Channel Islands Marine & Wildlife Institute (CIMWI) serves Santa Barbara and Ventura counties. CIMWI is receiving elevated reports of sick California sea lions we suspect to be suffering from domoic acid toxicity.
What is domoic acid?
Domoic acid (DA) is often referred to as “Red Tide” and it is produced by a naturally occurring algal bloom. Domoic acid is a neurotoxin (toxin poisonous to nerve tissue) produced by phytoplankton (microscopic marine plants), specifically a microscopic diatom (algae) in the ocean called Pseudonitzschia australis.
The contaminated algae does not directly affect the organisms that consume it which are filter-feeders including small fish (anchovies and sardines), shellfish (crab and shrimp) and bivalves (clams, mussels and oysters). Shellfish and other small fish consume the toxic algae when it is blooming and it accumulates in their bodies. When another member of the food chain consumes this contaminated prey source they are affected by the accumulated toxin. The toxin is then passed through the food chain resulting illness for the animals and humans who have consumed the toxin.
Biomagnification is the increase in concentration of a pollutant from one link in a food chain to another. Many dangerous toxins settle to the seafloor and then are taken in by benthic feeders (organisms that live or feed at the bottom). Sediment on the seafloor can also hold a reservoir of toxin that lasts for months after the algal bloom dissipates and add to future algal blooms when it rises to the surface during upwelling. The toxin from the algae accumulates in the animals that ingest it and the toxin becomes more concentrated as it passes up through the food chain. Top predators will have the highest concentrations of the toxin because they eat larger amounts of prey.
This neurotoxin causes seizures in higher vertebrates as it concentrates up the food chain by targeting the brain. It specifically affects the hippocampus which is a small region of the brain that forms part of the limbic system. The hippocampus is primarily associated with long-term memory and spatial navigation. Damage to the hippocampus can lead to loss of memory and difficulty in establishing new memories as well as learning and storing new information. California sea lions and other marine mammals as well as sea birds become affected when they eat prey like anchovies and sardines that have been feeding on the algae during toxin-producing algal blooms.
The effect of domoic acid on sea lions depends on the amount of contaminated fish they consume. Diagnosis depends on the detection of the poison in serum, urine or feces of affected animals coupled with the detection of Pseudo-nitzschia australis in the environment and prey of affected sea lions.
There is no known cure for domoic acid. Symptoms of acute DA typically subside after 72 hours as the toxin is eliminated from the body in urine. In many cases, sea lions with DA can recover and successfully forage and survive in the wild. CIMWI puts animals suspected of having domoic acid under observation in a safety perimeter to protect the animal and keep people at a distance. Often the affected sea lion will return to the ocean on its own after resting on the beach for 24-72 hours while experiencing the acute phase of the toxin. CIMWI volunteers monitor the animal’s condition and educate the public. Rescue and transport of DA affected animals is very stressful to the animal and may negatively affect the animal’s health and immediate survival. It could also cause a pregnant female to go into premature labor and delivery with a grave prognosis for the fetus. In cases where CIMWI determines it is appropriate to intervene, trained volunteers will rescue the animal and transport it to CIMWI’s rehabilitation facility for our veterinary team to evaluate and determine the course of action for the individual animal and situation.
What are the symptoms of domoic acid?
California sea lions are the most common pinniped exposed to domoic acid poisoning due to their habitat and locations of their foraging sites. Sea lions are affected by domoic acid when they consume contaminated prey sources.
There are a variety of signs and symptoms of domoic acid toxicity that present within 24 hours of contaminated fish consumption. They include lethargy, disorientation (unaware of human/animal presence, moving around aimlessly), head bobbing and weaving, foaming at the mouth, vomiting, eyes bulging, muscle spasms, seizures, unresponsiveness, the inability to move out of the water and in severe cases death. It is important to remember that these are wild animals and although they may appear lethargic or unresponsive they could respond aggressively and may bite if they are approached.
Pregnant sea lions are more susceptible to domoic acid poisoning if they are foraging where the harmful algal bloom is present because of the increased amount of food they consume. The toxin is passed through the placenta in utero to their developing fetus and through nursing after giving birth. Domoic acid has been associated with premature births and prenatal mortality (stillbirths and death within first week of life).
What is the cause of domoic acid?
Domoic acid is produced by a naturally occurring algal bloom and the toxin does not present danger when it exists in small quantities. It becomes dangerous when it is an extensive bloom and is consumed through the food chain which causes harm to fish, marine mammals, birds, humans and the ecosystems where the algal bloom occurs. This is referred to as a harmful algal bloom (HAB) which is when colonies of toxic microscopic algae grow out of control.
Pseudo-nitzschia blooms typically occur during the transitional periods in the spring and fall when upwelling is starting or winding down. This is when the upwelling of cold water causes the nutrients from deeper water to rise to the surface where sunlight is present producing favorable conditions for the growth phytoplankton in our coastal ecosystem. The warm-water anomaly known as the “warm blob” proliferates algal blooms as the warm water interacts with coastal upwelling creating favorable conditions for a toxic bloom of Pseudo-nitzschia.
The coastal ocean is changing rapidly as it responds to natural and anthropogenic change. The frequency and severity of HAB events along Southern California’s coast has been increasing in recent decades. Climate change and increasing nutrient pollution are environmental circumstances that are potentially causing HABs to occur more often and in locations not previously affected. El Niño brings warm water conditions that can promote higher toxic algae blooms and unusual oceanographic conditions unrelated to El Niño can also lead to algal bloom. Eutrophication is excessive richness of nutrients in bodies of water that cause a dense growth of plant life and death of animal life from lack of oxygen and it is frequently associated with fertilizers, agricultural and urban runoff, aquaculture activity and coastal development.
Scientists are researching how and why HABs form and where they are so efforts can be made to reduce their harmful effects. HABs affect the health of marine ecosystems and people as well as the health of our economy because fishing, fish and shellfish consumption and income from jobs, sales and tourism are negatively impacted.
Does domoic acid affect humans?
Marine mammals are sentinels of ocean health and can alert us to potentially dangerous environmental changes in the ocean. Sick and stranded marine mammals warn us about changing ocean conditions. Marine mammals that have been poisoned by domoic acid help protect human health by demonstrating the need for screening shellfish and other seafood for biotoxins.
In humans, domoic acid is referred to as Amnesic Shellfish Poisoning (ASP) which is caused by the consumption of contaminated shellfish. ASP causes a variety of signs and symptoms and their severity can vary. These signs and symptoms include vomiting and diarrhea within 24 hours of eating the contaminated shellfish, dizziness, headache, disorientation and short-term memory loss. In severe cases seizures, weakness, paralysis and death can occur.
For information regarding seafood advisories, visit the Environmental Protection Agency’s (EPA) “Choose Fish and Shellfish Wisely” web page, as well as the California Department of Fish and Wildlife’s “Health Advisories and Closures for California Finfish, Shellfish and Crustaceans” web page.
What should people do if they encounter a marine mammal that they think may have domoic acid or a stranded marine mammal that is sick, injured, malnourished, entangled, deceased or oiled?
There are 4 steps to follow to help a stranded marine mammal:
1. Do Not Touch!
Do not touch, feed, harass, cover, pour water on, allow dogs near or coax/drag/push/pull/roll the animal into the water or out of the surf zone. Returning a sick animal to the water may affect its immediate survival.
2. Observe Animal
Observe the animal from a minimum of 50 feet. Keep people and pets away from the stranded animal. Observe the animal and note its physical characteristics and condition.
3. Determine Location
Determine the exact location of the animal. Be as accurate as possible and note any landmarks so CIMWI’s rescue team can easily find the animal.
4. Call Hotline
Call the CIMWI Rescue Hotline at (805) 567-1505. Provide your name, phone number, specific information about the animal and its location.
If you find a live stranded dolphin, porpoise or whale, it is critical to contact CIMWI’s Hotline immediately. Do not attempt to push the animal back into the water. When these animals strand on the beach they are potentially critically ill and in need of veterinary care. CIMWI volunteers put live cetacean strandings as a priority and will be on-site as quickly as possible. While waiting for CIMWI volunteers to arrive, please follow these steps:
- Protect the animal’s skin from sunlight and keep it wet by gently putting wet towels over the animal’s body.
- Shade the animal’s eyes from sunlight but do not put anything directly on the eyes or dolphin’s head.
- Pour ocean water over the towels protecting the animal’s body and head. It is critical that water does not get near or into the blowhole on top of the animal’s head.
- If possible dig shallow trenches under the pectoral (front) flippers to relieve pressure.
What is important to NOT do if you encounter a stranded marine mammal?
If you find a stranded marine mammal, do not touch it, do not attempt to get it back into the water and do not attempt to rescue it. Marine mammals are federally protected under the Marine Mammal Protection Act. It is illegal to touch, feed or harass a marine mammal. Violations can result in a civil penalty up to $11,000 as well as criminal penalties up to $100,000 and imprisonment of up to a year or both.
Not all animals on the beach need human intervention. It is normal for seals and sea lions to come out of the water (“haul out”) to rest, digest and sun themselves and mothers often leave their pups onshore while they are foraging at sea. It is in the best interest of these wild animals to have the least amount of human interaction as possible. Interfering is illegal and could negatively impact the immediate health of the animal and/or cause harm to the people interacting with the animal. Observe the animal from a minimum distance of 50 feet for human and animal safety. It is important to note that these are wild animals and they may bite. Marine mammals can also carry zoonotic diseases harmful to humans and pets. Report the stranded animal to CIMWI’s Hotline (805) 567-1505. A trained volunteer will be dispatched to assess the animal and situation.
Do not take actions that are illegal or could add additional stress for the stranded animal. These are wild animals and they are sick. People and dogs crowding the animal can add additional stress, cause harm to the animal and affect its immediate survival. Keep your distance (stay 50 feet away from the animal) and help keep other people and dogs away from the animal. Do not get close to the animal to take selfies, do not pet the animal, do not put a child on top of the animal to take photos, do not lie next to the animal. Do not coax/drag/push/pull/roll the animal into the water or out of the surf zone. Returning a sick animal to the water may affect its immediate survival and people can get injured trying to move an animal.
What can people do to help the health of our ocean which affects the health of marine mammals and humans?
Human waste and toilet paper are the only things that should be flushed down the toilet. Throw everything else in the trash or recycle it. Products labeled as “flushable” might go down the toilet but they do not break down easily. Do not pour fats, oil and grease down the sink. It goes down the sink but causes build up and damage along the way. Sewers are designed to carry water, human waste and toilet paper, period.
Human activities contribute to the extensive and increasing quantities of consumer, industrial, agricultural and sewage flowing to coastal waters. The effects of this pollution alter the size and composition of the nutrient pool which in turn creates a more favorable nutrient environment for certain HAB species. Fertilizers for agricultural production are a source of nutrient pollution in coastal waters and they can promote the growth of HABs.
Personal steps people can take to decrease nutrient pollution include:
- Only flush human waste (urine and feces) and toilet paper in the toilet. Throw everything else in the trash or recycle it.
- Do not flush products that are labeled “flushable” in the toilet. These products are not biodegradable like toilet paper and they clog drains and sewers and litter oceans.
- This is a list of common items that often get flushed down the toilet and none of these items should be flushed down the toilet: cleaning/wet wipes, facial tissue, paper towels, napkins, cotton balls and swabs, dental floss, disposable diapers, sanitary napkins, tampons, tampon applicators, condoms, band-aids, automotive fluids, poisons, hazardous waste and cigarette butts.
- Do not flush medication! Sewage systems cannot remove these drugs from water that is released into lakes, rivers or oceans. Fish and other aquatic animals have shown adverse effects from medicines in the water. The National Prescription Drug Take Back Day aims to provide a safe, convenient and responsible means of disposing of prescription drugs. Search for a Collection Site near you, https://www.deadiversion.usdoj.gov/drug_disposal/takeback/.
- The pathogens in pet waste are harmful to the health of humans, animals and the environment. Dispose of it in the trash.
- Do not flush cat feces with or without accompanying cat litter. It may contain parasites that can cause health problems in susceptible humans (i.e. pregnant women and people with compromised immune systems) and marine life. Wastewater treatment does not remove the parasites and they can get into rivers and oceans.
- Do not flush dog waste down the toilet. Wastewater treatment systems are not designed to filter dog waste. Pick up and throw dog feces in the trash. Dog feces carry toxic bacteria that seeps into the soil. The dangerous pathogens pollute our freshwater supply. Dog poop is the #3 cause of water pollution.
- Do not pour fats, oils or grease down the sink. Let it cool and pour it into a glass jar or aluminum can, let it harden in the refrigerator and then throw it in the trash.
- Excess nutrients in lawn fertilizer can enter our waterways and reach the ocean. Choose your fertilizer wisely and minimize the frequency of application.
- Water entering storm drains does not undergo treatment before it is discharged into our waterways. When cars are washed on streets and driveways, the dirty water winds up in rivers, streams, creeks, lakes and ultimately the ocean. Pollution associated with car washing degrades water quality while also finding its way into sediments which impact aquatic habitats.
Domoic acid poisoning is emerging as a key threat this year to the marine mammals and birds that have ingested fish that have bioaccumulated the Pseudo-nitzschia neurotoxin. This is the most severe algal bloom with domoic acid producing diatoms that CIMWI has experienced since our inception in June 2006.
Channel Islands Marine & Wildlife Institute is dedicated to positively impacting conservation through marine mammal rescue, rehabilitation, research and education to promote ocean and human health. CIMWI’s core work is the rescue and rehabilitation of sick, injured, malnourished, orphaned, entangled and oiled marine mammals. CIMWI is the only organization authorized by NOAA Fisheries to respond to live and dead pinnipeds (sea lions and seals), live and dead sea turtles, and live cetaceans (whales, dolphins and porpoises), rehabilitate live pinnipeds, and triage live cetaceans and sea turtles in Santa Barbara and Ventura counties. CIMWI’s jurisdiction includes 153 miles of coastline (from the San Luis Obispo/Santa Barbara County line south to the Ventura/Los Angeles County line).
Information provided by Channel Islands Marine & Wildlife Institute (CIMWI).
To report a stranded marine mammal that is sick, injured, malnourished, entangled, deceased or oiled in Santa Barbara County and Ventura County, call Channel Islands Marine & Wildlife Institute’s (CIMWI) Rescue Hotline (805) 567-1505.
To report a bird in distress in Santa Barbara and Ventura counties, call Santa Barbara Wildlife Care Network, (805) 681-1080.
For more information about domoic acid, see the NOAA’s Domoic Acid Fact Sheet
For more information on domoic acid and human health, visit California Department of Public Health’s site