Dungeness crabs for sale at Fisherman's Wharf in San Francisco. California's Dungeness crab season was shut down in 2015, when record high ocean temperatures and lingering toxic algae blooms raised the domoic acid in shellfish to unsafe levels. A new study links dangerously high levels of the neurotoxin to warmer ocean temperatures, suggesting such closures could become more common in the future. Eric Risberg/AP hide caption

toggle caption
Eric Risberg/AP

Officials found the toxin microcystin in the blue-green algae present at Discovery Bay, Calif. For people exposed to the toxin, symptoms include dizziness, rashes, fever, vomiting and in more unusual cases, numbness. Lesley McClurg/KQED hide caption

toggle caption
Lesley McClurg/KQED

Poisonous Algae Blooms Threaten People, Ecosystems Across U.S.

  • Download
  • <iframe src="https://www.npr.org/player/embed/491831451/491848138" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

Freshly cooked Dungeness crab sits on a pot of boiling water at Nick's Lighthouse Restaurant in San Francisco, Nov. 5, 2015. Justin Sullivan/Getty Images hide caption

toggle caption
Justin Sullivan/Getty Images

Paul Herringshaw says farmers like him have been taking steps to reduce crop runoff for years. Sarah Jane Tribble/WCPN hide caption

toggle caption
Sarah Jane Tribble/WCPN

Lake Erie's Toxic Bloom Has Ohio Farmers On The Defensive

  • Download
  • <iframe src="https://www.npr.org/player/embed/338936920/338948769" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript