Coral Reefs and the Ecological Web

The world's oceans are a massive resource to the inhabitants of the planet. Aside from providing earthlings with a food source, oceans aid in nutrient cycling, provide a habitat for all of the organisms that live within them, and even affect the weather. However, the ecosystems within the ocean are changing. As we know from ecology, a change in one part of the ecological web can have unforeseen effects elsewhere. This is why it is important to maintain the current ecological function of all parts of the biosphere. It is no secret that the coral reefs of the world are in danger, but the problem doesn't end with corals. The destruction of coral reefs from anthropogenic causation can affect the balance between prey and predator in many ways.

Healthy coral reefs are made up of many organisms functioning in close proximity. Corals are made up of polyps that secrete limestone to give themselves a protective coating and the skeletons join together to form the reef. The hard reefs produced by the polyps also act as a natural barrier to protect beaches from high waves and produce sand for the beaches by means of natural erosion. Besides the actual coral polyps that live within the corals, there are many more inhabitants of coral reefs. These organisms include algae, sponges, worms, starfish, sea urchins, lobsters and fish according to UNESCO's website. However, providing a habitat for these creatures is only one of the multitudes of purposes they fulfill.

Another function of corals includes participating in precipitation cycles. They everyday processes of various corals produces chemicals that are then transported to other areas of the biosphere. According to Dr. Graham Jones in an articles entitled, Healthy Coral Reefs Produce Clouds and Precipitation, "Coral reefs produce a volatile substance called dimethylsulphide or DMS which oxidizes in the atmosphere to produce cloud condensation nuclei. These are tiny sulfur aerosol particles around which water vapor condenses to form clouds. Water vapor cannot form clouds without these tiny aerosol particles being present (CCN)." The many functions of healthy coral reefs are important to preserve. However, the quick degradation of them, mainly by global warming and the negligence of humans, will detrimentally impact the efficiency of the functions also.

Global warming affects coral reefs by warming the oceans. As the temperature changes, polyps may not be able to produce limestone as well. This reduction in limestone production means that less coral reef would be formed, which is a problem because it would effect protection for fish and the rate coral reef and beach erosion occur, among other ecological changes. According to an article from Nature News, "15% of corals are beyond repair because of global warming and an additional 30% could be lost over the next 30 years." The science in regard to global warming now overwhelmingly points in the direction of human causation. Nevertheless, a more direct example of how humans are killing coral can be found in the Caribbean and other tropical areas. Vacationers in these areas often apply sunscreen at the beach, and when they enter the ocean, this sunscreen is subsequently washed off. The chemicals within the sunscreen that protect against UV, also happen to generate viral infections which attack the microalgae that live in close association with the corals. This causes the corals to lose an essential source of nutrients when microalgae die and also causes bleaching on the coral itself.

Currently, corals have many environmental stressors forcing them to adapt quickly or fall victim to natural selection. One of the stresses the algae are facing comes in the form of food. As oceans warm and coral shed algae, they are also shedding a vital nutrient source. The symbiotic microalgae live side-by-side with the coral, and they are an important part of a healthy coral reef. With the lack of a nutrient source, the coral have no choice but to attempt to switch food sources, so they go fishing. The coral begin to catch small marine life such as zooplankton, which they can use to derive essential nutrients. Changes such as these can have alternate effects outside of their interaction. With a depletion of zooplankton in the ecosystem, other organisms that rely on zooplankton may find themselves stressed for food. This could cause further ecosystem changes when other animals begin to switch food sources, which can result in population crashes if the organisms cannot find a suitable food source soon enough.

The same fish that can be affected by the food source changes of corals can also be affected by the bleaching of corals. Healthy coral are vibrant and come in a variety of colors. These colors allow tropical fish to camouflage themselves and seek refuge from prey. Unfortunately, microalgae deaths, such as those caused by sunscreen chemicals and the ocean's rising temperatures, are causing corals to become bleached. This bleaching strips the coral of its color and additionally, eliminates one of the protective characteristics of healthy coral reefs. This loss of sanctuary for marine life means increased predation. This could result in population flourishes for the predators that suddenly find great ease in capturing prey, and it can mean devastating population crashes as a result of an organism's difficulty hiding from predators.

Anthropogenic stresses on the biosphere are causing the ecosystem to lose its balance and stability. The pumping of chemicals into the atmosphere alters the number of greenhouse gases that can reflect solar radiation. This, in turn, leads to more heat being trapped in our atmosphere. When the heat begins to warm the oceans, it affects the way organisms function within it. This drives natural selection to eliminate the organisms that cannot keep up with the changes. The balance of the entire biosphere rests on the ecological web of organisms working to transform and exchange elements. The host of organisms that are affected by the simple change in the efficiency of corals is a testament to the interconnectedness of the ecological web.

The earth is changing everyday, partially for natural reasons, partially for anthropogenic reasons. These modifications are echoing throughout the biosphere and manifesting themselves by shifting the ecological web. The variations that corals face are adjusting the natural predator-prey relationships within our oceans. The unstable population crashes of microalgae that live in symbiotic relationships with coral are a sign of a large biological stressor, and if a solution to the coral's degradation is not found, we may lose the beauty, efficiency, and abundance of the world's coral reefs.

Works Cited:

Brown, Susan. "Sunscreen wipes out corals" Nature News. 29 Jan 2008. 6 Apr 2010. http://www.nature.com/news/2008/080129/full/news.2008.537.html

Hance, Jeremy. "Healthy coral reefs produce clouds and precipitation" Mongabay.com. 3 Mar 2010. 25 Apr 2010. http://news.mongabay.com/2010/0303-hance_coralclouds.html

Hopkin, Michael. "Corals go fishing to survive" Nature News. 21 Oct 2009. 6 Apr 2010. http://www.nature.com/news/2009/091021/full/news.2009.1023.html

Pearson, Helen. "Global warming threatens coral reefs" Nature News. 16 Feb 2004. 6 Apr 2010. http://www.nature.com/news/2004/040216/full/news040216-3.html