Exceptional coral reefs bleaching events would become the new norm

Exceptional coral reefs bleaching events would become the new norm

Scientists reported a coral reef sector’s exposure to warming as the projected year of onset of annual severe bleaching events, under the ‘business-as-usual’ emissions scenario. 

 

Coral reefs are one of most inspiring ecosystems, with their beauty for tourism, their role in protecting our shorelines from storm waves, and holding the greatest biological marine diversity on earth. 

However, coral reefs are in trouble. They face local threats, such as overfishing and pollution, and the common threat of global warming and seas acidification. As temperatures rise, reef corals experience bleaching which can spread to large sections and lead to death. 

Unfortunately, with future high sea temperatures from climate models, a severe coral bleaching event will happen every summer in the Commonwealth of the Northern Mariana Islands (CNMI) in the northwestern Pacific Ocean. At this point, reefs are expected to have lower biodiversity, habitat quality and ecosystem goods and services that reefs can provide.

Global warming is the most urgent global threat to reefs. The 2014-2016 coral bleaching event was the third recorded coral bleaching event in the world, leading to significant coral death worldwide. 

 How do coral reefs survive without oxygen?

The CNMI reefs underwent severe bleaching in 2013 and 2014, with another more minor event in 2016. The 2013 event seems to have led to a significant coral mortality around CNMI.

 

The situation would get worse, temperature forecast models suggest that this exceptional annual events could become the new norm before next 20 years. So, how can reefs managers react to minimize risks?

A report from NOAA Pacific Islands Fisheries Science Center, Honolulu,  Hawaii and SymbioSeas and the Marine Applied Research Center, Wilmington NC, shed light on what does planning local responses to rising temperatures require?

For this group of researchers, three main questions should be answered:

  • Exposure: when will a given reef face potentially catastrophic warming? 
  • Resilience: how likely is a given reef to resist or recover from high temperature events? 
  • Social Vulnerability: how difficult will it be for the communities that depend on reefs to reduce their reliance on reef resources? 

 

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