A microscopic killer lives in SF’s waters

Researchers find ocean acidification threatens local fisheries

Researchers have identified the microscopic algae,<em> Pseudo-nitzschi, </em>which was responsible for the closure of California’s Dungeness crab season in 2015. (Courtesy C.J. Wingert, San Francisco State University)
Researchers have identified the microscopic algae, Pseudo-nitzschi, which was responsible for the closure of California’s Dungeness crab season in 2015. (Courtesy C.J. Wingert, San Francisco State University)

Outside the Golden Gate Bridge, in California’s coastal waters, lives a killer much smaller than the Great White shark.

A certain microscopic algae, termed Pseudo-nitzschia diatoms, generate a neurotoxin called domoic acid. These diatoms bloom naturally during the spring and summer and can poison marine life and humans that consume contaminated fish and shellfish. While blooms typically disappear by fall, a massive one persisted much longer in 2015 and was responsible for the closure of California’s Dungeness crab season.

Now, new research offers proof that this “abnormal” will happen more in the future, thanks to climate change.

A new study by Cochlan and his former graduate student Charles Wingert fills this information gap. Despite funding limitations and pandemic-related laboratory closures, the team is conducting carefully designed experiments to assess the impact of ocean acidification on the species. They found that as the ocean absorbs more carbon dioxide, corresponding increases in acidification levels will make the algae produce more toxins.

These results, which the journal “Harmful Algae” will publish later this month, highlight the importance of reducing atmospheric carbon dioxide, as well as conducting more robust scientific studies. Very little is known about this tiny killer even though its effects on marine mammals, birds, public health and the economy have been huge. Better investments in science can help communities along the West Coast better adapt to these impacts.

Looking at ocean acidification in combination with other factors was not an easy task before the pandemic. And when their labs shut down due to COVID-19, the team struggled even more to keep specimens viable and the experiments on course.

The hope is that these new scientific results will help policymakers become less reactive to the impacts of climate change and more proactive. There are not many studies on ocean acidification and the impacts it will have on species — specifically, microscopic algae and the ones that produce toxins. Scientists can use this research to better model when and where toxic blooms may occur, which will benefit shellfish growers, fisheries, wildlife and our health.

Robyn Purchia, San Francisco Examiner, 9 June 2021. Full article.


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