Hello everyone!

In my last post, I gave a brief overview of what the BP oil spill is and a summary of the timeline of events following the incident. I believe we all know how bad oil spills can get the oily surface of water, beaches, and birds getting caught in the oil. In this post, we will take a closer look at the impact oil spills has on animals.

#1 Physical effects
Physical contact is the major route of exposure that usually affects birds and furred mammals. Physical effects include death by suffocation due to oil obstructing air passageways or gills (Leifert, 2010). Oil can affect a creature’s ability to find food or detect predators by desensitizing sensory organs. These birds and mammals usually rely on their outer coats for buoyancy and warmth however, oil can reduce the insulating effect of feathers and fur, as they adhere to the outer layer, succumbing them to hypothermia and drowning (Saadoun, 2015). Organisms are also exposured through ingestion or inhalation of the hydrocarbon that resides on the surface. These exposure routes lead to the absorption into the bloodstream.

#2 Toxicity of oil
The general effects would depend on a multitude of factors which includes oil composition and characteristic (physical and chemical), exposure route and duration, and the bioavailability of the oil (Saadoun, 2015). One major effect of oil is narcosis, a reversible anaesthetic effect cause by the oil partitioning into the cell membrane and nervous tissue, which can cause dysfunctions of the central nervous system. If the concentration of hydrocarbons exceeds the threshold, the toxic effect can ultimately lead to mortality. When the oil are ingested, they travel to the liver where enzymes can activate polycyclic aromatic hydrocarbons (PAHs) to be even more toxic and reactive. The intermediate products produce can be highly toxic and carcinogenic. In addition, hydrocarbons are volatile in nature making it easier for inhalation which could then result in respiratory tract irritation and narcosis (Saadoun, 2015).

#3 Toxicity of oil dispersant
Oil dispersants are a common tool used as a way to clean up oil spills. Upon application, they break up the oil slick on the surface causing oil droplets to sink under the surface and increase the rate of biodegradation. They are often used when other methods like oil containment and removal are insufficient. Generally undispersed oil poses the greatest threat to shoreline and other surface dwelling creature. However, dispersed oil can remain in the water column for a long time and threaten organisms in the water column and seabed. Based on study by Ramachandran et al., 2014, it has been shown that oil dispersants increases the exposure and uptake of PAHs by fish and risk of toxicity is especially sensitive to early life stages like eggs and larvae.

#4 Indirect effects
There are other indirect effects that exist like decreased growth rates, reduced fecundity and higher mortality rates for larvae (Leifert, 2010). These effects also often go unreported. Creatures not directly affected can suffer from the lack of prey, if the latter was decimated by the oil. Take for example, zooplankton, they can assimilate hydrocarbons directly and by ingesting oil and oil contaminated food. This often result in mortality while surviving organisms often show developmental and reproductive issues (Saadoun, 2015). This is a great cause of concern as they are a primary source of food for many other organisms. 

There exists many negative impacts on animals and the environment which can have cascading effects up the food chain. In addition, we are still unsure of how long the impacts will last or if it is even possible for environment affected to recover.  

That brings me to the end of this post.

See you guys soon!

References

Leifert, H. (2010, June 14). Gulf oil spill threatens subsurface biodiversity. Retrieved November 06, 2020, from https://www.earthmagazine.org/article/gulf-oil-spill-threatens-subsurface-biodiversity

Ramachandran, S. D., Hodson, P. V., Khan, C. W., & Lee, K. (2004). Oil dispersant increases PAH uptake by fish exposed to crude oil. Ecotoxicology and Environmental Safety, 59(3), 300-308. doi:10.1016/j.ecoenv.2003.08.018

Saadoun, I. M. (2015). Impact of Oil Spills on Marine Life. Emerging Pollutants in the Environment – Current and Further Implications. doi:10.5772/60455