Recent studies have found that the world’s coral are in considerable danger of disappearing due to a number of environmental pressures. These pressures include fishing, pollution, disease, global warming and ocean acidification. Overall, an estimated seventy-five percent of the world’s coral reefs are at risk. Global warming and ocean acidification are a growing problem, a problem which is only expected to be heightened as the century progresses.
The natural pH of seawater is 8.2. Since the industrial age, the pH of the world’s oceans has decreased by 0.1 down to 8.1. The world’s oceans have absorbed approximately half of all carbon dioxide emissions which have been emitted across the globe. Some studies have found that the world’s oceans are upwards of twenty-five percent more acidic today than it was prior to the Industrial Revolution. As carbon dioxide emissions are continuing to increase, the problem is only expected to worsen for the world’s oceans and coral reefs.
In addition to dealing with rising acidification, the world’s oceans and marine animals are also having to deal with increasing temperatures. Coral bleaching is often the result of increased temperatures, a process which can ultimately kill off large areas of reefs year to year. Pollution also contributes to coral bleaching as well and is often most predominant along major coastlines with agricultural, industrial and sewage waste.
An Australian study published last month in the journal Proceedings of the National Academy of Sciences analyzed coral of the Great Barrier Reef. The researchers determined that the coral reef coverage has declined by approximately fifty percent since 1985. What is more concerning is that two-thirds of the coral coverage reduction has been since 1998.
Climate change has been a major impact of recent declines of coral in the Great Barrier Reef, but scientists wanted to analyze the impact human populations have made on the reef prior to significant climate impacts. Published in the journal Proceedings of the Royal Society B, scientists determined major changes to the reef occurred earlier in the 20th century due to increasing human settlements in Australia.
The influx of European settlers to the Queensland area in the 1860s appears to have greatly impacted the surrounding waters. The impact appears to have become more prevalent in the 1930s with the use of fertilizer and pesticide. These chemicals even today enter the waters and are said to essentially poison the coral. In addition, scientists believe that this runoff then triggered algae blooms which then impeded any chance of the coral from growing once more.
Australian scientists analyzed sediment cores which were taken from off the coast of Queensland. By dating the levels of the core, the team determined that a significant species stopped growing between 1920 and 1955. The Acropora coral species was prevalent in the region until this time, when the aforementioned runoff is thought to have killed the species. The species was likely home to a number of marine species as the upwards of sixteen feet in height by sixty or more feet in width could offer shelter to many. The species would also have acted as protection for the shore. Once this coral was choked out, the Pavona species began growing. This species is much smaller and would not be as suitable for shelter or storm resistance.
The scientists concluded that human impact on coral has been ongoing for more than a century. The authors of the study indicated that water quality needs to be addressed as a major issue. If water quality were to improve the scientists believe the reefs would have a chance at recovery. However, the impact of climate change may hamper any improvements in water quality.