Hello everyone!

As occurrences of wildfires are happening more frequently, how much do the smoke and chemical released in the process affect marine mammal? It might seem like there is no link between the fires on land and the species in the water but there is more to this than meets the eye. 

Wildfire smoke is made up of a variety of gases which include carbon monoxide, nitrogen dioxide, polycyclic aromatic hydrocarbons (PAHs), and particulate matter. It has been shown to increase the risks of respiratory and cardiovascular illnesses in humans (Wettstein et al., 2018). Marine mammals like whales, dolphins, porpoises are adapted to life at sea with lesser air pollutants. They are expected to be more vulnerable to injury from inhaled particulates (Basu, 2020). This could lead to grave consequences especially for species that are already endangered. 

So what makes them more vulnerable to the harmful effect of smoke?
The main reason is their anatomy. They exchange big gulps of air rapidly through their blowholes which makes it easier for them to inhale the airborne smoke particles. They also lack sinuses and other nasal structures that provide a physical barrier to trap the particles in mucus which will be sneezed or coughed out (Basu, 2020). As such, more particles are able to enter their lungs much more easily. From necropsies of 46 dead dolphins that washed ashore following the BP oil spill, they suffered severe lung disease and deteriorated adrenal glands, organs that regulate hormones, and more. Scientists concluded that this could have been caused by the exposure to hydrocarbons in the smoke (Basu, 2020). This could lead to impacts on reproductive systems and cancer.
In addition, mammals that tend to stay closer to shore and breathe more frequently, like dolphins and porpoises, are more likely to experience irritation of their airways and absorb more hydrocarbons as compared to deep-diving mammals like whales.
A study was done by Bowen et al. in 2014, where they study 39 California sea otters that were exposed to wildfire smoke and runoff, a toxic mix of metal, chemicals and, sediments that flowed into the water bodies adjacent to the forest fires. It was found that their immune systems were weakened as a result. The number of animals in the study was small and the long-term impacts on the species still remain unknown.

More research needs to be done to better understand the effect of wildfire smoke on marine mammals. Conducting such research is difficult as it is impossible to study the animals while a wildfire is raging. A long-term project is needed to study the effects as they are usually cumulative, therefore, following the animals for decades is key especially for species that are long-lived.

That brings me to the end of this post.

See you guys soon!

References

Basu, B. (2020, September 30). Wildfire smoke may harm whales and dolphins: Here’s what we know. Retrieved November 01, 2020, from https://www.nationalgeographic.com/animals/2020/09/whales-dolphins-harmed-wildfires-smoke-west/

Bowen, L., Miles, A. K., Kolden, C. A., Saarinen, J. A., Bodkin, J. L., Murray, M. J., & Tinker, M. T. (2014). Effects of wildfire on sea otter (Enhydra lutris) gene transcript profiles. Marine Mammal Science, 31(1), 191-210. doi:10.1111/mms.12151

Wettstein, Z. S., Hoshiko, S., Fahimi, J., Harrison, R. J., Cascio, W. E., & Rappold, A. G. (2018). Cardiovascular and Cerebrovascular Emergency Department Visits Associated With Wildfire Smoke Exposure in California in 2015. Journal of the American Heart Association, 7(8). doi:10.1161/jaha.117.007492