When someone mentions the Bering Sea, the first thought that would probably come to mind is tumultuous seas and Alaskan King crab. In today’s blog post, we will be talking about the Bering Sea, and how climate change is having an affect on the creatures that inhabit these cold northern waters. For those who may not be familiar the Bering Sea it is a body of water that connects the Subarctic North Pacific Ocean with the Arctic Ocean. This blog will focus mainly on the eastern half of the Bering Sea. This part of the Bering Sea is a broad shelf that stretches a span of over 1100 km northward from the Alaskan Peninsula. This section of the Bering Sea has an extremely productive ecosystem that is supportive of large quantities of seabirds and marine mammals, subsistence harvests for native Alaskan communities, and greater than 40 percent of the U. S. catch of fish and shellfish. Sea ice is a crucial factor in sustain the ecosystem in this area. The graph below shows how ice coverage has decreased over the Bering Sea in recent decades.
The graph above shows the median max/min sea ice coverage on the Bering Sea between 1979-2016 2016 and compares it with the sea ice overage during 2017-2018. https://arctic.noaa.gov/Report-Card/Report-Card-2018/ArtMID/7878/ArticleID/780/Sea-Ice
During the winter of 2018 and 2019, the maximum sea ice coverage in the Bering Sea was at an all–time low, obtaining less than half of the previous long – term mean (1980 2010). In 2018, there was a distinct northward shift in the walleye pollock and Pacific cod over the Bering Sea shelf. Normally these species are found on the southern shelf and/or on the outer shelf, where water temperatures are typically greater than 2 degrees Celcius. In 2019, large numbers of walleye pollock and Pacific cod were once again found in the Northern Bering Sea. The change in distribution was likely a result of the cold pool, the location at the bottom of the shelf where temperatures are less than 2 degrees Celcius. During 2018, the cold pool was nearly non-existent and in 2019 the cold pool was slightly more noticeable, but still less prominent than normal. (Recent warming in the Bering Sea and its Impact on the Ecosystem) arctic.noaa.gov. The facts just mentioned were likely the cause for the northward shift in these species.
https://www.youtube.com/embed/bMcQnSeZF74?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en&autohide=2&wmode=transparentCCTV. https://www.youtube.com/watch?v=bMcQnSeZF74. YouTube. (Video). Retrieved February 22, 2022.
Now that we have discussed a couple of underwater species, we will now talk about sea birds. According to the Fish and Wildlife Service, there were seabird die-offs that occurred on the Bering Sea shelf during 2018 and 2019. The largest die-offs occurred over the southern shelf, which affected short-tailed shearwaters. These waters washed ashore on Bristol Bay during July and August. While the exact cause of the die-off is unknown, it is likely to warmer ocean waters. Some other potential causes may include: the northward shift in walleye pollock and Pacific cod competing for shearwaters for food in the northern Bering Sea; increased toxins from algae bloom; or possibly other causes that are still unknown. The following graph from the National Wildlife Service shows a 2018 report card for a number of sea birds species.
The lack of ice extent during 2018 and 2019 was likely caused by three factors. The first and most highly contributing cause was the unusually warm, southerly winds that were present during the winter. This factor limited the amount of sea ice extent, or at least caused the sea ice to retreat significantly during the winter months. The second reason was the late freezing of the Chuckchi Sea during the winter of 2017 and 2018, causing a late arrival of the ice cover on the northern Bering Sea. Lastly, warm ocean waters helped to slow the advancement of sea ice (Wood).
it is important to note that some species of fish migrate naturally, based on changes in the seasonal temperature. During the summer months, they tend to move northward into colder, deeper waters, and then return southward in the winter. As a result of climate change, the sea temperatures are becoming warmer at all points throughout the year. This may cause certain species to move northward away from warm water and into a location where the water is still relatively cool (www.epa.gov).
Fish production in the Bering Sea can be affected not only by the environment, but also by food webs, One of the ways that climate change can alter fish production is because temperatures can have a direct affect on metabolism, causing growth and distribution of a species. Food web effects may also result from changes in the distribution and quantity of prey or predators (www.beringclimate.noaa.gov)
Another impact that climate change is having in the Bering Sea is an increased number of animal die-offs. This problem does not just affect the species that are dying, but it is also having a negative impact on the species that rely on them as a food source. The Northern Bering Sea, Chuckchi, and Beaufort Seas have experienced die-offs, displacement, and disappearance of some fish species and ocean invertebrates. The ecosystem of this area is also important to seals, walruses, bears, migratory gray whales, birds, sea lions, and a number of other creatures. A loss of ice cover along with long stretches of record-breaking ocean heat have changed this ecosystem from bottom to top and from top to bottom according to those who study the creatures that live in it. Not only are zooplankton and algae affected, but the change in the ecosystem has also caused predators like the killer whale to move to areas that were once locked by ice. The presence of such a predator can have a detrimental affect on other species in these locations (Rust).
Climate Change Indicators: Marine Species Distribution | US EPA. www.epa.gov. Feb. 3, 2022. Web.
Patricia A. Livingston, Wilderbeur K. Thomas. What is the Impact of the Ecosystem on Fishery Resources in the Bering Sea? NOAA Fisheries – Alaska – Fisheries Science Center Seattle, WA. www.beringclimate.noaa.gov. Feb. 3, 2022. Web.
Rust, Susanne. Climate change transforms ecosystems in the Arctic and beyond. Unprecedented die-offs, melting ice: Climate change is wreaking havoc in the Arctic and beyond. www.latimes.com Dec. 17, 2021. Web. Feb.16, 2022.
Wood, K. et al. Arctic Program. Recent Warming in the Bering Sea and its Impact on the Ecosystem. www.arctic.noaa.gov. Dec. 6, 2019. Web. Feb. 3, 2019.
National Park Service. Alaska Nature and Science. https://www.nps.gov/subjects/aknatureandscience/seabird2018.htm. Image. Web. Retrieved February 22, 2022.
Arctic Program. Arctic Report Card: Update for 2018. Image. https://arctic.noaa.gov/Report-Card/Report-Card-2018/ArtMID/7878/ArticleID/780/Sea-Ice. Web. Retrieved February 22, 2022.