What are the threats to Coral Reefs
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| NOAA |
-Growing Acidity in Oceans
Almost a third of atmospheric carbon dioxide is absorbed by the ocean. This was, at one time, seen as positive due to the diminishing effect it has on global warming; however, high levels of carbon dioxide in the ocean lower the pH or increase the acidity, which is harmful to coral. The pH has already dropped a tenth of a unit and might drop up to a third of unit in a hundred years. Soon, the Environmental Protection Agency's recommended acidity levels will be surpassed. The source of the majority of these carbon dioxide emissions is industrial exhaust, such as cars and factories. This affects corals because their skeletons are made of calcium carbonate. When this atmospheric carbon dioxide is absorbed and mixed with seawater, it creates carbonic acid. This substance complicates the building of body parts by marine animals, such as coral. Corals' growth rate is slowed and the shells of marine snails dissolve.
-Global Warming and Coral Bleaching
Coral Bleaching occurs when the coral is stressed and expels the zooxanthellae. Without them, the coral loses its color and becomes white. Sometimes the coral will ingest new zooxanthellae, but if it does not, the coral will die. Coral thrive in water that is 66-86 degrees Fahrenheit. If the temperature changes 2 or 3 degrees outside this range, the coral will be become stressed. Currently, the oceans are rising in temperature because of global warming, an increase in the average temperature of the Earth’s atmosphere and oceans in recent decades. The warmer the water the more un-survivable the ocean for the coral is, causing coral bleaching to occur.
-White Pox Disease
A dangerous disease that is affecting the dominant Elkhorn coral is white pox. The cause is a bacterium called Serratia marcescens, a microorganism common in the human stomach. This is the first time human related bacteria have been connected to the destruction of coral, which it achieves by eating the coral's flesh, leaving the skeleton exposed. A hundred year old coral can die from white pox in a matter of weeks. A potential source of this pox could be the dumping of human waste in the ocean, which may explain why it has gone from being completely terrestrially to completely marine. Elkhorn's population is decreasing faster than it can repopulate, leading to the decline of this essential reef-building coral.
-Agriculture
Agricultural runoff can have a number of sources, including pesticides, fertilizers, herbicides, and animal feed, as well as sedimentation, which can come from land clearing, human sewage, and toxic discharges. This sewage contains phosphates, nitrogen, pathogens, and toxins. These extra nutrients are added to the ocean, leading to an explosion in the algae population. This overgrowth of algae causes the water to become murky, and makes it difficult for sunlight to penetrate the surface of the water. Coral needs clear water and access to sunlight to live, an absence of which causes a decrease in both the amount of essential, coral-building limestone available and coral population over all. Excess algae will smother coral, impacting the aquatic organisms that depend on it. Plant and animal decline is also possible.
- Other Human Induced Threats
Humans are the source of many threats to coral reefs. Tourists may break off coral by kicking it as they swim by. Some people take healthy corals or coral parts for their own aquarium. Merely touching coral can cause harm. The dropping of boat anchors, lobster traps, and fishing line and nets across reefs can break coral. Even sun tan oil can harm and possibly kill sensitive corals.