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Red tide toxins can also poison seafood and harm people, pets, fish and seabirds
B
y Miriam Raftery
Map, left: Forecast for Saturday, July 1
June 29, 2023 (San Diego) – A red tide containing a toxic algae bloom that has sickened and killed hundreds of sea lions and dolphins off the California coast is forecast to reach San Diego’s beaches as early as tomorrow. By Saturday, July 1st, the red tide will be impacting all San Diego beaches, with levels of the potent neurotoxin domoic acid at double the 500 nanograms per liter considered harmful.
That’s according to the California Department of Fish & Wildlife, which issued a press advisory today with this forecasting tool.
How dangerous is this red tide to marine mammals and other sea life?
The bloom, which began in early June off Santa Barbara, is the “most severe bloom in memory” according to the CDFW. While not all red tides are toxic, depending on the type of algae bloom, this one has wreaked havoc on marine mammals, sickening and killing hundreds in Southern California this month. The neurotoxin in this bloom induces seizures, brain damage, and death in marine mammals that consume fish contaminated with the toxin.
Birds such as cormorants can become sick and die from eating fish or shellfish contaminated by the toxins; in some places, thousands of birds have perished.
The algae blooms also use up oxygen and prevent light from reaching plants on the seabed, potentially harming these as well.
What’s the risk to humans and pets?
The biggest risk to humans from this particular toxic bloom is if a person consumers seafood tainted by domoic acid. Highest risk are filter-feeders such as mussels, clams, oysters, and scallops, according to the California Department of Public Health (CDPH) webpage on red tides. The toxins can also accumulate in anchovies, crabs, lobsters, and sardines.
Seafood can contain harmful levels of marine toxins even if you cannot yet see the red tide. While commercially sold seafood is regularly tested for these toxins, privately caught or harvested seafood poses substantial risk at this time. To learn about current advisories and quarantined areas for sportfishing or harvesting shellfish, call the Biotoxin Information Line (800)-553-4133.
According to the CDPH, red tides can also cause irritation of the eyes, mouth and throat, as well as cold and flu-like symptoms in humans.
The U.S. Centers for Disease Control advises, “The long-term health effects of harmful algal blooms in people and animals remain unclear. Because we are still learning about the long-term health effects, it’s important to take steps to keep yourself and your pets safe, such as not going into water containing harmful algal blooms.”
Pets should not be allowed to swim in any waters with harmful algae, including the ocean and also any lakes or ponds with visible algae scum.
What should I do if I see an ailing sea lion or other marine animal impacted by the toxic algae?
There are reports of sea lions attacking and biting swimmers, surfers and sunbathers in Dana Beach and other Southern California coastal communities, as the neurotoxin affects their brains and can causes aggressive behavior.
The public is urged to stay away from marine mammals and to report injured and ill marine mammals to the National Marine Mammal Foundation in San Diego at https://www.nmmf.org.
Sea World has also already treated several marine mammals sickened by the toxic algae bloom, according to CBS 8. Sea World has also disclosed that exposure to toxic algae is now believed to be a possible cause of death of the famed “freeway sea lion” that wandered onto several major thoroughfares, after toxicology tests found the neurotoxin in its system.
Marine mammals can be treated with fluids, food and anti-inflammatories to flush out toxins. While some fully recover, other survivors may have long-lasting effects, notably brain damage, according to the Channel Islands Marine and Wildlife Institute, USA Today reports.
What are symptoms of toxic algae poisoning in humans, and what should I do if I’m ill?
Poisoning from eating seafood such as shellfish or fish contaminated by toxic algae can include nausea, vomiting, diarrhea, stomach pain, shortness of breath, irregular heartbeat, abnormal hot and cold sensations, memory loss, disorientation, seizures and coma. Treatment is important, especially for older people and anyone with kidney disease.
Call your healthcare provider for help to manage symptoms. For details on illnesses linked to toxic blooms, call the poison control center hotline at 1-800-222-1222. Illness believed to be caused by algal toxins should be reported to your local or state health department, which have forms on their websites.
What’s causing the toxic algae bloom and how long will it last?
The bloom off local shorelines is caused by a diatom, a form of plankton, called Pseudo-nitzschia spp. Such blooms have been accelerating in recent years, with a 15-fold increase in red tides over the past 50 years, Newsweek recently reported.
Photo, right: A prior red tide off San Diego's coast, via Cailf.Dept. of Public Health
Climate change, as well as growing use of chemical agricultural fertilizers that runoff into the sea, are believed to be factors in the disturbing growth in toxic algae blooms, Newsweek reports. The fertilizers serve as nutrients feeding the plankton that fuels colorful but potentially deadly algae blooms.
Red tides carrying different forms of toxic algae have been plaguing the Florida coast for months, where tons of dead fish have washed ashore as well as dead turtles and manatees, also forcing cancellation of a BeachFest event.
Red tides can last for days, weeks or months—and so far, experts have not predicted when the current wave of toxic red tides off California’s coast may end.
For San Diego beachgoers, the red tide toxins are an added frustration, after months of closures and warnings at some local beaches due to contamination from sewage spills in Tijuana,Mexico's aging power plant.
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