakravarti, L.J., Chan, W.Y., Cormick, C., Crean, A., Damjanovic, K., Epstein, H., et al. (2017). Shifting paradigms in restoration of the world’s coral reefs. Global Change Biology.
  3. Rowan, R. (2004). Coral bleaching: Thermal adaptation in reef coral symbionts. Nature 430, 742–742.

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Can We Help Corals Evolve to Survive Global Warming?

With ocean temperatures rising and coral bleaching events becoming more and more common, attempts to reduce or reverse climate change may seem to be too little too late, and we are left wondering if there is anything that can be done to save the coral reefs.

One form of helping repair damaged reefs is to grow corals in nurseries and transplant them to the reef.  This technique has been successful and useful for replanting damaged reefs.1 In coral nurseries, researchers, and therefore the corals, have access to greater, more controlled resources, which also allows greater protection from predation.   Abiotic factors are those nonliving, physical and chemical attributes that can influence an environment or ecosystem. In some cases, abiotic factors that could be harmful can also be restricted in coral nurseries, such that temperatures, pH, light, and other factors are strictly controlled. However, if these corals are not suited to the natural environment in which they will eventually be placed, where temperature stress cannot be controlled, they still most likely will die.1

Assisted evolution, is the process whereby researchers help speed along natural selection through different methods to enable corals to be better equipped with traits that will allow them to survive predicted changes in ocean conditions. Dr. Madeline van Oppen and colleagues argue that assisted evolution may be extremely important in helping corals survive, despite rising ocean temperatures. They propose that there are four main ways that assisted evolution could be used in coral reefs, shown in figure 1.  These researchers further state that all methods need more research to be developed well enough to be implemented.1

Fig. 1: The assisted evolution diagram shows the four proposed approaches to assisted evolution in order of increasing intensity of intervention and the actions that would be taken with each and how these methods would be applicable. Source: van Oppen et. al. 2015.

The first approach involves exposing corals to stressful conditions so that they will be better able to acclimate in the future.1It has been shown that exposing some corals to moderate light and temperature stress enables them to better resist bleaching during future stressful events.1 Exposure to stressful conditions may change corals’ sensitivity to heat stress through epigenetics, changing which gene is expressed and to what extent. Essentially, the corals are increasing their tolerance to conditions of unusual light and temperatures.

The second method of increasing coral resilience is through modifying the microbial community associated with coral.1 All corals live with other creatures in their ecosystems.  When the creatures coexist in a mutually advantageous way, they are said to be symbiotic. Exposure to stress allows the corals to change the relative abundance of different types of symbiotic algae contained in their tissues in favor of a higher abundance of those symbionts more suited for future conditions.1   Symbiodinium are algae composed of one cell, that tend to live in harmony with corals.  Their photosynthetic biproducts are used by the corals.   Dr. Robert Rowan has shown that a group of Symbiodinium, called clade D, function better in higher temperature water than another group, clade C.3 When exposed to stressful temperature conditions, clade D exhibited better functioning of chlorophyll than clade C. These results indicate that high temperature causes photoinhibition of clade C, while it causes photoprotection in clade D.3 By introducing heat tolerant Symbiodinium to corals, the heat tolerance of the corals may actually increase.1

A third way that assisted evolution could benefit corals is by selective breeding.  The authors suggest selective breeding only those individuals with higher heat tolerance and thereby speed along the process of natural selection.1 This approach has not been researched in corals; however, it could be done through selective breeding or hybridization of species.1 A naturally occurring Acropora hybrid, a coral found in the Caribbean, has occasionally shown increased fitness compared to the parent species.1 Because corals bred through either of these procedures would have unknown effects on the environment, these individuals would need to be raised in a lab to minimize threats to the naturally occurring ecosystem and to identify genotypes that are most suited to predicted future conditions.1 In addition, it is unknown if many phenotypic traits observed in corals are due to heritable genetic factors or environmental factors. Selective breeding would only work with heritable factors.1 What limited research exists only shows limited heritability for heat tolerance in coral.1 Corals that already exist on naturally warmer reefs could also be moved to naturally cooler reefs that are experiencing high temperatures and losing coral cover.1

Finally, it might be possible to artificially evolve and select for Symbiodinium that show greater heat tolerance.1 This might be done by inducing a high mutation rate in lab-grown Symbiodinium and raising them in stressful environments mimicking predicted future environments to select for those strains with the highest fitness.1 The well-suited strains could then be introduced to corals. This method is only theoretical at this point and has not been tried in corals.

This research no doubt has some ethical questions attached to it. Should we really be “playing God” and choosing what traits these organisms have?  Or should we just allow nature to take its course, even though we humans are causing the rise in greenhouse gases, which subsequently leads to increased air and ocean temperatures?2 But there are also some very real ecological questions to be answered regarding assisted evolution. For instance, what effects would organisms that were bred in the lab have on native organisms, and could these organisms potentially harm other native species?1 Van Oppen and her colleagues admit that, while she does not propose drastic changes such as genetic engineering, but rather techniques more along the lines of artificial selection, there could be negative outcomes.1 They also believe that what types of intervention are involved, the potential risks to the ecosystem involved, the health of the coral, and projected future reef health all must be analyzed and considered before taking action to increase coral resilience.

Even though these techniques seem to be promising ways that scientists can prepare corals for future conditions, it is still imperative that the issue of climate change be addressed. It is our job to do what we can to reduce our own contributions to climate change.

References:

  1. van Oppen, M.J.H., Oliver, J.K., Putnam, H.M., and Gates, R.D. (2015). Building coral reef resilience through assisted evolution. Proceedings of the National Academy of Sciences 112, 2307–2313.
  2. van Oppen, M.J.H., Gates, R.D., Blackall, L.L., Cantin, N., Chakravarti, L.J., Chan, W.Y., Cormick, C., Crean, A., Damjanovic, K., Epstein, H., et al. (2017). Shifting paradigms in restoration of the world’s coral reefs. Global Change Biology.
  3. Rowan, R. (2004). Coral bleaching: Thermal adaptation in reef coral symbionts. Nature 430, 742–742.

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What Next for Deep Water Corals?

So deep water coral reefs are a thing, and they’re being threatened by human action, but what comes next? We are far from knowing everything about these hidden forests of biodiversity and even farther from adequately protecting them from the damage we’re inflicting on them. In the coming decades it is of utmost importance to expand our knowledge of deep water reefs and enact new legislation to protect them.

Due to the recent discovery of these reefs and the inherent difficulty in studying ecosystems 4000m (13000ft) under the sea, there is much we don’t know about these communities.  From large scale issues like where in the oceans are these deep water systems and what physical factors affect where they can grow to smaller scale questions like analyzing how they interact with plants and animals in the area and what kind of relationships they have with microbes that are present in the reef, there is a lot of knowledge left to discover on these reefs. And although this may sound like a lot, all of these goals are achievable with existing technologies. Using mapping techniques like multibeam sonar devices to create topographic maps of the ocean floor, we can create low resolution maps in areas that are likely to have reefs and determine we should be looking for these elusive habitats. From there these reefs can be examined and sampled by deep water submersibles that are able to travel to the depths of these reefs. Samplings of coral can help us better understand the amount of diversity present in these reefs and possibly give insight into microbes present.1,2,3

A deep water submersible used to study habitats up to 3000m deep.
© Harbor Branch Oceanographic Institute

On a more legislative side, more needs to be done to protect these reefs. Currently Australia, Canada, the Canary Islands, Ireland, New Zealand, Norway, UK and the United States all have created marine reserves or halted destructive activity like trawling and commercial drilling in areas with deep water reefs, but it’s not quite enough. Although many of known areas are protected areas, many are not or are still in the reviewing process. In addition, we are lacking full scientific data on where reefs are located. Hopefully this can be solved with new mapping techniques being used to find these reefs.1,4

1Svensen, E. Coral reefs: Cold water corals. WWF. http://ift.tt/2nWsYCg
2Watling, L. Auster, P. J. (2017) Seamounts on the High Seas Should be Managed as Vulnerable Marine Ecosystems. Frontiers in Marine Science. 4:14
3Ocean Portal. Deep Sea Corals. Smithsonian Museum of Natural History http://ift.tt/1dWJvP0
4Roberts JM (2006) Reefs of the Deep: The Biology and Geology of Cold-Water Coral Ecosystems. Science 312:543–547.

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What Next for Deep Water Corals?

So deep water coral reefs are a thing, and they’re being threatened by human action, but what comes next? We are far from knowing everything about these hidden forests of biodiversity and even farther from adequately protecting them from the damage we’re inflicting on them. In the coming decades it is of utmost importance to expand our knowledge of deep water reefs and enact new legislation to protect them.

Due to the recent discovery of these reefs and the inherent difficulty in studying ecosystems 4000m (13000ft) under the sea, there is much we don’t know about these communities.  From large scale issues like where in the oceans are these deep water systems and what physical factors affect where they can grow to smaller scale questions like analyzing how they interact with plants and animals in the area and what kind of relationships they have with microbes that are present in the reef, there is a lot of knowledge left to discover on these reefs. And although this may sound like a lot, all of these goals are achievable with existing technologies. Using mapping techniques like multibeam sonar devices to create topographic maps of the ocean floor, we can create low resolution maps in areas that are likely to have reefs and determine we should be looking for these elusive habitats. From there these reefs can be examined and sampled by deep water submersibles that are able to travel to the depths of these reefs. Samplings of coral can help us better understand the amount of diversity present in these reefs and possibly give insight into microbes present.1,2,3

A deep water submersible used to study habitats up to 3000m deep.
© Harbor Branch Oceanographic Institute

On a more legislative side, more needs to be done to protect these reefs. Currently Australia, Canada, the Canary Islands, Ireland, New Zealand, Norway, UK and the United States all have created marine reserves or halted destructive activity like trawling and commercial drilling in areas with deep water reefs, but it’s not quite enough. Although many of known areas are protected areas, many are not or are still in the reviewing process. In addition, we are lacking full scientific data on where reefs are located. Hopefully this can be solved with new mapping techniques being used to find these reefs.1,4

1Svensen, E. Coral reefs: Cold water corals. WWF. http://ift.tt/2nWsYCg
2Watling, L. Auster, P. J. (2017) Seamounts on the High Seas Should be Managed as Vulnerable Marine Ecosystems. Frontiers in Marine Science. 4:14
3Ocean Portal. Deep Sea Corals. Smithsonian Museum of Natural History http://ift.tt/1dWJvP0
4Roberts JM (2006) Reefs of the Deep: The Biology and Geology of Cold-Water Coral Ecosystems. Science 312:543–547.

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ENSOs of The Future: The Necessity of Diligence

In the years to come, understanding the effects of El Niño-Southern Oscillation events on coral reefs is instrumental to preserving the beauty and function of these valuable oceanic resources. El Niños, as far as experts can tell, have been occurring for thousands of years, and so they alone are not the concern; the worry is how their growing strength (in connection with global warming) will affect overall climate trends and the natural world. Numerous studies have demonstrated how the 2015-16 El Niño was extraordinarily impactful in this regard, and so these are great tools for putting a finger on just how potent a strong ENSO can be on coral reef ecosystems.

The obvious connection between the increasing global effects of climate change, and bleaching of coral reefs, is the associated elevation of sea surface temperature1. As the Earth’s oceans continue to be heated as a result of human-induced pollution and warming, the severity of temperature increases such as those resulting from El Niño become more and more devastating to reefs. However, this is not the only factor that could potentially affect the survival of coral during future El Niños.

Figure 1: A reef off the coast of Bali, Indonesia Image Credit: Coral Staff, Coral Reef Alliance http://ift.tt/2pIp6pc

A 2016 study published by experts from the European Geosciences Union highlights a different potential cause of coral mortality during the 2015-16 El Niño: sea level fall2. It focused on the reefs of Indonesia (Figure 1), a region known for its high diversity and flourishing tracts, where coral bleaching is common during ENSO cycles; this is a result of the added warmth and dryness during its first phase3. They not only saw that traditional warming-related threats arose, but also that additionally, sea level had lowered considerably in the area (Figure 2)2.

Figure 1: Sea level variance from Overall Mean on coral near Bunaken Island, Indonesia (1993-2016)
Image Credit – Eghbert et al. 2016 (See Ref. 2)

They collected data from years in the past, and noticed that in previous years with strong ENSOs, (such as 1997), sea level had also fallen noticeably. The establishment of an association between these two negative effects on coral reefs allowed them to conclude that sea level fall was likely not seen as a notable detriment of past El Niños2, and that this new factor is a major concern moving forward with the study of reefs during ENSO cycles.

As is made evident in this case study, it’s easy (even for scientists) to overlook the wide range of impacts that ENSOs can have on coral reef health. Sea surface temperature anomaly is the most obvious, and pressing issue involving global warming and the survival of these majestic underwater ecosystems, but others do exist, and should not be ignored. As climate change worsens, El Niños continue to become stronger, and so do their effects on the living world. Some, as we have learned, may still not even be discovered.

Therefore, it is crucial to remain diligent when attempting to quantify and study the adverse challenges presented by global warming. Coral reefs can only be saved through mass cultural understanding, both by experts, and members of the community (like YOU!). If we are to combat the growing strength of ENSOs in the coming decades, it starts with the small things, including comprehending the gravity situation we are confronted with.

References:

1- “El Niño prolongs longest global coral bleaching event.” News and Features – NOAA, pub. online 23 Feb. 2016. Web. 20 Feb 2017. http://ift.tt/2lkdLLM

2- Eghbert, Elvan A., et al. “Coral Mortality Induced by the 2015-2016 El-Niño in Indonesia: The Effect of Rapid Sea Level Fall.” Biogeosciences, vol. 14, no. 4, 2017, pp. 817-826. SciTech Premium Collection. http://ift.tt/2pIvJYK, doi:http://ift.tt/2lyjNIR

3 – Lindsey, Rebecca. “Global impacts of El Niño and La Niña.” Climate.gov – NOAA, pub. online 9 Feb. 2016. Web. 20 Feb. 2017. http://ift.tt/1Tb8jVF

 

 

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ENSOs of The Future: The Necessity of Diligence

In the years to come, understanding the effects of El Niño-Southern Oscillation events on coral reefs is instrumental to preserving the beauty and function of these valuable oceanic resources. El Niños, as far as experts can tell, have been occurring for thousands of years, and so they alone are not the concern; the worry is how their growing strength (in connection with global warming) will affect overall climate trends and the natural world. Numerous studies have demonstrated how the 2015-16 El Niño was extraordinarily impactful in this regard, and so these are great tools for putting a finger on just how potent a strong ENSO can be on coral reef ecosystems.

The obvious connection between the increasing global effects of climate change, and bleaching of coral reefs, is the associated elevation of sea surface temperature1. As the Earth’s oceans continue to be heated as a result of human-induced pollution and warming, the severity of temperature increases such as those resulting from El Niño become more and more devastating to reefs. However, this is not the only factor that could potentially affect the survival of coral during future El Niños.

Figure 1: A reef off the coast of Bali, Indonesia Image Credit: Coral Staff, Coral Reef Alliance http://ift.tt/2pIp6pc

A 2016 study published by experts from the European Geosciences Union highlights a different potential cause of coral mortality during the 2015-16 El Niño: sea level fall2. It focused on the reefs of Indonesia (Figure 1), a region known for its high diversity and flourishing tracts, where coral bleaching is common during ENSO cycles; this is a result of the added warmth and dryness during its first phase3. They not only saw that traditional warming-related threats arose, but also that additionally, sea level had lowered considerably in the area (Figure 2)2.

Figure 1: Sea level variance from Overall Mean on coral near Bunaken Island, Indonesia (1993-2016)
Image Credit – Eghbert et al. 2016 (See Ref. 2)

They collected data from years in the past, and noticed that in previous years with strong ENSOs, (such as 1997), sea level had also fallen noticeably. The establishment of an association between these two negative effects on coral reefs allowed them to conclude that sea level fall was likely not seen as a notable detriment of past El Niños2, and that this new factor is a major concern moving forward with the study of reefs during ENSO cycles.

As is made evident in this case study, it’s easy (even for scientists) to overlook the wide range of impacts that ENSOs can have on coral reef health. Sea surface temperature anomaly is the most obvious, and pressing issue involving global warming and the survival of these majestic underwater ecosystems, but others do exist, and should not be ignored. As climate change worsens, El Niños continue to become stronger, and so do their effects on the living world. Some, as we have learned, may still not even be discovered.

Therefore, it is crucial to remain diligent when attempting to quantify and study the adverse challenges presented by global warming. Coral reefs can only be saved through mass cultural understanding, both by experts, and members of the community (like YOU!). If we are to combat the growing strength of ENSOs in the coming decades, it starts with the small things, including comprehending the gravity situation we are confronted with.

References:

1- “El Niño prolongs longest global coral bleaching event.” News and Features – NOAA, pub. online 23 Feb. 2016. Web. 20 Feb 2017. http://ift.tt/2lkdLLM

2- Eghbert, Elvan A., et al. “Coral Mortality Induced by the 2015-2016 El-Niño in Indonesia: The Effect of Rapid Sea Level Fall.” Biogeosciences, vol. 14, no. 4, 2017, pp. 817-826. SciTech Premium Collection. http://ift.tt/2pIvJYK, doi:http://ift.tt/2lyjNIR

3 – Lindsey, Rebecca. “Global impacts of El Niño and La Niña.” Climate.gov – NOAA, pub. online 9 Feb. 2016. Web. 20 Feb. 2017. http://ift.tt/1Tb8jVF

 

 

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Coral Reefs: Guardians of the Coast

 

One aspect we typically don’t think about with regards to how coastal economies survive, is the longevity of the land itself. Beaches and other coastal areas are constantly changing under erosion, and if these places do not receive the proper protection, the land could disappear over time, taking with it many people’s livelihoods.

This is where coral reefs come in. Last time, I discussed ecotourism, an important producer of revenue for many coastal economies surrounded by reefs. Another important economic service coral reefs provide coastal economies with is protection against erosion, although it’s not just economies at stake. Somewhere upwards of 30 million people live on low coral islands and atolls, and the disappearance of these land masses would mean millions of people being uprooted from their homes, giving coastal protection programs even greater significance (Image 1).

Image 1. Low-lying islands and reefs of Kwajalein Atoll in the Marshall Islands.
Credit: Curt Storlazzi/USGS
(Source: http://ift.tt/2pIZuLU)

It has been found that live corals, along with seagrasses and mangroves, protect coastal areas more than any single habitat or combination of habitats1. Corals specifically, have been shown to limit the impact of waves and storms on coastal areas1, protecting them in the long term. Even more good news, reefs near coastal areas can potentially reduce wave height by up to half a meter in some locations2. This reduction in wave height could significantly reduce erosion on a land mass over time. Although it does not completely put erosion to a stop, it extends the time that the area will be habitable by human populations living there and bringing in revenue from the resources off the coast.

One large factor in whether it is worth maintaining reefs near coasts for the protection they provide is cost. Fortunately, natural defenses for the coast, such as reefs and mangroves, are two to five times cheaper than manmade breakwaters2. This is hugely important because no matter how effective reefs are in protecting coastal areas, and subsequently, their economies, if it is not financially feasible, it will not be done.

Image 2. Artificial reefs being prepared to be stationed near the coast of Riviera Maya in Mexico.
(Source: reefball.com)

In areas particularly prone to large storms and hurricanes, even artificial reefs have been shown to effectively defend coastal areas, although currently, it is not known how to help these reefs last and support life long-term(Image 2). However, because studies have consistently shown that coral reefs provide significant shelter to coastal areas from frequent erosion, I think it is well worth it for coastal economies to invest in the protection of reefs, if not for the reefs’ sakes, but for their own.

 

References
1 Guannel, Greg, et al. “The power of three: coral reefs, seagrasses and mangroves protect coastal regions and increase their resilience.” PloS one 11.7 (2016): e0158094.

2 Narayan, Siddharth, et al. “The Effectiveness, Costs and Coastal Protection Benefits of Natural and Nature-Based Defences.” PloS one 11.5 (2016): e0154735.

3 Silva, Rodolfo, et al. “An artificial reef improves coastal protection and provides a base for coral recovery.” Journal of Coastal Research 75.sp1 (2016): 467-471.

4American Geophysical Union. “Climate change reduces coral reefs’ ability to protect coasts.” ScienceDaily. ScienceDaily, 22 July 2015.

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