User:MRR1993/Environmental issues with coral reefs

Oil
Causes and Effects of Oil Spills

The causes for oils spills can be separated into 2 categories: natural and anthropogenic causes.

Natural causes can be from oil that leaks out from the ocean floor into the water; erosion of the seafloor; or even climate change. The amount that naturally seeps into the ocean is 181 million gallons, which varies yearly. Anthropogenic causes involve human activities and is how most oil enters the ocean. The ways oil spills anthropogenically in the ocean are because of drilling rigs, pipelines, refineries, and wars. Anthropogenic spills are more harmful than naturals spills, as unlike natural spills, they leak about 210 million gallons of petroleum each year. Also, anthropogenic spills cause abrupt changes to ecosystems with long-term effects and even longer remediations.

When oil spills occur, the affects can be felt in an area for decades and can cause massive damage to the aquatic life. For aquatic plant life an oil spill could affect how light, and oxygen is available for photosynthesis.

Two other examples of the many ways oil harms wildlife are in the form of oil toxicity and fouling. Oil toxicity affects the wildlife when the toxic compounds oil is made up of enters the body doing damage to the internal organs, and eventually causes death. Fouling is when oil harms wildlife via coating itself on an animal or plant physically.

Oil Impacts on Coral Reef Communities

Oil pollution is hazardous to living marine habitats due to its toxic constituents. Oil spills occur due to natural seepage and during activities such as transportation and handling. These spills harm the marine and coastal wildlife. When the organisms have become exposed to these oil spills, it can lead them to suffer from skin irritation, decreased immunity and gastrointestinal damage.

When oil floats above the coral reef, it will have no effect on the coral below, it is when the oil starts to sink to the ocean floor when it becomes a problem. The problem is the physical effect from the oil-sediment particle which has been found to be less harmful than if the coral came in contact with the toxic oil.

When the oil comes into contact with corals, not only the reef system will be affected but fish, crabs and many more marine invertebrates. Just a few drops of oil can cause coral reef fish to make poor decisions. Oil will impact the thinking of the coral reef fish in a way that could be dangerous to the fish and the coral reef where they choose their home.

It can negatively affect thier growth, survival, settlement behaviors, and increases predation. It has been found that larval fish who have been exposed to oil will eventually have heart issues and physical irregularities later in life.

Oil Impacts on Coral Life and Symbiotic Relationships
Evidence for the damaging effects of oil spills on coral reef structures can be seen at a reef site a few kilometers southwest of the Macondo well. Coral at this site, which has been covered in crude oil chemicals and brown flocculent particles, were found dying just seven months after the Deepwater Horizon eruption. Gorgonian octocorals (soft coral communities) are highly susceptible to damage from oil spills. This is due to the structure and function of their polyps, which are specialized in filtering tiny particles from the water.

Corals have a complex relationship with many different prokaryotic organisms, including probiotic microorganisms that protect the corals from harmful environmental pollutants. However, research has shown that oil spills damage these organisms, and weaken their ability to protect reef structures in the presence of oil pollution.

Oil Clean up Methods

Booms are floating barricades that are placed in an oil spreading area that restrict the movement of floating oil. Booms are often utilized alongside skimmers, which are sponges and oil absorbent ropes that collect oil from the water. Moreover, insitu-burning and chemical dispersion can be utilized during an oil spillage. Insitu-burning refers to burning oil that has been collected to one location with a fire-resistant containment boom, however, the combustion from insitu-burning does not fully remove the oil but instead breaks it down into different chemicals which can negatively affect marine reefs.

Chemical dispersants consist of emulsifiers and solvents that break oil into small droplets and are the most common form of oil removal, however, these can reduce corals resilience to environmental stressors. Moreover, chemical dispersants can physically harm coral species when exposed. Dispersants have been also utilized to clean oil spills, however, they harm early stages of coral and reduces the settlement on reef systems and have since been banned. However, there is still one formulation of dispersants used, the Corexit 9427. Microbial biosurfactants can be utilized to reduce the damage to reef ecosystems as an eco-friendly method, however, there are limitations to their effect. This method is still being studied and is not a certain method of oil clean up.