Elevated ocean temperatures are linked to the development of harmful algal blooms (HABs). Toxins from these blooms may pose health threats to marine organisms, including seabirds. Since 2015, the USGS has worked with a variety of stakeholders to develop testing methods and research projects to better understand the geographic extent, timing and impacts of algal toxins in Alaska marine ecosystems, including possible links to recent seabird die-offs.
Return to Ecosystems >> Wildlife Disease and Environmental Health
What are harmful algal blooms (HABs)?
Certain species of phytoplankton produce biotoxins that can injure or kill fish and wildlife. When blooms of these phytoplankton occur, toxins become distributed throughout the food web. These events, termed harmful algal blooms or HABs, are often related to higher seawater temperatures and changes in ocean currents and nutrient levels. There are two primary marine HAB toxins of concern in Alaska: saxitoxin (STX), which is responsible for causing paralytic shellfish poisoning, and domoic acid (DA), which can cause seizures and other neurological distress.
(Credit: Sarah Schoen, USGS, Alaska Science Center)
Why are we testing birds for algal toxins?
Since 2014, widespread seabird die-off events have been observed annually throughout Alaska; although starvation has been commonly reported, other underlying factors remain unknown. The USGS is the scientific research agency for the Department of the Interior and has developed studies and testing capabilities to address concerns around seabird die-off events. Recent studies in Alaska, including those by USGS, have found STX and DA throughout the marine ecosystem, including in marine mammals, birds, and other wildlife. Increased occurrence of HABs is predicted with changing environmental conditions, including warming ocean temperatures.
What have we learned so far?
We’ve tested nearly twenty Alaska seabird species—including Common Murres, Black-legged Kittiwakes, Northern Fulmars, Short-tailed Shearwaters, and Arctic Terns—for STX and DA. We’ve also tested a variety of forage fish and marine invertebrates. We’ve detected STX commonly in seabird tissues, forage fish, and marine invertebrates throughout Alaska waters, including in the Gulf of Alaska, Bering Sea, and Chukchi Sea. DA has been present less frequently in our samples. In most cases, STX concentrations measured in seabird tissues have been relatively low. We investigated the potential role of HAB toxins in a massive die-off of Common Murres in Alaska in 2015 and 2016 and detected STX in both die-off and healthy birds. However, starvation appeared to be the primary cause of death and the role of HAB toxins is unclear. To date, the highest concentrations of STX have been observed in Northern Fulmars in the Northern Bering Sea and Arctic Terns in Southeast Alaska. Although we don’t know whether STX caused acute mortality in these birds, tissue concentrations were similar to those observed in other bird mortality events attributed to STX, suggesting potentially harmful effects. Within the seabirds we’ve tested, STX has been present in multiple tissues, with the highest concentrations typically found in the gastrointestinal tract.
What do our results mean for seabirds?
Seabirds in Alaska are commonly exposed to STX and DA in the marine environment. How much toxin birds ingest depends on what they eat, where they live, and whether local environmental conditions are suitable for producing HABs. We don’t yet know how sensitive seabirds are to STX but results from a laboratory study of Mallards and Zebra Finches suggests that current levels of exposure in Alaska may be harmful to some species. We are working to address this question for seabirds, which will help us determine the threat of HABs to wild bird populations in Alaska.
What are the implications for human health?
Because humans also consume marine organisms, and in some cases rely heavily on these resources for subsistence, economic, and cultural purposes, HABs have the potential to impact human health. Although our testing and diagnostic tools cannot evaluate food safety, results from seabird research help inform general patterns of HAB occurrence. Our results suggest that bird tissues other than the gastrointestinal tract typically have very low toxin concentrations. Like other recent studies, we have detected algal toxins in wildlife across large geographic areas in Alaska, suggesting that HABs should be considered for any harvesting efforts throughout the state.
What are we doing now?
We work closely with partners and stakeholders to respond to their questions about HABs in Alaska ecosystems. Learn more about ongoing research on how harmful algal toxins affect wild seabirds in a recorded talk by Sarah Schoen and Matt Smith: Harmful algae and seabirds - Strait Science, March 30 2023. Our current HAB toxin research includes both field and laboratory studies to address the following topics:
- Experimental trials to determine the effects of STX on seabird behavior and health.
- Investigating the role of HAB toxins in seabird die-off events to answer the question: Has exposure contributed to bird mortality?
- Tracking occurrence of STX and DA in seabirds throughout Alaska. Where and in which species do these toxins occur?
- Understanding food web dynamics of STX and DA. How do algal toxins move from marine invertebrates and forage fish to higher-level consumers like seabirds?
USGS Alaska Science Center biologists are also studying changes in the food web that have contributed to recent seabird die-offs and consequences of marine heat waves for fish and wildlife populations.
Where can I find more information?
See information in the tabs at the top of this page.
Below are other science projects associated with this project.
Seabird Die-offs in Alaska
Seabirds and Forage Fish Ecology
Algal Toxins and Wildlife Health
Below are data or web applications associated with this project.
Tissue Concentrations and Congener Profiles of Harmful Algal Toxins in Seabirds, Forage Fish, and Other Organisms
Below are multimedia items associated with this project.
Below are publications associated with this project.
Paralytic shellfish toxins associated with Arctic Tern mortalities in Alaska
Harmful algal blooms in the Alaskan Arctic: An emerging threat as oceans warm
Investigation of algal toxins in a multispecies seabird die-off in the Bering and Chukchi seas
Extreme mortality and reproductive failure of common murres resulting from the northeast Pacific marine heatwave of 2014-2016
Algal toxins in Alaskan seabirds: Evaluating the role of saxitoxin and domoic acid in a large-scale die-off of Common Murres
Unusual foraging observations associated with seabird die-offs in Alaska
Fatal paralytic shellfish poisoning in Kittlitz's Murrelet (Brachyramphus brevirostris) nestlings, Alaska, USA
Below are news stories associated with this project.
Below are partners associated with this project.
- Overview
Elevated ocean temperatures are linked to the development of harmful algal blooms (HABs). Toxins from these blooms may pose health threats to marine organisms, including seabirds. Since 2015, the USGS has worked with a variety of stakeholders to develop testing methods and research projects to better understand the geographic extent, timing and impacts of algal toxins in Alaska marine ecosystems, including possible links to recent seabird die-offs.
Return to Ecosystems >> Wildlife Disease and Environmental Health
What are harmful algal blooms (HABs)?
Certain species of phytoplankton produce biotoxins that can injure or kill fish and wildlife. When blooms of these phytoplankton occur, toxins become distributed throughout the food web. These events, termed harmful algal blooms or HABs, are often related to higher seawater temperatures and changes in ocean currents and nutrient levels. There are two primary marine HAB toxins of concern in Alaska: saxitoxin (STX), which is responsible for causing paralytic shellfish poisoning, and domoic acid (DA), which can cause seizures and other neurological distress.
Black-legged Kittiwakes forage on Pacific sand lance and capelin near their colony on Gull Island, Cook Inlet on June 28, 2018.
(Credit: Sarah Schoen, USGS, Alaska Science Center)Why are we testing birds for algal toxins?
Since 2014, widespread seabird die-off events have been observed annually throughout Alaska; although starvation has been commonly reported, other underlying factors remain unknown. The USGS is the scientific research agency for the Department of the Interior and has developed studies and testing capabilities to address concerns around seabird die-off events. Recent studies in Alaska, including those by USGS, have found STX and DA throughout the marine ecosystem, including in marine mammals, birds, and other wildlife. Increased occurrence of HABs is predicted with changing environmental conditions, including warming ocean temperatures.
What have we learned so far?
We’ve tested nearly twenty Alaska seabird species—including Common Murres, Black-legged Kittiwakes, Northern Fulmars, Short-tailed Shearwaters, and Arctic Terns—for STX and DA. We’ve also tested a variety of forage fish and marine invertebrates. We’ve detected STX commonly in seabird tissues, forage fish, and marine invertebrates throughout Alaska waters, including in the Gulf of Alaska, Bering Sea, and Chukchi Sea. DA has been present less frequently in our samples. In most cases, STX concentrations measured in seabird tissues have been relatively low. We investigated the potential role of HAB toxins in a massive die-off of Common Murres in Alaska in 2015 and 2016 and detected STX in both die-off and healthy birds. However, starvation appeared to be the primary cause of death and the role of HAB toxins is unclear. To date, the highest concentrations of STX have been observed in Northern Fulmars in the Northern Bering Sea and Arctic Terns in Southeast Alaska. Although we don’t know whether STX caused acute mortality in these birds, tissue concentrations were similar to those observed in other bird mortality events attributed to STX, suggesting potentially harmful effects. Within the seabirds we’ve tested, STX has been present in multiple tissues, with the highest concentrations typically found in the gastrointestinal tract.
What do our results mean for seabirds?
Seabirds in Alaska are commonly exposed to STX and DA in the marine environment. How much toxin birds ingest depends on what they eat, where they live, and whether local environmental conditions are suitable for producing HABs. We don’t yet know how sensitive seabirds are to STX but results from a laboratory study of Mallards and Zebra Finches suggests that current levels of exposure in Alaska may be harmful to some species. We are working to address this question for seabirds, which will help us determine the threat of HABs to wild bird populations in Alaska.
What are the implications for human health?
Because humans also consume marine organisms, and in some cases rely heavily on these resources for subsistence, economic, and cultural purposes, HABs have the potential to impact human health. Although our testing and diagnostic tools cannot evaluate food safety, results from seabird research help inform general patterns of HAB occurrence. Our results suggest that bird tissues other than the gastrointestinal tract typically have very low toxin concentrations. Like other recent studies, we have detected algal toxins in wildlife across large geographic areas in Alaska, suggesting that HABs should be considered for any harvesting efforts throughout the state.
What are we doing now?
We work closely with partners and stakeholders to respond to their questions about HABs in Alaska ecosystems. Learn more about ongoing research on how harmful algal toxins affect wild seabirds in a recorded talk by Sarah Schoen and Matt Smith: Harmful algae and seabirds - Strait Science, March 30 2023. Our current HAB toxin research includes both field and laboratory studies to address the following topics:
- Experimental trials to determine the effects of STX on seabird behavior and health.
- Investigating the role of HAB toxins in seabird die-off events to answer the question: Has exposure contributed to bird mortality?
- Tracking occurrence of STX and DA in seabirds throughout Alaska. Where and in which species do these toxins occur?
- Understanding food web dynamics of STX and DA. How do algal toxins move from marine invertebrates and forage fish to higher-level consumers like seabirds?
USGS Alaska Science Center biologists are also studying changes in the food web that have contributed to recent seabird die-offs and consequences of marine heat waves for fish and wildlife populations.
Where can I find more information?
See information in the tabs at the top of this page.
Three Arctic Terns sitting on a log floating in the water in Prince William Sound. (Credit: Sarah Schoen, U.S. Geological Survey) - Science
Below are other science projects associated with this project.
Seabird Die-offs in Alaska
Beginning in 2015, large numbers of dead seabirds have been appearing on beaches in most marine areas of Alaska. Although seabird die-offs are known to occur sporadically (e.g. 1970, 1989, 1993, 1997/1998, and 2004) in Alaska, these recent die-offs have been distinguished from past events by their increased frequency, duration, geographic extent, and number of different species involved.Seabirds and Forage Fish Ecology
Alaska's coastal and offshore waters provide foraging habitat for an estimated 100 million birds comprising more than 90 different species; from loons and seaducks that nest inland, to petrels and puffins that breed on islands off shore. All these birds depend on the sea to provide a wide variety of food types— from clams, crabs and urchins nearshore— to krill, forage fish, and squid offshore. The...Algal Toxins and Wildlife Health
Harmful algal blooms (HABs) have the potential to harm fish and wildlife, domestic animals, livestock, and humans through toxin production or ecological disturbances such as oxygen depletion and blockage of sunlight. - Data
Below are data or web applications associated with this project.
Tissue Concentrations and Congener Profiles of Harmful Algal Toxins in Seabirds, Forage Fish, and Other Organisms
These data are in four tables and contain results from screening tissues of marine organisms for the presence of harmful algal bloom (HAB) toxins: saxitoxin and its related congeners (STX) and domoic acid (DA). Samples collected by USGS or submitted to our laboratory by partners or other stakeholders are screened using commercially-available enzyme linked immunosorbent assays (ELISA). A subset of - Multimedia
Below are multimedia items associated with this project.
- Publications
Below are publications associated with this project.
Paralytic shellfish toxins associated with Arctic Tern mortalities in Alaska
Harmful algal blooms produce biotoxins that can injure or kill fish, wildlife, and humans. These blooms occur naturally but have intensified in many locations globally due to recent climatic changes, including ocean warming. Such changes are especially pronounced in northern regions, where the effects of paralytic shellfish toxins (PSTs) on marine wildlife are of growing concern. In Alaska, seabirAuthorsCaroline R. Van Hemert, John Harley, Gwen Baluss, Matthew M. Smith, Robert J. Dusek, Julia S. Lankton, D. Ransom Hardison, Sarah K. Schoen, Robert KalerHarmful algal blooms in the Alaskan Arctic: An emerging threat as oceans warm
Harmful algal blooms (HABs) present an emerging threat to human and ecosystem health in the Alaskan Arctic. Two HAB toxins are of concern in the region: saxitoxins (STXs), a family of compounds produced by the dinoflagellate Alexandrium catenella, and domoic acid (DA), produced by multiple species in the diatom genus Pseudo-nitzschia. These potent neurotoxins cause paralytic and amnesic shellfishAuthorsDonald Anderson, Evangeline Fachon, Katherine Hubbard, Kathi Lefebvre, Peigen Lin, Robert Pickart, Mindy Richlen, Gay Sheffield, Caroline R. Van HemertInvestigation of algal toxins in a multispecies seabird die-off in the Bering and Chukchi seas
Between 2014 and 2017, widespread seabird mortality events were documented annually in the Bering and Chukchi seas, concurrent with dramatic reductions of sea ice, warmer than average ocean temperatures, and rapid shifts in marine ecosystems. Among other changes in the marine environment, harmful algal blooms (HABs) that produce the neurotoxins saxitoxin (STX) and domoic acid (DA) have been identiAuthorsCaroline R. Van Hemert, Robert J. Dusek, Matthew M. Smith, Robert Kaler, Gay Sheffield, Lauren M. Divine, Kathy J. Kuletz, Susan Knowles, Julia S. Lankton, D. Ransom Hardison, R. Wayne Litaker, Timothy Jones, Hillary K. Burgess, Julia K. ParrishExtreme mortality and reproductive failure of common murres resulting from the northeast Pacific marine heatwave of 2014-2016
About 62,000 dead or dying common murres (Uria aalge), the trophically dominant fish-eating seabird of the North Pacific, washed ashore between summer 2015 and spring 2016 on beaches from California to Alaska. Most birds were severely emaciated and, so far, no evidence for anything other than starvation was found to explain this mass mortality. Three-quarters of murres were found in the Gulf of AlAuthorsJohn F. Piatt, Julia K. Parrish, Heather M. Renner, Sarah K. Schoen, Timothy Jones, Mayumi L. Arimitsu, Kathy J. Kuletz, Barbara Bodenstein, Marisol Garcia-Reyes, Rebecca Duerr, Robin Corcoran, Robb S.A. Kaler, Gerard J. McChesney, Richard T. Golightly, Heather A. Coletti, Robert M. Suryan, Hillary K. Burgess, Jackie Lindsey, Kirsten Lindquist, Peter Warzybok, Jaime Jahncke, Jan Roletto, William J. SydemanAlgal toxins in Alaskan seabirds: Evaluating the role of saxitoxin and domoic acid in a large-scale die-off of Common Murres
Elevated seawater temperatures are linked to the development of harmful algal blooms (HABs), which pose a growing threat to marine birds and other wildlife. During late 2015 and early 2016, a massive die-off of Common Murres (Uria algae; hereafter, murres) was observed in the Gulf of Alaska coincident with a strong marine heat wave. Previous studies have documented illness and death among seabirdsAuthorsCaroline R. Van Hemert, Sarah K. Schoen, R. Wayne Litaker, Matthew M. Smith, Mayumi L. Arimitsu, John F. Piatt, William C. Holland, Ransom Hardison, John M. PearceUnusual foraging observations associated with seabird die-offs in Alaska
We report the first documentation of off-water foraging by the Fork-tailed Storm-Petrel Oceanodroma furcata and Short-tailed Shearwater Ardenna tenuirostris, a behavior not previously documented in any member of the families Hydrobatidae or Procellariidae. Over a two-week period in September 2016, we regularly observed individuals of these species over land on an extensive intertidal zone on the BAuthorsBryce Robinson, Lucas H. DeCicco, James A. Johnson, Daniel R. RuthrauffFatal paralytic shellfish poisoning in Kittlitz's Murrelet (Brachyramphus brevirostris) nestlings, Alaska, USA
Paralytic shellfish poisoning (PSP) is an acute toxic illness in humans resulting from ingestion of shellfish contaminated with a suite of neurotoxins (saxitoxins) produced by marine dinoflagellates, most commonly in the genus Alexandrium. Poisoning also has been sporadically suspected and, less often, documented in marine wildlife, often in association with an outbreak in humans. Kittlitz's MurreAuthorsValerie I. Shearn-Bochsler, Ellen W. Lance, Robin Corcoran, John F. Piatt, Barbara Bodenstein, Elizabeth Frame, James Lawonn - News
Below are news stories associated with this project.
- Partners
Below are partners associated with this project.