The Reefgeneration Organization
For the Future of Coral Reefs
Why Reefs Are In Danger
Coral reefs are shrinking. This is largely due to accumulated human induced stresses. Including:
Destructive fishing practices:
These include cyanide fishing, blast or dynamite fishing, bottom trawling, and muro-ami (banging on the reef with sticks). Bottom-trawling is one of the greatest threats to cold-water coral reefs. These methods do not target specific fish species, they destroy everything within their range.
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Overfishing:
This affects the ecological balance of coral reef communities, warping the food chain and causing effects far beyond the directly overfished population.
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Careless tourism:
Careless boating, diving, snorkeling, and fishing happens around the world, with people touching reefs, stirring up sediment, collecting coral, and dropping anchors on reefs. Some tourist resorts and infrastructure have been built directly on top of reefs, and some resorts empty their sewage or other wastes directly into water surrounding coral reefs.
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Pollution:
Urban and industrial waste, sewage, agrochemicals, and oil pollution are poisoning reefs. These toxins are dumped directly into the ocean or carried by river systems from sources upstream. Some pollutants, such as sewage and runoff from farming, increase the level of nitrogen in seawater, causing an overgrowth of algae, which 'smothers' reefs by cutting off their sunlight.
Sedimentation:
Erosion caused by construction (both along coasts and inland), mining, logging, and farming is leading to increased sediment in rivers. This ends up in the ocean, where it can 'smother' corals by depriving them of the light needed to survive. The destruction of mangrove forests, which normally trap large amounts of sediment, is exacerbating the problem.
Coral mining:
Live coral is removed from reefs for use as bricks, road-fill, or cement for new buildings. Corals are also sold as souvenirs to tourists and to exporters who don't know or don't care about the longer term damage done, and harvested for the live rock trade.
Increase in Atmospheric CO2, The Greenhouse Effect, and Global Warming:
Corals cannot survive if the water temperature is too high. Global warming has already led to increased levels of coral bleaching, and this is predicted to increase in frequency and severity in the coming decades. Such bleaching events may be the final nail in the coffin for already stressed coral reefs and reef ecosystems. The increase in atmospheric CO2 also causes ocean acidification, which is detrimental to coral reefs.
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What is Coral Bleaching?
Coral bleaching occurs when the symbiosis between corals and their symbiotic zooxanthellae (algae) stops, resulting in the loss of these microalgae and rapid bleaching of coral host (hence the term “bleaching”). This is a stress response by the host which coral can be caused by various factors, but the most common and most serious cases are caused by an increase of the surface temperature.
Coral reef bleaching is commonly predicted in relation to the highest monthly average sea surface temperatures. Donner predicted the number of 2°C above normal heating months over ten-year periods up to 2100, under a range of hypothetical greenhouse gas levels, to predict the severity of coral reef bleaching.
Simply due to greenhouse gases that are already in the atmosphere, severe coral reef bleaching will happen every year in half of the world's coral reefs by the year 2080. Some regions of the world, such as the Caribbean, will be affected less than others, such as the equatorial Pacific.
Frequent coral reef mass bleaching by 2030 is predicted even if greenhouse gases are stabilized at 550 parts per million; only natural or artificial enhancement of the temperature-resilience of coral reefs will delay frequent bleaching until at least the year 2100 under these conditions. However, in the "business as usual" scenario (700 parts per million), over 80% of the world's coral reefs will still experience frequent bleaching by the year 2100.
The visual result of coral bleaching:
(click image to enlarge)
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What is Ocean Acidification?
The decreasing pH of ocean water caused by the absorption of carbon dioxide from the atmosphere. Although the natural absorption of CO2 by the world’s oceans helps mitigate the climatic effects of CO2 emissions, it is believed that the resulting decrease in pH (ie making acid water) will have consequences negative, especially for oceanic calcifying organisms such as coral reefs. With increased CO2 output into the atmosphere caused largely by human activity, the oceans have been absorbing larger and larger amounts of CO2. This means that humans may be a direct cause of acidification at an unnatural rate.
