Naturally occurring etiologic factors affecting the health of breeding seabirds in the Bering Sea

Abstract

Seabird populations across the globe have experienced both significant instability and consistent overall declines in recent history. Seabirds in the Bering Sea of Alaska, USA appear to be severely affected by environmental changes, exhibiting large-scale shifts in behavior and distribution and increases in unusual mortality events (UMEs) in recent years. I analyze a selection of the naturally occurring pathogenic and toxicological factors affecting breeding seabirds in the Bering Sea region using an approach focusing on zoonoses and bioaccumulating toxins. Specimens were collected at three breeding colonies in the Bering Sea in 2018 and 2019, and were evaluated for the presence of several pathogens and toxins. First, I examined the frequency of Influenza A Virus (IAV) in several understudied clades of seabird host species (n=146 individuals) across the Bering Sea. Second, I used a novel set of genetic amplification and sequencing techniques for metagenomic analysis both to determine the respiratory microbiome and to detect the presence of potentially pathogenic microorganisms in northern fulmars (Fulmarus glacialis) on St. Matthew and Hall islands (n = 15). Finally, I sought to evaluate the levels of paralytic shellfish toxins (PSTs) in the digestive tracts of northern fulmars from St. Matthew and Hall islands (n = 14). Together, these studies detected several viral and bacterial pathogens, many with zoonotic potential. These included Coxiella, Plasmodium, Toxoplasma, and IAV. PSTs were also detected in birds sampled from 2019, indicating the presence of harmful algae in the Beringian food web. The detection of these etiologic factors along with the incidence of major morbidity and mortality events suggest these birds might serve as sentinel species, indicating variations in environmental change that can pose a significant risk to both ecological stability and human health in the region.