Coral Reef Deforestation

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In 2015, half of the global population was predicted to be living near the coast and therefore increasing human impact on reef systems, both positive and negative. There are five main negative impacts that humans are currently having on reef systems worldwide. They are overfishing, deforestation, coastal development, coral disease and pollution.

Overfishing, and other destructive fishing practices have been identified for a very long time as the most pervasive out of all local threats facing coral reefs. More than half of the world’s reefs are threatened by overfishing and this increases to 95% of reefs affected in South East Asia, most likely as a result of blast and cyanide fishing. Reef fisheries are a vital source of food, and a way of
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The sedimentation and pollution as a result of this is detrimental for coral reefs and its surrounding habitats. As greater amounts of land are cleared for agricultural and coastal development, a great deal of the sediment loads and nutrients are running into the ocean and assimilating into coral reef environments. As a result, many coral fall victim to “rapid coral death by deadly chain reaction’ if sedimentation is not removed. The fine particles which compose soil sedimentation, reduce the amount of light that corals are able to access and utilise for photosynthesis. For the coral in most cases, this means death by starvation and therefore drastically decreasing coral cover over a long period of time. A group of German researches carried out an investigation and found that when a two millimetre layer of sediment covers the corals, algae will stop the process of photosynthesis as they are no longer able to reach the light. They also found that this lack of oxygen and acidic living conditions, created irreversible coral tissue damage in some parts. The dead coral matter are digested by microbes, which produces a compound potentially fatal to all other corals – hydrogen sulphide. Hence the “rapid coral death by deadly chain reaction” which if the conditions are bad enough, can occur in under 24 …show more content…
Just recently, the Acropora species in and around the Caribbean reefs were completely wiped out by coral disease. Sea surface temperatures are increasing as a result of climate change and this is having two huge impacts on reef systems. Firstly, an increase in temperature encourages infectious diseases. The increase in temperature impairs the coral’s defence mechanisms. A normal coral’s immune system should be able to identify and respond to specific pathogens however an increase in temperature affects their basic biological and physiological properties making them unable to fight infection. An increase in ocean temperatures also increases the growth rate of disease causing organisms. There is further evidence from the Great Barrier Reef, to make a correlation between warming ocean waters and disease outbreaks, in that coral disease prevalence increased from winter to summer in all major families of coral. As stated before, coral disease is also instigated by insufficient water quality particularly due to eutrophication and sedimentation. Corals are only suited to cope with certain mild and controlled levels of nutrients in the water, as result when the water becomes too rich in nutrients, this has been found to accelerate disease signs in corals as well as significantly

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