Evaluate the Relative Importance of Global and Local Threats to One Named Global Ecosystem

Evaluate the relative importance of global and local threats to one named global ecosystem (15 marks)

Coral Reefs are a unique ecosystem, which usually grow in conditions where the temperate is around 24c and in less than 25m depth of water. Coral reefs are homes to over 25% of known sea creatures and are an invaluable service for the local population as a source of food and income. Coral Reefs are under huge stress due to the impact that human activities are having and in fact already 1/5 of the world’s coral reefs are so damaged that they are beyond repair.

A global threat, which is affecting all fragile ecosystems, including coral reefs, is global warming. Firstly, the average increase in global temperatures is leading to an increased rate of ice cap melting. The melting of the ice caps releases more fresh water into the oceans, reducing salinity. The increased water volume is also increasing sea level rise; coral reefs find it difficult to survive in over 27m depth of water. The increase in sea temperatures can also change the nutrient flow. Coral bleaching is a devastating side effect of global warming which affects the corals. Coral bleaching is permanent damage and is occurring globally. The effects of the bleaching are worsened during El Nino years; in 1990 almost 50% of the worlds coral reefs were severely damaged. The most damaged reefs were in the Persian Gulf where 65% had been destroyed, followed by reefs in South Asia where 45% and 38% respectively, were considered destroyed. The Great Barrier Reef in Australia also witnessed a bleaching of 60-95% of the corals. A similar coral bleaching event occurred in 1982-83 when 95% of the coral in the Galapagos Islands was bleached.

Coral Reefs can be damaged by invasive species however these problems occur on a more local scale. Lionfish are rapidly increasing in numbers throughout Atlantic and Caribbean reefs, these fish are venomous, eat high quantities of fish and breed rapidly, this results in an...