Paralytic shellfish poisoning toxins in butter clams (Saxidomus gigantea) from the Kodiak Archipelago, Alaska

Steven R Kibler; R Wayne Litaker; Julie A Matweyou; D Ransom Hardison; Bruce A Wright; Patricia A Tester

doi:10.1016/j.hal.2021.102165

Paralytic shellfish poisoning toxins in butter clams (Saxidomus gigantea) from the Kodiak Archipelago, Alaska

Harmful Algae. 2022 Jan:111:102165. doi: 10.1016/j.hal.2021.102165. Epub 2021 Dec 25.

Authors

Steven R Kibler¹, R Wayne Litaker², Julie A Matweyou³, D Ransom Hardison⁴, Bruce A Wright⁵, Patricia A Tester⁶

Affiliations

¹ National Oceanic and Atmospheric Administration, National Ocean Service, Beaufort Laboratory, 101 Pivers Island Road, Beaufort, North Carolina, United States of America. Electronic address: steve.kibler@noaa.gov.
² CSS Inc. (Under Contract to National Oceanic and Atmospheric Administration, National Ocean Service, National Centers for Coastal Ocean Science, 1305 East-West Highway, Silver Spring, MD 20910, United States of America).
³ Alaska Sea Grant Marine Advisory Program, Kodiak Seafood and Marine Science Center, 118 Trident Way, Kodiak, Alaska, 99615, United States of America.
⁴ National Oceanic and Atmospheric Administration, National Ocean Service, Beaufort Laboratory, 101 Pivers Island Road, Beaufort, North Carolina, United States of America.
⁵ Knik Tribe of Alaska, 1744 Prospect Drive, Palmer, Alaska, 99645, United States of America.
⁶ Ocean Tester, LLC, 295 Dills Point Road, Beaufort, North Carolina, 28516, United States of America.

PMID: 35016769
DOI: 10.1016/j.hal.2021.102165

Abstract

Consumption of toxic butter clams (Saxidomus gigantea) is the most frequent cause of paralytic shellfish poisoning (PSP) in Alaskan coastal communities. This study examines seasonal variation in total paralytic shellfish toxin concentrations and congener distribution in tissues of butter clams collected in three communities in the Kodiak Islands, Alaska: the City of Kodiak, Ouzinkie and Old Harbor. In response to questions from local harvesters, the efficacy of removing particular clam tissues on total toxin levels was also assessed. Butter clam samples were collected ∼monthly during 2015-2020 in each community to monitor shellfish toxin levels. Results were combined with clam monitoring data collected previously (2013-2015) to document the seasonal distribution of saxitoxin (STX) and its congeners (neosaxitoxin, gonyautoxin) in clam tissues. Seasonally, paralytic shellfish toxin levels in butter clams were highest in summer, declined in winter, but often remained above regulatory limits throughout the year in the three Kodiak communities. Butter clams collected from Ouzinkie (2013-2020) averaged 165 ± 87 µg STX equivalents (Eq.) 100 g ^- ¹, compared to Kodiak 73 ± 54 µg STX Eq. 100 g ^- ¹ and Old Harbor 143 ± 103 µg STX Eq. 100 g ^- ¹. STX accounted for 59-71% of the total toxin concentration in clams at Ouzinkie, Kodiak, and Old Harbor, while neosaxitoxin (neoSTX) accounted for 12-18%. Gonyautoxins (GTXs) represented 31-60% of the total toxin concentration during the seasonal Alexandrium catenella bloom in June-July, with lower percentages in other months. The fraction of total toxin varied among clam tissues: the siphon tip (2-29%), the neck (3-56%), the gut (3-65%) and the body (6-85%). Removal of the siphon tip reduced total toxin content substantially in some samples but had little effect in others. Saxitoxin congeners varied greatly and somewhat unpredictably among clam tissues, and the results indicate removal of specific tissues was not an effective strategy for reducing paralytic shellfish toxin levels in butter clams for safe consumption.

Keywords: Alexandrium, gonyautoxin (GTX); Neosaxitoxin (neoSTX); Saxitoxin (STX); Subsistence.

Published by Elsevier B.V.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Alaska
Animals
Bivalvia*
Butter
Dinoflagellida*
Shellfish Poisoning*

Substances

Butter