Marine Oil Spills

Oil spills are amongst the disasters that provoke the most intense public response – and with good reason. While oil spills can occur on land (such as in the event of a pipeline bursting), the term is usually reserved for marine oil spills. These oil spills have a devastating effect on marine ecosystems and can take anywhere from a couple of weeks to several years to clean up, depending on the volume of oil released.

When in contact, oil is absorbed into the plumage of seabirds and the fur of mammals. This reduces the insulating ability many animals rely on in colder regions, and reduces the animals’ buoyancy. Without the thick insulating coating seabirds and mammals rely on, many will suffer and eventually die from hypothermia. [1]

There are also more long-term detriments to the marine ecosystem associated with oil spills. As the oil disperses over the surface of the water, it forms a layer a few millimetres thick. This is of particular importance to zooplankton.

Many marine species, including zooplankton, rely on sunlight to find food and shelter and as the oil layer blocks it these zooplankton will perish (phytoplankton photosynthesise [9] making them directly dependent on sunlight, zooplankton feed on the phytoplankton meaning they have a secondary dependency on sunlight).

Furthermore, some zooplankton absorb hydrocarbons present in the oil by ingesting oil droplets, often leading to their death [2]. Surviving organisms also tend to display developmental and reproductive abnormalities [3]. This impacts the zooplankton population significantly, with effects that ripple up the food chain. For example, zooplankton are the primary food source for baleen whales [4].

On 25 July 2020, the Japanese owned ship “MV Wakashio” struck a protected coral reef off the coast of Mauritius while carrying 4000 tonnes of fuel oil, spilling about 1000 tonnes [5]. On 15 August 2020, the ship broke apart with the expectation of incoming stormy weather delaying any retrieval attempts [6].

The event has been described as the worst ecological disaster in Mauritius’ history, and is likely to have severe effects on the country’s tourism-dependent economy for decades [6]. Unfortunately, this is just one example of how an oil spill can impact an entire industry.

The fishing industry is directly affected by oil spills in several ways. For instance, the introduction of oil into popular fishing zones causes populations to dwindle as the fish are forced to migrate. Specifically, a 75%-85% decrease in blue crab populations was observed in the months immediately following the Deepwater Horizon Spill in 2010 [7]. This was followed by a swift recovery however, suggesting the impacts on the fishing industry directly from the oil spill are only prevalent in the short term.

The process of cleaning up an oil spill however also impacts the fishing industry. Chemicals used to break up an oil slick, known as dispersants, are commonly used and can harm marine habitats, including fish spawning and breeding grounds [8].

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References:

[1] NOAA. How does oil impact marine life? National Ocean Service Website,

https://oceanservice.noaa.gov/facts/oilimpacts.html, 03/11/20

[2] Corner EDS. ‘Pollution Studies with Marine Plankton. Part I. Petroleum Hydrocarbons and Related Compounds’. Advanced Marine Biology 1978; 15: 289-380.

[3] Jiang Z, Y Huang, X Xu, Y Liao, L Shou, J Liu, Q Chen and J Zeng. ‘Advance in the Toxic Effects of Petroleum Water Accommodated Fraction on Marine Plankton’. Acta Ecologica Sinica 2010; 30: 8-15.

[4] Yang YF, Q Wang, JF Chen and P Shi-Xun. ‘Research Advance in Estuarine Zoo‐ plankton Ecology’. Acta Ecologica Sinica 2006; 26 (2): 576–585

[5] Bearak, M., 2020. Rough Seas Are Hampering Response To Mauritius Ship Leak; Oil Spill Reaches 1,000 Tons. [online] The Washington Post. Available at: <https://www.washingtonpost.com/world/africa/mauritius-oil-spill-wakashio/2020/08/09/8dd09ee8-da49-11ea-b205-ff838e15a9a6_story.html>

[6] Mohammed, O., 2020. Japanese Ship Involved In Mauritius Oil Spill Breaks Apart. [online] News.yahoo.com. Available at: <https://news.yahoo.com/japanese-ship-involved-mauritius-oil-052541655.html?guccounter=1&guce_referrer=aHR0cHM6Ly9lbi53aWtpcGVkaWEub3JnLw&guce_referrer_sig=AQAAANUMbGfVaJwxerWG500Wk4WNZORzOiUwuQS36cqyYB9Zviw6Wd2b9af6RaCskSGTO2K2wcR7_3YK07Ah_wePaB4GHjfQ82xGzBViaQCunZWGuJT12m1xbu3zLkvcjIUOIYDrzUcc3R_bVLrDdWNc_sYypaQD0t5jVFkbmSywI1Bm>

[7] Fiore, J., Bond, C.A., Nataraj, S. and Social, R.A.N.D., 2019. The Impact of the Deepwater Horizon Spill on Commercial Blue Crab Landings. RAND.

[8] Baker, P., 2020. Oil Spill’S Impacts On Fishing Industry Varies For Inshore And Offshore Businesses. [online] EDFish. Available at: <http://blogs.edf.org/edfish/2010/05/13/oil-spill’s-impacts-on-fishing-industry-varies-for-inshore-and-offshore-businesses/#:~:text=Oil%20Spill%27s%20Impacts%20on%20Fishing%20Industry%20Varies%20for%20Inshore%20and%20Offshore%20Businesses,-«%20Offshore%20Boats%20Thriving&text=Dispersants%2C%20chemicals%20that%20break%20up,grounds%2C%20and%20other%20offshore%20habitat.>

[9] Lindsey R, Scott M. What are Phytoplankton? [Internet]. Earthobservatory.nasa.gov. 2010. Available from: https://earthobservatory.nasa.gov/features/Phytoplankton#:~:text=Like%20land%20plants%2C%20phytoplankton%20have,energy%20by%20consuming%20other%20organisms.