Abstract
We describe a fecundity-hindcast model that incorporates Arctic cod (Boreogadus saida) acute toxicity data, field studies of Arctic cod larval distribution and abundance, natural mortality estimates for Arctic cod eggs and larvae, and an oil spill fate model in Alaska Beaufort Sea. Three orders of magnitude of spill events (1000, 10 000, and 100 000 tons) were evaluated for both physically and chemically dispersed oil. Using worst-case assumptions in our model, a 100 000 ton spill of crude oil treated with dispersants resulted in 266 million m3 of water that exceeded our acute toxicity threshold, compared to a volume of 71 million m3 for a 100 000 ton spill not treated with dispersants, and resulted in exposure of about 2 million Arctic cod larvae remaining from an initial 87 million eggs. This represents the reproductive output of about 7300 adult females. Adult Arctic cod populations in the Alaska Beaufort number in the tens to hundreds of millions. The results show that even with an order of magnitude variation in exposure, the effect of dispersing a large oil spill on the regional cod population is expected to be insignificant (∼0.7%). The recent hiatus in Arctic oil and gas development affords an opportunity to acquire additional data to further strengthen this conclusion.
Highlights
Prior to 2015, the high price of oil resulted in an increase in exploration for oil and gas in the Beaufort and Chukchi seas of northern Alaska
Instead of assuming only half the larvae were removed from the water volume, we assumed 100% were removed, and we assumed that they were removed even if they were exposed for only one model time step (1 h) even though the thresholds were based on exposing Arctic cod larvae to PAH for 96 h
In total, 545 larval and juvenile fish were identified to species or the lowest taxonomic level possible from the samples collected in the Beaufort Sea during the ice-free season of 2011
Summary
Prior to 2015, the high price of oil resulted in an increase in exploration for oil and gas in the Beaufort and Chukchi seas of northern Alaska. Dispersants reduce the surface tension of oil to allow formation of small droplets after a surface slick is subjected to wave energy or a subsea jet of oil is released into the water with high energy This results in small droplets that are entrained in the water column and subjected to microbial biodegradation. The panel concluded that data on the relative toxicity of crude oil and dispersed oil to pelagic and epipelagic organisms in the Arctic were limited and that additional toxicity data based on Arctic organisms tested under Arctic conditions were needed. This led to a toxicity research program as reported by Gardiner et al (2013). The ice-free season is relevant because it is when exploratory drilling will occur in the Arctic
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
