Using a combination of time-series data spanning two decades, the new study shows that oscillations to positive, or warm-favorable conditions in natural climate cycles can reduce the strength of the south-flowing California Current. This allows more movement northwards of both warmer waters and higher levels of toxic plankton, and also brings that toxic mix closer to shore where it can infiltrate shellfish.
Beyond problems with domoic acid levels, White said, this correlation appears to mirror problems with green crabs, an invasive species of significant concern in the Pacific Northwest. These same warm climate phases lead to increased numbers of green crabs in Oregon waters, where they compete with native Dungeness crabs. The conditions also deliver communities of lipid-poor "copepods," types of small crustaceans that float with currents, from the south, that are associated with reduced salmon runs.
"Part of the concern is that a large influx of the plankton that produce domoic acid can have long-term impacts," Morgaine McKibben, an OSU doctoral student and lead author on the study, was quoted as saying in a news release. "For example, razor clams are filter-feeders that bioaccumulate this toxin in their muscles, so they take much longer to flush it out than other shellfish. The higher the toxin levels, the longer it takes for razor clams to be safe to eat again, perhaps up to a year after warm ocean conditions have subsided."
Produced by the diatom genus Pseudo-nitzschia, domoic acid enters the marine food web when toxic blooms of these micro-algae are ingested by animals such as anchovies and shellfish. First identified as a public health threat in 1987 and referred to as "amnesic shellfish poisoning," human symptoms can range from gastrointestinal disturbance to seizures, memory loss or, rarely, death.
【国际英语资讯:Correlation identified between domoic acid shellfish toxicity and warm-water ocean conditions】相关文章:
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