One of the greatest marine oil spills 

The Deepwater Horizon oil spill (BP oil spill) began on 20 April 2010 in the Gulf of Mexico after an explosion of the Deepwater Horizon oil rig (Pallardy, 2020). It is commonly regarded as one of the greatest environmental disasters in history, with an estimated spillage of 4.9 billion barrels of oil (Shawke, 2013), and 60,000 barrels escaping from the well per day (Pallardy, 2020). The disaster was extremely devastating – it caused (and still is casuing) extensive ecosystem-level injury to all organisms and affected more than 2100km of shoreline (Beyer et al., 2016). Fully understanding the impacts of the oil spill is complex, and till today, the full extent is still unknown. We only have space to illustrate a select few impacts, but note that the repercussions of the oil spill far transcend these!

Corals 

Since corals have great longevity, damaged colonies may signify irreversible damage to these important ecosystems. Corals have experienced varying degrees of damage to the oil spill, such as some corals covered with floc-containing oil dying off (Beyer et al., 2016). A study by White el al. (2012) revealed that corals situated 11km of the southwest Macondo well demonstrated widespread stress from the disaster such as excessive mucus production, tissue loss and retracted polyps. For instance, 86% of coral colonies in the central area of the study site exhibited signs of stress (e.g. brown flocculent material, heavy mucus, bare skeleton above the base) with 46% exhibiting impact to more than half the colony. Till today, corals are experiencing branch loss and those injured have been colonised by opportunistic hydroids (Beyer et al., 2016). 

Though the impacts on coral colonies have not been entirely devastating, it is arguably still too early to fully understand the long-term effects of contaminants since corals function at a slow pace (White et al., 2012) which would take time for the effects to appear. 

Coastal habitats – Salt marshes 

Stranded oil on coastlines is worrying, since only a relatively small amount of oil is required to detriment coastal ecosystems. Louisiana’s salt marshes for instance, is already facing the brunt of intense human activities and has some of the highest salt marsh losses in North America of about 75 km2/y (Silliman et al., 2012). The oil spill only served to accelerate the pace of salt marsh degradation – of about twice compared to un-affected areas (Silliman et al., 2012). 

This is attributed to the oil degenerating the stabilising root matrix which helps to maintain the shoreline structure and guard against erosion by holding together sediments (Silliman et al., 2012). The intrusion of oil degrades the microbial community in sediments, where plants suffered as the bottom layer of soil was progressively weakened (Beyer et al., 2016). This has serious repercussions on the salt marsh ecosystem for the many organisms which depend on it for survival, since oil spills have been shown to present long-lasting effects on animal behaviour and the food web (due to the persistence of oil-derived compounds) (Silliman et al., 2012). 

Animals 

The environmental cost to animals such as birds, turtles, dolphins, fishes, crabs, are massive and horrifying. It is inconceivable. I was shocked by how severely affected these animals were simply because of our actions. Of the lot, birds were the most vulnerable – some 800,000 birds have died from the BP oil spill (Pallardy, 2020). They have been affected via a myriad of ways directly and indirectly – such as habitat destruction like salt marshes (Beyer et al., 2016), the accidental ingestion of oil while preening and the hampered ability to regulate their body temperature because of the oil (Pallardy, 2020). It is estimated that during the 2010 to 2011 non-breeding season, more than one million migratory shorebirds were exposed to the oil spillage (Beyer et al., 2016).

In a study by Shwake at al. (2013), the dolphins examined in Barataria Bay in Louisiana had abnormally low levels of adrenal hormones which indicated hypoadrenocorticism. It is a condition which could possibly hamper critical physiological processes (e.g. metabolism and cardiovascular function) and other potentially fatal complications. In a similar vein, an estimated 65,000 turtles had died in 2010 alone. The BP disaster is a reminder of the global and transboundary nature of environmental pollution. Some of 300,000 turtles from breeding populations originating from other regions were found where the spill occurred (Pallardy, 2020).

Before we end this post, do take a look at the video below, and maybe reflect a little? 🙂 It highlights the persistent long-term repercussions of the BP oil spill on animals, and the on-going efforts by committed parties to remedy this disaster. 

 

References:

Beyer, J., Trannum, H.C., Bakke, T., Hodson, P.V. & Collier, T.K. (2016) Environmental effects of the Deepwater Horizon oil spill: A review. Marine Pollution Bulletin. 110(1), 28-51. Available from: http://dx.doi.org/10.1016/j.marpolbul.2016.06.027. 

Pallardy, R. (2020) Deepwater Horizon oil spill. Available from: https://www.britannica.com/event/Deepwater-Horizon-oil-spill/Cleanup-efforts [Accessed 15 September 2020]. 

Schwacke, L.H., Smith, C.R., Townsend, F.I., Wells, R.S., Hart, L.B., Balmer, B.C., Collier, T.K., De Guise, S., Fry, M.M., Guillette, L.J., Lamb, S.V., Lane, S.M., McFee, W.E., Place, N.J., Tumlin, M.C., Ylitalo, G.M., Zolman, E.S. & Rowles, T.K. (2013) Health of common bottlenose dolphins (tursiops truncatus) in Barataria Bay, Louisiana, following the Deepwater Horizon oil spill. Environmental Science & Technology. 48(1), 93-103. Available from: dx.doi.org/10.1021/es403610. 

Silliman, B.R., Johan van de Koppel, McCoy, M.W., Diller, J., Kasozi, G.N., Earl, K., Adams, P.N. & Zimmerman, A.R. (2012) Degradation and resilience in Louisiana salt marshes after the BP-Deepwater Horizon oil spill. Proceedings of the National Academy of Sciences – PNAS. 109(28), 11234-11239. Available from: https://doi.org/10.1073/pnas.1204922109. 

White, H.K., Hsing, P., Cho, W., Shank, T.M., Cordes, E.E., Quattrini, A.M., Nelson, R.K., Camilli, R., Amanda W.J. Demopoulos, German, C.R., Brooks, J.M., Roberts, H.H., Shedd, W., Reddy, C.M. & Fisher, C.R. (2012) Impact of the Deepwater Horizon oil spill in a deep-water coral community in the Gulf of Mexico. Proceedings of the National Academy of Sciences – PNAS. 109(50), 20303-20308. Available from: http://www.pnas.org/cgi/doi/10.1073/pnas.1118029109 

 

Images: 

Office of Response and Restoration (2016) How do oil spills affect sea turtles? Available from: https://response.restoration.noaa.gov/about/media/how-do-oil-spills-affect-sea-turtles.html [Accessed 15 September 2020]. 

Scientific Earth Conscientious (2012) BP Deepwater Horizon oil spill exacerbated existing environmental problems in Louisiana marshes. Available from: https://scientificearthconscientious6.wordpress.com/2012/06/25/557bp-deepwater-horizon-oil-spill-exacerbated-existing-environmental-problems-in-louisiana-marshes/ [Accessed 15 September 2020].