Gulf of Alaska | Seabirds
Evaluating the sublethal and chronic effects of saxitoxin ingestion by common murres Presenter: Matthew Smith , mmsmith@usgs.gov, U.S. Geological Survey, Alaska Science Center Caroline Van Hemert , cvanhemert@usgs.gov, U.S. Geological Survey, Alaska Science Center Robert Dusek , rdusek@usgs.gov, U.S. Geological Survey, National Wildlife Health Center
Tuula Hollmen , tuulah@alaskasealife.org, Alaska SeaLife Center Kristen Pelo , kristenp@alaskasealife.org, Alaska SeaLife Center Aidan Lee , aidanl@alaskasealife.org, Alaska SeaLife Center Jenna Schlener , jennas@alaskasealife.org, Alaska SeaLife Center Dave Kulis , dkulis@whoi.edu, Woods Hole Oceanographic Institution Donald Anderson , danderson@whoi.edu, Woods Hole Oceanographic Institution Sherwood Hall , sherwood.hall@fda.hhs.gov, U.S. Food and Drug Administration
Saxitoxins (STXs) are a group of highly potent neurotoxins produced by certain marine dinoflagellate species during harmful algal bloom (HAB) events. These toxins, which are of growing concern in northern waters as temperatures increase, can cause illness or death in a broad suite of wildlife species including fish, seabirds, and marine mammals. Since 2014, widespread seabird mortality events have occurred annually in Alaskan waters. While starvation has often been identified as the proximate cause of death, STXs have been detected in many opportunistically collected carcasses. Interpretation of these values has proven difficult, however, due to a lack of knowledge about the toxicity of STXs in seabirds. To address these information gaps and investigate the behavioral effects of sublethal STX exposure on seabirds, we conducted experimental dosing trials with Common Murres ( Uria aalge ), a seabird species that has been subject to multiple die-off events over the past few years. We administered purified saxitoxin (STX-diHCL) and a crude toxin extract from a strain of Alexandrium catenella isolated from the Chukchi Sea to birds via oral gavage. Using a modified up-and-down dose-finding scheme, we calculated the median effective dose (ED50) for purified STX-diHCL and the crude toxin extract based on the appearance of ecologically relevant behavior, including vomiting, motor discoordination, and paralysis. We also conducted a chronic dosing trial, in which murres were fed fish injected with lower levels of toxin twice daily over a period of seven days to determine possible longer-term effects of STX ingestion. Using a combination of enzyme-linked immunosorbent assay and high-performance liquid chromatography techniques, we analyzed tissue, serum, and fecal samples from euthanized birds for toxin concentrations and congener profiles. These results will provide a better understanding of the direct effects STXs have on seabirds and will help evaluate whether sublethal exposure can inhibit birds’ mobility or access to food in the wild, thereby compromising seabird health without inducing acute toxicity. Additionally, analysis of tissues and fecal samples from experimental birds will facilitate interpretation of values from field-collected samples.
Alaska Marine Science Symposium 2023 22
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