According to the National Oceanic and Atmospheric Administration, a neurotoxin produced by algal blooms is sickening hundreds of sea lions and dolphins along Southern California beaches. Responders are struggling to keep up with the alarming rate at which dead and distressed animals are appearing, and point to climate change as a potential culprit.
“We are managing more than 200 reports of marine mammals in distress each day,” said Ruth Dover, co-founder and managing director of The Channel Islands Marine & Wildlife Institute. “We are doing the best we can to keep up with the intense pace. Please continue to report all sick and injured marine mammals as we are getting to as many animals as we can, as quickly as we can, each day.” The Institute is part of the West Coast Marine Mammal Stranding Network, which is coordinated by NOAA Fisheries and responds to live marine mammal strandings in Ventura and Santa Barbara Counties.
Responders believe a neurotoxin called domoic acid is responsible for the deaths, as the NOAA reports. Rapid growth of the algae Pseudo-nitzschia causes the production of the toxin, which is then transferred into the marine food web. Animals such as shellfish, anchovies and sardines consume the toxin, which eventually accumulates in seabirds and marine mammals when they eat affected prey. Though researches arrived at this hypothesis based on neurological symptoms exhibited by the stranded animals, tissue samples have been collected to test and confirm.
“They eat a meal of those highly toxic fish and then they become toxified themselves, and if they get enough of that material, it of course can kill them, which is happening now,” David Caron, a biological sciences professor at the University of Southern California, told the BBC.
Because domoic acid is a neurotoxin, the animals can become disoriented or even convulse and die under water. However, as the BBC reports, the toxin can also prove dangerous for humans if they consume fish tainted by domoic acid. However, these levels are monitored by the California Department of Public Health, which closes shellfish beaches when necessary, Dr. Caron told the BBC.
If beachgoers do encounter one of the stranded animals affected by the bloom, the NOAA warns to not approach them. The animals can carry the toxin, as well as other diseases that can affect pets.
Algal blooms are a seasonal issue that usually affect California between March and June. However, climate change may be worsening the problem by making more waters warm enough to become habitable for harmful algae blooms. “We have a fair amount of evidence, especially in inland waters,” Dr. Caron told the BBC, “that climate change is exacerbating some of the problems that we’re seeing with harmful algae.”
