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    Seabird die-offs in Alaska: Should we be concerned?

    Some of the largest and most diverse seabird populations in the world are found in Alaskan waters. Seabirds are good indicators of ecosystem health in many ways including fish abundance, chemical contamination, particulate pollution, and general oceanic conditions. So the recent increased number of seabird deaths in Homer, the Alaska Peninsula and the eastern edge of the Aleutians Islands, and the massive die-off of common murres (Uria algae) in Kodiak are not good news.Auklets

    Although seabirds can die due to a number of avian diseases, massive mortality is rare in Alaska. In fact, the first large seabird die-off caused by avian cholera outbreak was reported at St. Lawrence Island in 2013. Avian diseases are generally not harmful to humans. That said, if you find a dead seabird on the beach do not touch it without gloves, and if you do, wash your hands thoroughly. Like most animals including humans, seabirds are more prone to disease when they are stressed or in poor body condition. So deaths can often be caused by a combination of a disease and whatever else may be causing the stress such as poor diet, bad weather, human disturbance, or all of the above (Goutte et al. 2010).

    Scientists puzzle whether seabird die-offs are related to the algae blooms that are associated with warming ocean temperatures. A large bloom of toxic algae that produced a neurotoxin called domoic acid, which can be fatal to humans, occurred from California to British Columbia in June 2015. Blooms of toxic algae can have an array of seabird responses ranging from reduced feeding activity, inability to lay eggs, loss of motor coordination, and death (Shumway et al. 2003). Non-toxic algae blooms can also cause massive seabird die-offs such as that reported in Washington in 2007 by reducing the waterproof qualities of the feathers.

    Perhaps the most likely cause of die-offs is simply not enough food. The murre carcasses from Kodiak were emaciated, indicating birds died of poor nutrition possibly caused from starvation, diseases, or both. Bill Sydeman (Farallon Institute), proposed that seabird die-offs in Alaska and the unprecedented die-off of Cassin’s auklets in Washington were possibly a consequence of a massive ‘blob’ of warm water that formed in the North Pacific in late 2014. Changes in ocean temperatures can alter the environment of the zooplankton many fish and birds feed on, and favor algae blooms instead. Although Alaskan seabirds are able to cope to a certain degree by shifting diets (Renner et al. 2012), they may not cope with extreme or prolonged poor conditions. It is not difficult to imagine the effect of global warming on Alaskan food webs. In fact, a 2% annual decline of Alaskan seabird populations possibly mediated by food shortages coincides with an increase in ocean temperatures over the last 30–40 years.

    Why we should care about seabirds?
    Because like us, seabirds play an important role in a functioning ecosystem, and almost certainly whatever has caused the seabird deaths will in some form affect us sooner or later.

    What can we do?COASST
    First, reporting what you see is very useful for helping to determine the causes of seabird mortality. Many communities including St. Paul, report dead seabirds to the Coastal Observation and Seabird Survey Team (COASST) program where the data helps to answer what caused the die-offs. Second, acting to help reduce global warming is something we all can do at home. Every little bit helps. Finally, learning about the environment around you is one of the best ways to notice change. The Seabird Youth Network is doing a great job of this in the Pribilof Islands. Check out this video created by St. Paul youth on the least auklet.

     

    References

    Buchanan KL (2000) Stress and the evolution of condition dependent signals. Trends Ecol Evol 15: 157–160

    Goutte A, Angelier F, Welcker J, Moe B and others (2010) Long-term survival effect of corticosterone manipulation in black-legged kittiwakes. Gen Com Endocrinol 167:246−251

    Renner HM, Mueter F, Drummond B, Warzybok J, Sinclair EH (2012) Patterns of change in diets of two piscivorous seabird species during 35 years in the Pribilof Islands. Deep-Sea Res II 65−70: 273−291

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