Stability of Domoic Acid in 50% Methanol Extracts and Raw Fecal Material from Bowhead Whales (Balaena mysticetus)

Domoic acid (DA), the toxin causing amnesic shellfish poisoning (ASP), is produced globally by some diatoms in the genus Pseudo-nitzschia. DA has been detected in several marine mammal species in the Alaskan Arctic, raising health concerns for marine mammals and subsistence communities dependent upon them. Gastrointestinal matrices are routinely used to detect Harmful Algal Bloom (HAB) toxin presence in marine mammals, yet DA stability has only been studied extensively in shellfish-related matrices. To address this knowledge gap, we quantified DA in bowhead whale fecal samples at multiple time points for two groups: (1) 50% methanol extracts from feces, and (2) raw feces stored in several conditions. DA concentrations decreased to 70 +/- 7.1% of time zero (T-0) in the 50% methanol extracts after 2 weeks, but remained steady until the final time point at 5 weeks (66 +/- 5.7% T-0). In contrast, DA concentrations were stable or increased in raw fecal material after 8 weeks of freezer storage (-20 degrees C), at room temperature (RT) in the dark, or refrigerated at 1 degrees C. DA concentrations in raw feces stored in an incubator (37 degrees C) or at RT in the light decreased to 77 +/- 2.8% and 90 +/- 15.0% T-0 at 8 weeks, respectively. Evaporation during storage of raw fecal material is a likely cause of the increased DA concentrations observed over time with the highest increase to 126 +/- 7.6% T-0 after 3.2 years of frozen storage. These results provide valuable information for developing appropriate sample storage procedures for marine mammal fecal samples.

Automated summary

This study quantified the stability of domoic acid (DA) in bowhead whale fecal samples under various conditions. Results showed that DA concentrations decreased to 70% in 50% methanol extracts after 2 weeks, but remained stable or increased in raw feces after 8 weeks. Evaporation during storage may contribute to increased DA concentrations over time.