Hello guys! If you’re here, I assume that you read the previous article as well. Now, let’s get back to where we ended off in the last post. Are the findings, regarding foraging depths and level of plastic ingestion, from the journal article we explored previously generalizable?
Lets take a look at another journal article. This article examines plastic ingestion in 4 species of seabirds (northern Fulmars, black-legged kittiwakes, thick-billed murres and black guillemots) in the Canadian Artic, over a period of 10 years.
[Also i was pretty shocked :0 when I read that they actually shot down the birds in collaboration with Inuit hunters, for this research.. those poor birds 🙁 let’s take a moment to wish them peace. Now you better pay attention to this post. We don’t want their deaths to go to waster now do we?!]
The main finding was that “72% of fulmars and 15% of kittiwakes” had plastic ingestion while the other two species did not (Baak et al,. 2020). The table below provides the specific details about the species and the respective plastic ingestion with regards to mass and number of plastic pieces.
Furthermore, it was also investigated if sex differences in the birds affected the levels of plastic ingestion. As seen in the diagram below, it seems that there is a general trend that female fulmars have a higher level of plastic ingestion and higher average mass of plastics in them, than the male birds. Perhaps, this could be attributed to foraging habits where females have a higher frequency of foraging compared to males.
Even though this article did not mention the underlying reason for such observations, perhaps we could analyze them with regards to foraging depths to explore for an explanation. If were to categorize them according to the foraging depths like in the previous post, then fulmars and black-legged kittiwakes would be surface foraging birds while the other two species would be diving birds. That would mean that there is a negative correlation between foraging depth and level of plastic ingestion. In comparison to the key finding of the previous article, the conclusion that I have derived disagrees with it.
Overall. there are several takeaways from this article and comparing it the previous article. Firstly, this article provides a general understanding of the levels of plastic ingestion among the 4 species of birds, located specifically in the Canadian Artic. Also, it also explores that sex differences could influence levels of plastic ingestion. However, this was only explored with regards to the fulmars. Moving on, when comparing the two articles, it seems that we reach different conclusions about the correlation between foraging depth and plastic ingestion. While the previous article mentioned a larger plastic ingestion for greater foraging depth, this article implied that surface foraging is associated with greater plastic ingestion. This shows that the relationship between foraging depth and plastic ingestion for seabirds is not consistent universally. I believe that species, temporal and geographical variability influences this relationship greatly. For instance, the location of the seabirds and water body that contains plastic pollution may influence the amount of plastics ingested. Also, the level of plastic ingestion due to foraging depths across the years may differ greatly because the ocean is very dynamic. Hence, highlighting the need for sustained in-depth research for various species of seabirds across many locations as understanding the effects of plastic pollution on seabirds is very complicated. But of course, there is great difficulty in doing do due to many constraints.
References
Baak, J.E., Provencher, J.F. & Mallory, M.L. (2020) Plastic ingestion by four seabird species in the Canadian Arctic: Comparisons across species and time, Marine pollution bulletin, vol. 158, pp. 111386.
Hope you enjoyed the past few posts about seabirds 🙂