Coral Reef Restoration; one of the Solutions to Climate Changes?

 Lake Urmia- Iran

Climate Change

The average of the weather conditions at a special point on the Earth is called Climate. Climate explains temperature, rainfall and wind conditions based on a historical range. Changing in climate circumstance and to continue for a long period of time is called "climate change". In the period since the Industrial Revolution, human emissions of greenhouse gases from fossil fuel combustion, deforestation and agricultural practices have led to global warming and climate change. Many scientists and researchers argue that climate change threaten planet ecosystems and human civilization destructively. (Riedy, 2019). 

Climate change and human activities are pushing coral reefs in the anthropocene and face unprecedented losses of up to 90% by mid-this century (Williams et al, 2019). Climate changes are reducing coral growth rates that are critical for maintaining reef structure and tracking rising sea levels. Under expectations of continued reef degradation and reassembly in the Anthropocene, urgent actions must be taken to protect and manage the world’s remaining coral reefs.  Given such concerns about the long-term functional erosion of coral communities, one conservation strategy is to prioritize the protection of reefs that currently maintain key ecological functions, such as reefs with abundant fast-growing and structurally complex corals that can maintain vertical reef growth and net carbonate production.


Ocean Acidification and Ocean Warming 

Ocean Acidification and Ocean warming are two important results of climate change. Marine Calcareous Organisms (e.g., corals) and high-magnesium calcite (e.g., coralline algae and echinoderms) that produce calcium carbonate shells or skeletons are negatively impacted ocean acidification. Ocean acidification reduce the ability of reef-building corals to produce their skeletons and calcium carbonate structures in the reef areas, but it also causes the reef framework and sediments to dissolve more rapidly. This leads to a loss of reef structures which supports reef biodiversity, and a loss in reef integrity, which serves to protect shorelines from erosion (Kleypas, 2019). 

 For the past 40 years, the global average surface temperature in land and ocean has consistently been more than the 20th century global average. During warming events, planet species must tolerate the heat stress or die. The most well-known consequence of ocean warming on a benthic species is coral bleaching, the stress-induced expulsion of the symbiotic dinoflagellates (zooxanthellae) that live within the coral tissue. This occurs when water temperatures exceed by 1-2°C the normal maximum experienced by corals, over a period of a few weeks. As result of ocean warming through this century, coral bleaching events becomes too frequent and severe to allow coral reefs to recover themselves, so that the coral reef ecosystem in most major reef provinces is likely to collapse across much of its current range, particularly where other stressors such as humane activities are not controlled (Kleypas, 2019).

 Several studies have been showed that the carbonate production, reef structural complexity, biological diversity, and coral recruitment decreases at a low pH.  Laboratory studies shows in a low pH, the coral recruitment point decreases because of reduction in the compounds produced by coralline algae that attract coral larvae to settle. The studies showed that newly settled coral larvae produce thinner skeletons that become easily broken (Kleypas, 2019).
Photographs of a coral reef ecosystem near a submarine CO2 vent system, showing changes in the coral community structure and reef structure located (a) in normal pH conditions, (b) in pH conditions similar to those projected for the middle of the 21st century, and (c) in pH conditions similar to those projected for the end of the 21st century (Fabricius et al. 2011)

Coral Reef Restoration; one of the Solutions to Climate change?

 The first most important marine ecosystem which is suffering from ecological collapse in this century is coral reefs.  Active reef restoration is increasingly recognized as a way to speed up reef recovery and, when combined with assisted evolution and assisted migration, as a way to restore reefs with corals that are more resilient to climate change (Rinkevich, 2014).


Active restoration has rapidly increased over the past decade within the Caribbean and Mesoamerican reef systems, building on the success in fragment-based propagating and outplanting many thousands of colonies of the threatened species Acropora cervicornis and A. palmata (Young, Schopmeyer & Lirman, 2012; Schopmeyer et al., 2017), to include many other coral species.


Coral restoration efforts on Indo-Pacific reefs have also had marked success (e.g., Montoya-Maya, Smit, Burt & Frias-Torres, 2016), and have fast-tracked the testing of new methodologies for speeding up growth rates and maximizing survival. Such restoration activities, which are carried out in both in-situ nurseries and land-based aquaculture, provide the
platforms for testing and incorporating innovations to accelerate rates of adaptation to rising temperature and acidification, or which reduce the susceptibility to disease (Kleypas, 2019).

A major challenge with active restoration is the scale at which these activities must be carried out. Strategically building the capacity for reef restoration at many locations and across a variety of reef systems is key to achieving that scale, not only in terms of the hectares of reef that can be restored, but in providing benefits tangible to local communities, which is essential to maintaining long-term commitment to the restoration activities. Wilson (1992) prophesized some 25 years ago: “The next century will, I believe, be the era of restoration in ecology.” The future of many marine ecosystems depends on our capacity to not only restore them, but to tackle the root causes of climate change, to understand how marine ecosystems will respond to those changes, and, as is increasingly emphasized, to strongly engage society in their restoration (Kleypas, 2019).