Under Water Desert
- Gulsen Unveren
- Nov 11, 2019
- 2 min read
Coral reefs have been present on earth for 100s millions of years but the 21st century could be their last. The coral reefs, stunning with their wild beauty, have been trying to survive through global warming and high rates of climate change. However, when it comes to increasing temperatures, a few degrees change is the line between life and death for coral reefs. Coral reefs are critical to the ecosystem and have been facing serious declines with 30% of corals already severely damaged and 60% is expected to be lost by 2030 if the current rate of environmental change were to persist.
Corals are highly dynamic ecosystems, consisting of a combination of animals, plants and minerals. The relation between increased greenhouse gases, climate change and regional bleaching of corals has become undeniable over the course of the last 10 years with the mass bleaching of Great Barrier Reef corals through the 2016 heatwave. Increasing atmospheric carbon dioxide levels are expected to alter the chemistry of oceans which in turn could result in a reduction of accretion of coral reefs. Bleaching has become the most pressing consequence of climate change and has been increasing in intensity over the past 30 years.
Corals require algae for survival through a symbiotic relationship. While algae survive through the CO2 supplied by the coral, coral consumes a large number of sugars that are supplied by algae through the process of photosynthesis. This vital, solar-powered partnership, however, is highly dependent on the temperature for survival. Above 30°C algae lose its ability to photosynthesise and excessive solar energy results in the formation of reactive forms of oxygen such as peroxide. The chemical changes within the corals compromise the health and corals become prone to infectious bacterial attacks preventing the recovery of corals.
The spread of global bleaching has been present in the oceans since 2014 caused by elevated temperatures during recurrent ENSO (El Nino-Southern Oscillation) events. The high temperatures of 2014 were exceeded in 2016, 2°C warmer than ever recorded. Extreme temperatures than lead to mass bleaching of northern Great Barrier Reef, resulting in the destruction of 800 km with 80% of the corals being bleached. However, increasing temperatures are not the only threat to the survival of the coral reefs. Increasing frequency and intensity of storms has been shortening the recovery time for the corals, preventing recolonisation. Coral reefs have a high geographical range which is complemented by the high genetic biodiversity of coral species. Especially, coral species in the Arabian Gulf can survive under temperatures as high as 36°C. Genetic variations of coral reefs have been under the focus of scientists hoping to increase the adaptation rates of coral reefs.
The ABC Science documentary "What is coral bleaching? Can it be fixed?", focusing on 2016 bleaching event of Great Barrier Reef is a must watch to capture the true scale of natural destruction. The documentary achieves to explain scientific concepts with a simple language through the appearances of experts in coral ecosystems, including Prof. Terry Hughes.
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