"Toxic algae blooms increasing in the Arctic due to climate change, new study finds"
By: Shyleigh Good
Peer-Reviewed Journal Article Link
Background
Toxic algae cells are commonly found at low, benign
concentrations in a variety of surface waters.1 When cells are subject
to favorable environmental conditions (e.g. high nutrient availability, warm
temperatures, etc.) for reproduction, they rapidly increase in concentration, forming
harmful algal blooms (HABs).1–6 These
proliferation events result in a greater abundance of toxins produced by the
cells. Algal toxins harm humans and wildlife, as they can bioaccumulate in food
chains to induce illnesses in consumers and can be aerosolized to cause respiratory
issues.1 Accounts of illnesses
and mortality experienced by coastal communities who consume marine wildlife have
been occasionally reported for over 200 years, indicating that HABs occur in
natural fluxes.2 Recently, HABs
have increased in frequency and spread to cooler locations typically not affected
by them due to anthropogenic activities, which are changing environmental
conditions to be more favorable for toxic algae cell reproduction.2
Fig. 1. Chukchi Shelf and Western Beaufort cyst beds are located in areas of high cyst accumulation.4
Like A. cantenella, Psedo-nitzschia species can be transported to the Alaskan Arctic by currents. They are also natively found in sea ice.9 During unfavorable environmental conditions for HABs, these cells exist at low concentrations, but they rapidly reproduce when conditions become favorable.3
As temperatures rise in the Arctic,10 environmental conditions are becoming more favorable for A. catenella and Psedo-nitzchia species to form HABs. A. catenella and Psedo-nitzchia species produce saxitoxin (STX) and domoic acid (DA), respectively, which are harmful neurotoxins that can cause paralytic shellfish poisoning and amnesic shellfish poisoning in humans and domoic acid poisoning in marine wildlife.1,9 These neurotoxins are of utmost concern to Indigenous communities, whose diet heavily consists of marine wildlife.3 The selected study discusses changes in STX and DA concentrations in bowhead whale feces as a result of Arctic warming from 2004 to 2022.
Peer-Reviewed Journal Article
Rising temperatures in the Alaskan Arctic are accelerating harmful algal blooms (HABs) in the Beaufort Sea, threatening Indigenous communities and marine wildlife. The most abundant types of algae in the Alaskan Arctic are Alexandrium catenella and Pseudo-nitzschia species, which arise from local and regional sources. A. catenella and Pseudo-nitzchia species produce neurotoxins, namely saxitoxin (STX) and domoic acid (DA), respectively, that accumulate in marine food chains. STX and DA concentrations in marine wildlife can provide insights into the frequency and danger of HABs.
This study quantified STX and DA concentrations in the feces of bowhead whales harvested in Utqiagvik, Alaska, from 2004 to
2022. Feces from 205 bowhead whales were analyzed by ELISA
bioassays. Fecal STX and DA concentrations were compared to water temperature,
wind, and sea ice data to determine environmental influences on HABs.
To determine how the transport of warmer water from Barrow
Canyon impacts toxin production at the bowhead whale feeding site, heat fluxes were
calculated daily from the collection date to 20 days prior collection of every sample. Fig. 2a
and Fig. 2b show that DA and STX concentrations, respectively, and heat fluxes are directly related, but the days prior collection for when this relationship is evident differs between them. DA concentrations and heat fluxes are directly related 20 days prior collection because warm water from Barrow Canyon not only increases the temperature of the feeding site but also transports vegetative cells, which are the primary source of DA, that forms HABs, increasing DA concentration. On the other hand, STX
concentration and heat fluxes are directly related 10 days prior collection because cyst germination, initiated by the warm Barrow Canyon water, took 10 days to complete and produce vegetative cells. Heat flux, and thus also STX and DA concentrations, decreased when northeasterly winds slowed the Alaskan Coastal Current.
Fig. 2. Major currents in the Chukchi and Beaufort Seas (a). Heat fluxes, in relation to DA (b) and STX (c) concentrations, calculated 20 days prior to collection of bowhead whale feces.4
In addition to heat flux, sea ice influences STX and
DA concentrations. As the Alaskan Arctic warms, sea ice is declining, resulting
in open water that warms more quickly. More open water was associated
with higher STX and DA concentrations.
The Alaskan Arctic environment is changing due to increased
temperatures. Water temperatures are becoming warmer while sea ice is melting.
This study focuses on the issue that warming environmental conditions are catalyzing HABs, resulting in increased toxin concentrations in Arctic food chains. Many HABs species that were once quiescence
in the Arctic are now becoming active. The Chukchi and Western Beaufort cyst beds
pose major threats as the Arctic warms.
Online News Article
Julia Jacabo’s “Toxic algae blooms increasing in the
Arctic due to climate change, new study finds” published by the ABC news agency
provides an overview of the study, highlighting why HABs are currently of concern in the Arctic. The beginning of the article immediately states the major conclusion of
the study. Descriptions of the lead author and collaborators follow as well as a
more thorough description of why HABs are more prevalent in the Arctic and how
they are impacting Indigenous communities and wildlife. The article focuses
more on A. cantenella, even describing the formation of cyst beds and
why cyst beds pose threats as the Arctic warms. Jacobo interviewed the study’s
lead author, Kathi A. Lefebvre, who provided additional explanations of the
study. A brief statement about similar HABs in California was included at the end of the
article.
Review
While the science of the article is accurate and agrees with the peer-reviewed journal article, content not related to the study was included. The written part of
the article focuses on HABs in the Alaskan Arctic, like the study, but the short
news clip, while having a thumbnail picture of bowhead whales in the Beaufort
Sea, talks about HABs on the West Coast of California. Likewise, the scanning
electron microscopy (SEM) image, although of relevant algal cells, is not in
the study. Additionally, important content from the study, including Pseudo-nitzchia
species and large cyst beds that of major concern, are not mentioned. Overall,
the article is lengthy. I think that the broader impacts of the study should have
been included in one of the first paragraphs instead of near the middle of the
article. The misleading and omitted content and the ineffective arrangement of
the article led me to rate it as 6/10.
References
1. Van Dolah, F. M. Marine Algal Toxins: Origins, Health Effects, and Their Increased Occurrence. Environ. Health Perspect. 2000, 108 (suppl 1), 133–141. https://doi.org/10.1289/ehp.00108s1133.
2. Anderson, D. M.; Fachon, E.; Pickart, R.
S.; Lin, P.; Fischer, A. D.; Richlen, M. L.; Uva, V.; Brosnahan, M. L.;
McRaven, L.; Bahr, F.; Lefebvre, K.; Grebmeier, J. M.; Danielson, S. L.; Lyu,
Y.; Fukai, Y. Evidence for Massive and Recurrent Toxic Blooms of Alexandrium
Catenella in the Alaskan Arctic. Proc. Natl. Acad. Sci. 2021,
118 (41), e2107387118. https://doi.org/10.1073/pnas.2107387118.
3. Woods Hole Oceanographic Institution;
Anderson, D.; Fachon, E.; Hubbard, K.; Lefebvre, K.; Lin, P.; Pickart, R.;
Richlen, M.; Sheffield, G.; Van Hemert, C. Harmful Algal Blooms in the Alaskan
Arctic: An Emerging Threat as the Ocean Warms. Oceanography 2022.
https://doi.org/10.5670/oceanog.2022.121.
4. Lefebvre, K. A.; Charapata, P.;
Stimmelmayr, R.; Lin, P.; Pickart, R. S.; Hubbard, K. A.; Bill, B. D.;
Sheffield, G.; Bowers, E. K.; Anderson, D. M.; Fachon, E.; Thoman, R. Bowhead
Whale Faeces Link Increasing Algal Toxins in the Arctic to Ocean Warming. Nature
2025, 644 (8077), 693–698.
https://doi.org/10.1038/s41586-025-09230-5.
5. Fischer, A. D.; Brosnahan, M. L. Growing
Degree-Day Measurement of Cyst Germination Rates in the Toxic Dinoflagellate
Alexandrium Catenella. Appl. Environ. Microbiol. 2022, 88
(12), e02518-21. https://doi.org/10.1128/aem.02518-21.
6. Brosnahan, M. L.; Ralston, D. K.;
Fischer, A. D.; Solow, A. R.; Anderson, D. M. Bloom Termination of the Toxic
Dinoflagellate Alexandrium Catenella : Vertical Migration Behavior,
Sediment Infiltration, and Benthic Cyst Yield. Limnol. Oceanogr. 2017,
62 (6), 2829–2849. https://doi.org/10.1002/lno.10664.
7. Anderson, D. M.; Fensin, E.; Gobler, C.
J.; Hoeglund, A. E.; Hubbard, K. A.; Kulis, D. M.; Landsberg, J. H.; Lefebvre,
K. A.; Provoost, P.; Richlen, M. L.; Smith, J. L.; Solow, A. R.; Trainer, V. L.
Marine Harmful Algal Blooms (HABs) in the United States: History, Current
Status and Future Trends. Harmful Algae 2021, 102, 101975.
https://doi.org/10.1016/j.hal.2021.101975.
8. Azanza, R. V.; Brosnahan, M. L.;
Anderson, D. M.; Hense, I.; Montresor, M. The Role of Life Cycle
Characteristics in Harmful Algal Bloom Dynamics.
9. Hubbard, K. A.; Villac, M. C.; Chadwick,
C.; DeSmidt, A. A.; Flewelling, L.; Granholm, A.; Joseph, M.; Wood, T.; Fachon,
E.; Brosnahan, M. L.; Richlen, M.; Pathare, M.; Stockwell, D.; Lin, P.;
Bouchard, J. N.; Pickart, R.; Anderson, D. M. Spatiotemporal Transitions in
Pseudo-Nitzschia Species Assemblages and Domoic Acid along the Alaska Coast. PLOS
ONE 2023, 18 (3), e0282794.
https://doi.org/10.1371/journal.pone.0282794.
10. Rantanen, M.; Karpechko, A. Yu.; Lipponen, A.; Nordling, K.; Hyvärinen, O.; Ruosteenoja, K.; Vihma, T.; Laaksonen, A. The Arctic Has Warmed Nearly Four Times Faster than the Globe since 1979. Commun. Earth Environ. 2022, 3 (1), 168. https://doi.org/10.1038/s43247-022-00498-3.
Hi Shyleigh. Great analysis of both news article and peer-reviewed study. I think the background of your post does a nice job setting the reader up for the study you dive into. I also like how you summarized the results of the study nicely and included some ket images which helps with understanding. You stated some effects that these HAb's would have on local marine wildlife, but could the neurotoxins that are increasing in the region be harmful to humans as well, and did the article mention anything about human health effects? Also, I am curious about the future goal of the research. Did the authors mention any timeline when these HAB's would get to a point where regulations might need to be put in place, or offer any sort of short/long term solution? Great work!
ReplyDeleteHi Cody! Thank you! Yes, the neurotoxins are harmful to humans. The article mentions amnesic shellfish poisoning (ASP) and paralytic shellfish poisoning (PSP) from DA and STX, respectively. Van Dolah (2000) goes into more depth about both poisonings, elaborating on their neurological effects. According to Van Dolah (2000), PSP seems to be more lethal and common than ASP because PSP globally results in approximately 2000 human poisonings every year, while ASP has not been reported since 1987. As for future research, Lefebvre et al. (2025) suggest continuing to quantify DA and STX in marine wildlife to evaluate HABs. The authors do not propose timelines, solutions, or regulations for HABs in the Arctic. They do, however, raise awareness about the potential of harm that HABs could cause to Indigenous communities as the Arctic continues to rapidly warm.
DeleteHi Shyleigh, great analysis and thank you for sharing this study! I know the authors focused on HABs in seawater, but is there any mention of HABs in freshwater in that region, and how that may impact the health and food supply of communities in northern Alaska? If not, do you have any thoughts, based on what you read, if this is or will become an issue as well? Also, do the authors discuss any ways to take action (such as regulations)?
ReplyDeleteThis comment has been removed by the author.
DeleteHi Sophie! Thank you! Lefebvre et al. (2025) does not mention anything about HABs in Arctic freshwater. I think that HABs could occur in Arctic freshwater if the environmental conditions are favorable for the reproduction of A. catenella and/or Pseudo-nitzschia species. Since the Arctic is primarily isolated, I think freshwater HABs are less likely to occur as compared to HABs in the ocean. Most studies focus on HABs in the ocean due to the large Chukchi Shelf and Western Beaufort cyst beds that pose significant threats. Anderson et al. (2021) mentions that HABs in the ocean significantly impact the supply of food, harming food security and the economy. Lefebvre et al. (2025) do not mention any regulations. However, after a quick Google search, I found The Harmful Algal Blooms and Hypoxia Research and Control Amendments Acts (https://www.epa.gov/habs/harmful-algal-bloom-and-hypoxia-research-and-control-amendments-act-habhrca) that highlights the importance of research for monitoring HABs. I think that creating regulations to limit HABs would be difficult due to the numerous sources that influence their formation and the ubiquitous nature of cysts and cells.
DeleteHi Shyleigh, great analysis and choice of news article and peer-reviewed study. I found the background you included very helpful and providing great context. After learning about the effects of seasonality with water temperature and about wind patterns on water movement in class, I am also curious to learn more about how these aspects played into how the researchers conducted their study and if there were any findings they noted in this paper, especially any correlations between measured toxins with time of year.
ReplyDeleteHi Helen! Thank you! The fecal samples were collected from August to October, as this is the harvest season for them, and DA and STX concentrations were compared to open water and water temperature from June to September. Lefebvre et al. (2025) found that higher DA and STX concentrations were directly related to open water in June and water temperatures in July. They did not specify a specific month when toxins would be greater than other times of the year. Generally, if the Arctic is warmer from June to September, there will be more open water, which warms the oceans, forms more HABs, and increases toxins for that year.
DeleteHi! Great analysis! I had no idea that cold weather suppressed algae reproduction or that algae blooms and A. catenella produced neurotoxins. Were there limitations to the study? Also are there methods to mitigate the effects of the neurotoxins on human health besides limiting the intake of the marine life?
ReplyDeleteHi Ava! Thank you! I think the major limitation of this study is that only two of the many toxins in the fecal samples are presented. In addition to STX, A. catenella produces three other neurotoxins that cannot be quantified by ELISA bioassay kits. Lefebvre et al. (2025) and other studies do not mention how to mitigate neurotoxins other than reducing the consumption of marine wildlife. Van Dolah (2000) mentions that paralytic shellfish poisoning from STX is due to the inhibition of a sodium channel in the brain while amnesic shellfish poisoning from DA is due to the production of too much calcium. So potential treatments could include anything that unblocks the sodium channel or removes excess calcium. The effects of STX might not be treatable, as 15% of cases result in mortality, according to Van Dolah (2000).
DeleteHi Shyleigh, great analysis! Thanks for laying out such a detailed background on HABs in the Alaskan Arctic; this really helped me follow the study’s context. I’m curious: (1) Why were bowhead whale feces chosen as the monitoring matrix over tissues or prey species? (2)About the California part in the news: California is already warm. So are those HAB events mainly caused by global warming, or by other factors like marine heatwaves, unusual upwelling, extra nutrients from land?
ReplyDeleteHi Siyu! Thank you! 1) The authors do not directly explain why they used feces samples. Since Lefebvre et al. (2025) collaborated with other research groups who collected tissue samples for this campaign, I think that they collected fecal samples to gain a better understanding of DA and STX in bowhead whales. Additionally, the collection of feces samples is non-intrusive, preserving the whale for harvest by coastal communities, and provides insights into the bioaccumulation of toxins in the food chain. 2) The studies and news article do not explain whey HABs are increasing in California, but I think a combination of all of those factors are increasing the frequency and severity of HABs. After a quick Google search, I learned that wildfires may also be increasing HABs. The ash and residue from wildfires increases the nutrient load of runoff into the ocean, making environmental conditions more favorable for HABs (https://opc.ca.gov/2025/02/from-ashes-to-action-wildfire-impacts-on-californias-coast-and-ocean-health/).
DeleteHi Shyleigh. Great analysis and choice of articles. How does the warming of Arctic waters and the melting of sea ice lead to the growth of more toxic algae, and how does this increase the amount of harmful toxins found in marine animals like bowhead whales?
ReplyDeleteGreat Job, reading these articles I was very surprised to learn that ocean temperatures in the seas surrounding Alaska have increased enough to support HABs. Its unfortunate that communities, such as those living in northern Alaska are effected by a problem which they had no role in causing. It was mentioned that there are tests or methods of detection for the two illnesses caused by HABs, ASP and PSP, in tropical regions that are accustomed to HABs. It was then said that these tests would be difficult to conduct in the remote regions of Alaska. I was wondering if you had any information as to why these tests would be difficult to implement in Alaska? The news article published did a good job highlighting the important findings of the research paper, but I agree that the inclusion of California HABs seemed a bit unrelated, especially since California would definitely have the infrastructure to test and prevent ASP and PSP by testing for the harmful toxins.
ReplyDeleteMy favorite part about this study is the collaboration with indigenous communities. I believe indigenous people possess a wealth of knowledge that complements Western science. Therefore, collaborating with indigenous people increases the knowledge available to aid researchers in their studies.
ReplyDeleteIn terms of the news article, I understand your point that the news article included too much information that was not in the peer-reviewed journal article. However, in my opinion, it is more important that the news article successfully conveys the science in an easy-to-understand manner, which it does. I think including the SEM image is powerful for the reader to visualize what is being discussed, and it acts as an attention grabber. Additionally, the news article was well-balanced in terms of detailed scientific explanations versus simpler ones. I appreciated how the authors used the scientific name for the type of bacteria and provided a simpler explanation of its significance. One drawback of the news article I noticed is that the authors did not include a call to action to advocate for measures to mitigate the impacts of climate change, as it is driving these Arctic algal blooms.
Nice work, Shyleigh! I really liked how you explained how increasing HABs in the Arctic are connected to rising temperatures and cyst formation. Your summary of the study made it easy to understand how heat flux and sea ice changes affect toxin levels. I also agree that the news article could’ve been better organized and more focused on the actual study.
ReplyDeleteHow do you think changes in ocean currents might influence the spread or intensity of future HAB events in the Arctic?
Hi Shyleigh, great job! I have quite a few wishes for the author after reading the article as it left we feeling like I need more information. My main confusion was why bowhead whales were chosen. I also wanted more information on the wind speeds so that I could compare it to what is known in literature about sea spray aerosols.
ReplyDeleteI'm curious if the news article mentioned California based on the one cited paper that discussed HABs in California as maybe it was a way to draw in a larger audience.
Hi Shyleigh! Thank you for presenting and finding such an interesting article.
ReplyDeleteGiven the observed warming of Arctic waters, is it possible to extrapolate historical temperature trends to predict future conditions, and from there, estimate how rapidly A. catenella and Pseudo-nitzschia populations might increase and produce harmful neurotoxins such as saxitoxin and domoic acid? Furthermore, can projected toxin concentrations be linked to potential impacts on local wildlife, including marine mammals and fish, as well as on water quality and human communities that rely on these resources for subsistence? Essentially, can rising temperatures be used to model both the likelihood of harmful algal blooms and the severity of their ecological and public health consequences?
Hey shyleigh! I think you did a good job summarizing the article. I particularly like how you criticized the news article and compared it to the peer reviewed article. One thing I am curious about is which specific species are most affected by the algae blooms. Are there certain arctic species that are more vulnerable than otherss? Another question I have is what steps we can take to mitigate toxic algal blooms. Is there any way to prevent them from occurring?
ReplyDeleteThis is a really interesting topic! This was a really good review of the overall topic, journal article, and news article. I’m familiar with the risks of toxic algal blooms because there are always a lot of awareness for dog owners, especially around bodies of water that might have an issue and on the local news. I’m curious what kind of public awareness or public health guidance there is for this specific algal bloom, which disproportionately affects Native Americans. Do you think a community engaged research approach and/or a public health campaign could help reduce potential exposures?
ReplyDeleteOverall, it’s new to me to see algal blooms in the Arctic because I’ve only heard of them being an issue in warm places with a lot of nutrients. This really combines the physics, chemistry, and biology being affected by climate change!