Coral Reefs Part 2: Our ever changing climate

The complexities of coral reefs, as we all know is not just affected by sedimentation as discussed in part 1. In fact it is just a small piece of a larger puzzle. Sedimentation is the direct result of removing forests and increasing outflow on reefs, and or because of dredgers putting fine sediment in suspension, which then drifts on reefs. Rather worryingly post me writing part 1, I noticed a similar issue of dredging taking place in the Cayman Islands. Let’s hope that the Australian government aren’t the only ones to implement legislation to stop this from happening. The next topic of Global warming, is completely separate, but still the result of the human races heavy reliance on fossil fuels. The last installment looks at fishing and their importance in a reefs ecosystem.


The energy from the sun is vital for the coral reefs to survive. Algae that are found in the corals provide over 80% of the energy with the remainder being made up by the polyp itself, filtering food particles from the water. This need is often a curse exasperated by the human impact of global warming. With greater sunshine and greater warming linked to carbon dioxide (greenhouse gas) the corals become stressed and sometimes expel the algae. This causes the coral to go the ghostly white termed bleaching because the algae house the fantastic colours and pigmentation. As you can imagine with over three-quarters of the corals food supply being removed, it doesn’t take long for the corals to perish. These bleaching events are also exasperated by the El Nino events, when increased naturals warming coincides with manmade global warming, having catastrophic consequences for reefs.


Bleached coral lacking its symbiotic zooxanthellae due to ocean warming


Not only is the burning of fossils fuels warming the seas because of the greenhouse effect, they are also mildly acidic. The sea naturally absorbs anthropogenic CO2, attempting to balance out the high concentrations in the atmosphere. It is a natural heat sink, the main cause of bleaching, but it also tries to sequester CO2 from the atmosphere. This effect is a good thing for anything above the water as the global warming effects will be slight or limited because so much absorbs in the sea. However this increase in CO2 reduces the pH and disrupts the chemical balance of many calcifying processes that take place in reefs. This negative effect will make it more difficult for corals to grow and develop.

Sea level rise

Now that we have stepped into a greenhouse world, with acidifying oceans the next complication is sea level rise. With increased temperature comes the melting of the ice caps and the glaciers. Shallow land areas and coastal areas will soon be engulfed in several years by ever rising tides because of ice caps melting. This also has severe implications for global reefs. These are solid structures that make their homes in the photic zone from 3-20m. With more fresh water comes sea level rises, which can result in some corals being outside the most productive zone. An estimated that there will be a global rise of up to 1m by 2100, which added with acidification and warming could be the last straw for some reefs.


I wanted to cover the plight of coral reefs for different reasons. Mainly because I think there breath-taking, but also the issues they face is often lost in translation. It is often mixed with global warming and its consequences. Sometimes it is challenging to propagate the reasons why global warming will affect Coral reefs. All of the problems thrown at coral reefs, it is not just one issue, but a combination of them all. With warming oceans you have bleaching, which can recover, however with acidification, sea level rise and others makes it more difficult for them to recover and regain the algae, which they desperately need. I guess all I wanted was to open people’s eyes to their beauty, maybe to inspire you to go dive in them. Being a diver myself, it is amazing what varieties of fish and the colours of corals you can see. I want everyone to see them for themselves.


Beautiful display of corals mixed with tropical fish. A marvelous site to see for yourself.

Previously I spoke of sedimentation, the choking of reefs; this can easily be prevented. The example of the Cayman Islands to allow larger ships in shallow areas are harmful to tourism given by the coral reefs. If conservationists and industry were to work together, talking about the problems and alternatives maybe reefs stood a chance. The same story applies for global warming but obviously on a larger more complex scale. With more CO2 and more warming, the outcome will result with worsening seas for wildlife and us. The sea will always attempt to soak up the imbalances we have created so we must act to help it. Without a healthy ocean everything will perish, making people aware of this is the only way to stop it from happening.

Coral Reefs Part 1

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I am a trained geologist who has a passion for conservation and working with wildlife. I write articles that interest me and that I am passionate about using skills and knowledge to highlight issues related to climate change. I don’t write articles for views, I write them to change views.

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  1. 17th November 2015

    […] Coral Reefs Part 2 […]

  2. 25th November 2015

    […] Coral Reefs Part 2 […]

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