When sea lions suffered seizures and birds and porpoises started dying on the California coast last year, scientists weren't entirely surprised. Toxic algae is known to harm marine mammals.
But when researchers found enormous amounts of toxin in a pelican that had been slurping anchovies, they decided to sample fresh-caught fish. To their surprise, they found toxins at such dangerous levels in anchovy meat that the state urged people to immediately stop eating them.
The algae bloom that blanketed the US West Coast in 2015 was the most toxic one ever recorded in that region. But from the fjords of South America to the waters of the Arabian Sea, harmful blooms, perhaps accelerated by ocean warming and other shifts linked to climate change, are wreaking more havoc on ocean life and people. And many scientists project they will get worse.