March 6th, 2018
The destruction of coral reefs is a larger threat to tropical coastlines than higher sea levels, according to a new international study.
The research published in ScienceAdvances found that tropical coastlines are at a greater risk of erosion from larger wave heights after live coral has been destroyed.
Coral reefs are the most diverse marine ecosystems on Earth and provide ecosystem services for millions of people.
The study examined the wave processes of coral reefs in Moorea and Tahiti in French Polynesia and modeled future wave heights near the coastline by looking at coral reef health and sea level.
The results demonstrated that wave heights in regions with coral reefs will increase on all sites analysed at the French Polynesia.
The researchers predict that wave heights will likely be twice the size of the current ones in such locations and in other reef sites worldwide by the end of the century.
“The study shows that you don’t need higher sea levels for there to be coastal erosion, just the loss of healthy coral reefs,” said Dr Daniel Harris, one of the study`s authors.
Coral bleaching at Heron Island Feb 2016 Photo: The Ocean Agency / XL Catlin Seaview Survey / Richard Vevers
According to the study, preserving the structure of coral reefs in scenarios of high sea-levels helped reduce wave heights by three times.
Although the reefs in French Polynesia showed a remarkable capability to recover from the likes of cyclones and coral bleaching, future degradation seems likely based on current global trends.
Though the results were focused on reefs in Tahiti and Moorea, they also serve as an example of what could happen to other coral reefs due to high sea levels and reduced coral cover.
“The findings suggest that actively maintaining the health of coral reefs could reduce some of the negative impacts of sea level rise on tropical coastlines,” said researcher Dr Alessio Rovere.
According to Dr Harris, the findings demonstrated the need for authorities and scientists to include measurements of the health of coral reefs when analysing the risk of erosion to tropical coastlines.
According to the research, further support for preventing the destruction of coral reefs is necessary, especially regarding the reduction of greenhouse emissions.
The current rate of coral bleaching is happening faster than in any other era in history, with a recent study in the journal Science finding that the frequency of bleaching is undermining the capacity of coral reefs to recover and is threatening their very existence.
Coral bleaching occurs where corals expel crucial algae living symbiotically within their tissues as a stress response to increasing ocean temperatures. When bleaching is severe and prolonged, many of the corals die and it can take several decades for new coral to grow back.
The study from the ARC Centre of Excellence for Coral Reef Studies (CoralCoE) measured the bleaching rate at 100 globally distributed Coral Reefs from 1980 to 2016. The results pointed to a significant decline in the time frame between bleaching events, dropping to only six years.
