July 29, 2021 — Paralytic shellfish poisoning, caused by eating seafood contaminated with toxins from harmful algal blooms, can be deadly to humans. Now, using marine samples from Unalaska, scientists are trying to understand if those harmful algal blooms could also be responsible for seabird die-offs.
There’s not much data on how saxitoxin — a harmful compound produced by algal blooms that cause PSP — spreads through the larger food web. But in July, a group of biologists with the United States Geological Survey visited Unalaska to collect samples of plants and animals in hopes of learning more about how saxitoxin levels magnify and diminish as they move through the food chain, from phytoplankton to mussels and up to seabirds.
“We don’t really know how this toxin moves through the food web,” said Sarah Schoen, a USGS wildlife biologist that recently collected marine samples in Unalaska. “There’s still a lot of unknowns, but the more information we can collect about it, the more we’ll understand it.”
Schoen said the project started about five years ago when a major heat wave, known as “the blob,” hit the ocean. Around the same time, there was a die-off of an estimated million common murres — a northern seabird — from Alaska down to California.