Reefs cannot live in cold waters and are limited by ocean depth and available sunlight. Coral is the foundation of the reef community, providing a three-dimensional structure where thousands of species of vertebrates and invertebrates live and feed. Some species of coral are hard, while others soft.
Coral reefs lives in colonies consisting of many polyps using living tissues to connect to each other. Each polyp resembles a cupcake shape with a circle of tentacles near the opening. To capture zooplankton for food, the tentacles are equipped with stinging cells for trapping. The small polyps secrete limestone, also known as calcium carbonate. The exoskeleton of the coral is made of these secretions, just like the shell of a snail. Reefs are able to grow from the stone. The algae that live in the corals use the process of photosynthesis, taking sunlight to converts water and carbon dioxide into sustenance. The polyps receive most of their energy this way, although they are carnivorous. For providing the corals with energy, the algae are provided shelter to live, taking the coral waste for their own growth. A situation where two organisms live together gaining benefit is called mutualistic symbiosis.
The poor water quality is attributed to the inflow of chemical effluents that pollute the water and endanger the lives of most organisms. In addition, they raise nutrient levels necessary for the growth of crow-of-thorn starfish. Coral cover within the Great Barrier Reef is evidently declining, and thus fast mitigation is necessary to safeguard the listed World Heritage area in Australia. Given the procedural work in enforcing such measures, it is unlikely to have impacts in the short term (Veron, 2008). However, direct action is not only necessary but also required to minimize the growth of crown-of-thorns starfish and extra loss of corals. Nevertheless, with or without improved mitigation, the coral cover will continue to decline mainly because past activities have majorly increased ocean temperatures and seawater acidity. Marine life may not necessarily decline, but the severe conditions will compel the living organisms to adjust to new modes of survival since the food web will be distorted. This situation will tamper with the atmospheric cycle. Carbon entering the atmosphere will no longer be sufficiently absorbed in the water bodies, thus increasing air and water pollution (Watson, 2011).
In light of the rapidly increasing temperatures, coral species face an uphill struggle to adapt, evolve and survive. Although corals and their symbionts have the abilities to resist the temperature changes, one can only wonder the extent and effectiveness of these strategies.
De’ath, G., Fabricius, E., Sweatman, H., & Puotinen, M. (2012). The 27–year decline of coral cover on the Great Barrier Reef and its causes. PNAS, 109 (4), 17995-99.
Pyers, G. (2011). Biodiversity of coral reefs. New York, NY: Marshall Cavendish Benchmark.
Sweatman, H., Delean, S., & Syms, C. (2011). Assessing loss of coral cover on Australia’s Great Barrier Reef over two decades, with implications for longer-term trends. Coral Reefs, 30, 521–531.
Veron, J. (2008). A reef in time: The Great Barrier Reef from beginning to end. Cambridge, MA: Belknap Press of Harvard University Press.
Watson, M. (2011). Coral Reefs. Encyclopedia of Environmental Issues, 1(4), 317-319.