Question

Please choose an environmental topic of your choice and read/research the topic and write a short 3-4 page essay outlining the key areas of the topic/issue. This is a topic that you would like to learn more about so that you can share that information in your essay.

The essay should contain:

Title

Introduction - include a brief introduction to the topic, indicating the key areas and why you are interested in the topic/issue.

Body - You should include all of the key areas from the introduction, with supporting information.

Conclusion - You will want to wrap your paper up with a conclusion that includes your views on the topic/issue and how you think the topic or issue should/could be addressed.

References - You will want to include all references in a reference section. You must have at least two references, text, journal, paper, or other.

Answer 1

Climate change and coral reef ecosystems

Introduction

Anthropogenic activities have increased the emission of greenhouse gases on earth. Increase in greenhouse gases in the atmosphere result from burning fossil fuels for heat and energy, industrial operations and deforestation. Increase in the greenhouse gases cause increase in atmospheric temperature and warming. Increase in concentrations of gases such as carbon dioxide cause climate change and ocean acidification. Oceans act as a massive sink that absorbs carbon dioxide (CO₂).

Coral reefs are one of the most productive ecosystems on Earth. Coral reefs benefit the environment and people in numerous ways. They provide many services such as fisheries, shoreline protection, tourism, and medicine. According to World Meteorological Organization, the goods and services provided by the tropical coral reefs account for the amount for more than US 30 billion dollars annually. Coral reefs support plant biodiversity on the planet. They cover an area of over 280,000 km² and support many species. They protect shores from the impact of waves and from storms and provide economic benefits to people from tourism.

Causes and effects

Coral ecosystems are sensitive to changes in environmental conditions. Climate change will affect coral reef ecosystems through increase in sea level, changes in the frequency and intensity of tropical storms and altered ocean circulation patterns. All these effects have great impacts on the ecosystem function. Rise in temperature or warming causes thermal stress leading to mass bleaching of corals and increase spread of infectious diseases. Rise in sea surface temperature can cause coral to lose their symbiotic algae that is essential for the nutrition and color of corals. The death of the algal partner makes the coral to appear as white or “bleached." change in the water temperatures by even one degree Celsius can also lead to coral bleaching (Goreau and Hayes, 1994). High temperature cause physiological damage to corals (Wilkinson et al., 1999).

Increase in carbon dioxide absorption by ocean from the atmosphere reduce calcification rates that alters reef-building and survival of reef-associated organisms as the water chemistry gets affected mainly by decrease in pH. The process is referred as ocean acidification. Rise in sea level increases sedimentation leading to smothering of coral. High intensity storms destroy the coral reef structures. Alterations in the pattern of precipitation, increased water runoff, sedimentation lead to production of algal blooms that obstruct light availability. Changes in the ocean temperature regimes reduce the availability of food to corals preventing their proliferation and spread. Acidification of ocean caused due to increase in CO₂ cause reduction in pH levels. This decreases coral growth and structural integrity.

               Research studies have shown that coral bleaching has been noted at 100 different locations around the world during the tenure of 1980 to 2016. The rate of bleaching has increased more than fourfold in the last few decades. In most of the sites, it is mainly caused due to warming of ocean waters. Coral reefs around the world experienced the most extensive and severe bleaching in the year 1998 (Wilkinson et al., 1999). Bleaching was reported in 60 countries and island nations at sites in the Pacific Ocean, Indian Ocean, Red Sea, Persian Gulf, Mediterranean and Caribbean. Corals of the Indian Ocean were severely impacted and showed mortality greater than 70%. Most of which was reported from Maldives, Andamans, Lakshadweep Islands, and Seychelles. The mass bleaching occurred because of anomalously high sea surface temperatures (Strong et al., 1998). Mass bleaching was also linked to El Niño-induced seawater warming for many parts of the Pacific ocean.

           The projected increase of global mean sea-surface temperatures by 1-2°C in the next century is supposed to cause increase in overall warming accompanied by more frequent storms and alterations in precipitation patterns. This is likely to increase mass bleaching events. Besides this   increasing human activities such as overfishing, pollution, soil erosion are also likely to damage the coral reef ecosystems (Hodgson, 1999; Nurse et al., 1998). Ocean warming along with rise in sea level and increased frequency of storms and El Niños are also predicted to cause coastal erosion, sedimentation, and turbidity that will affect the survival of coral reefs in the long run. This has raised concerns about the coral reefs throughout the world. If we wish to save coral reefs we need to protect them from threats such as excessive coastal development, overfishing pollution (land and water), global climate change and reduction in emission of greenhouse gas emissions.

Conclusion

We need to take steps to protect and conserve coral reef ecosystems for the of the maintenance of the ecological interegrity and sustanence of dependent communities.

References

Goreau, T. J. and R. L. Hayes, 1994. Coral bleaching and ocean "hot spots." Ambio 23, 176-180.

Hodgson, G., 1999. A global assessment of human effects on coral reefs. Marine Pollution Bulletin 38, 345-355.

NOAA. 1999. Climate of 1998 annual review: global temperatures. National Climate Data Center. 12 January 1999. http://www.ncdc.noaa.gov/ol/climate/research/1998/ ann/global_temperatures.html

Nurse, L.A., R. F. McLean, and A.G. Suarez, 1998. Small island states. In The Regional Impacts of Climate Change: An Assessment of Vulnerability, 331-354, (Eds RT Watson, MC Zinyowera, RH Moss), Cambridge University Press, Cambridge, UK.

Strong, A. E., T. J. Goreau and R. L. Hayes. 1998. Ocean Hot Spots and coral reef bleaching: January July 1998. Reef Encounters 24, 20-22.

Wilkinson C, O. Linden, H. Cesar, G. Hodgson, J. Rubens, and A.E. Strong, 1999. Ecological and socioeconomic impacts of 1998 coral mortality in the Indian Ocean: An ENSO impact and a warning of future change? Ambio 28, 188-196.

Suggested readings

An Introduction to Coral Reefs - An introduction to coral reef ecology by the University of the Virgin Islands. http://www.uvi.edu/coral.reefer/index.html

Brown, B.E., Odgen, J.C. 1993. Coral bleaching. Scientific American 269, 64-70.

Status of Coral Reefs of the world: 1998 Electronic version of a report on the status of coral reefs in 1998, including a detailed chapter on the 1997-98 bleaching event. http://www.aims.gov.au/pages/research/coral-bleaching/scr1998/scr-00.html