Domoic acid toxicity has been known to affect marine life, in particular here, on the US west coast. We’ve seen lots of evidence for marine mammals being affected.

Greetings, attentive viewers, to this week’s episode of Planet Earth: Our Loving Home, where we’ll present part one of our two-part series on the harmful algal blooms, known as HABs, that are injuring coastal ecosystems around the globe, with a focus on the threat to marine animals caused by domoic acid.

For expert insight on this issue we’ll hear from Dr. Vera Trainer, a supervisory oceanographer at the National Oceanic and Atmospheric Administration’s Northwest Fisheries Science Center in Seattle, Washington, USA who has conducted HAB research for many years and Dr. Bill Cochlan, a biological oceanographer at the Romberg Tiburon Center for Environmental Studies, a part of the San Francisco State University system, in Tiburon, California, USA.

Dr. Cochlan has also done extensive work on the issue of harmful algal blooms. The tiny marine organisms known as phytoplankton play a pivotal role in global carbon circulation, being responsible for 50% of all photosynthetic activity on Earth, and emitting vast amounts of oxygen into the atmosphere.

However, some types of phytoplankton cause HABs, which wreak havoc in aquatic environments. Approximately 300 species of microalgae are known to form algae blooms. And almost a fourth of these species can generate toxins. As a result of toxin transfer through the food chain, HABs may debilitate or kill animals near or at the top of the chain.

An algae bloom is much like a bloom of flowers, for example, that you would see in a field. It’s a high number of cells that presents in the ocean. Usually when scientists use the term “bloom,” they refer to or they mean approximately a million cells per liter. It’s high enough numbers to actually be able to see in the water.

It depends on the species, but some algae can double their biomass every 12 hours. But generally, once a day is a standard rate for most phytoplankton species.

Harmful algal blooms are often called “red tide” in the media because their size may become so great that the waters in which they occur appear red in color. But the color of the algae’s pigment varies.

Scientists do prefer (the term) “harmful algal bloom” to “red tide.” These blooms of organisms are not always red. They're lots of colors; all the colors of leaves are those represented in marine algae as well, so they can be brown, they can be green, and they can be yellowish.

HABs can occur in both freshwater and marine environments regardless of water temperature and salinity and affect most of the world’s coastal areas. The domoic acid- producing algae called Pseudo-nitzchia is not isolated to any one area, but rather it is found across the globe.

What we do find is now a worldwide occurrence. The cells that produce domoic acid do well in cold water as well as warm water. They have a high tolerance to salinity, from very, very high salinity waters to low salinity waters. They’re all marine, but they can do well in low salinity so in estuarine environments as well.

But they tend to be most abundant in, as I mentioned before, Eastern boundary currents. And Eastern boundary currents are the ones where we have upwelling of deep water that comes to the surface. One of the hotspots for this sort of activity is the west coast of North America, along California, Oregon and Washington state.

We also have it in South Africa, that’s also the Benguela Current, which is another Eastern boundary current. They do find it in Europe, they found in Japan and Asia and in South America. But right here off Monterey Bay (USA), off the Washington State (USA) coast, these are considered very, very toxic zones.

Pseudo-nitzschia averages around one doubling (in population) a day.

Because it is a diatom, it makes it one of a special group of plankton. In that they don’t have an organic cell wall. Instead they have a cell wall that’s made of silica or silicon. Because of that, it doesn’t require as much energy to make that cell wall. So diatoms in general are a little more ecologically efficient, or it may make them more successful compared to other cells.

Domoic acid bio-accumulates, meaning it increases in toxicity as it is passed up along the food chain. It starts with small, plankton-eating fish like sardines and anchovies and shellfish and at the end of the cycle can fatally poison larger species.

Domoic acid is a compound that is toxic to vertebrates. It is toxic to humans, marine mammals, and marine birds. It is a compound that is very close in structure to our amino acids. So amino acids are the building blocks of proteins.

We know that Pseudo-nitzschia makes the toxin; the toxin is then incorporated either into the fish or the shellfish.

Once the fish all die and eventually sink to the bottom, there still could be a transfer of that domoic acid to the benthos, to the organisms on the bottom, the positive feeders and such. So an important thing when you study marine biology and marine ecology is understanding these linkages. From the very, very small microscopic phytoplankton to these large multi-cellular whales, there are a lot of very direct linkages.

And with respect to these diatoms, generally you don't find an ill effect if the series of linkages is more than three. There's usually just two linkages from the phytoplankton to the planktivorous fish or shellfish that eat them by filter feeding, to the next step. And that next step, that's where the animals or birds are impacted. So it's a very short chain.

In April 2011, dolphins washed ashore at various points along the Southern California, USA coastline. Some were seen experiencing seizures before dying, while others had already died before reaching land. Domoic acid is suspected as the cause or one of the factors in the deaths.

And more recently, dolphins have been affected by domoic acid poisoning. And we have to be careful in saying that domoic acid is a cause of death or the sole cause of poisoning because it could be possible that a number of neurotoxins are acting together. But we know for sure that domoic acid is measured in the urine of these animals and it is surely impacting their health.

In March 2011, in the same region, six sea lions were found dead and 175 tons of sardines all perished at once in Redondo Beach’s King Harbor. Again in both cases it is thought domoic acid played a role in harming the wildlife.

One of the worst cases of poisoning in Southern California was a period between 2002 and 2003 when over 1,000 sea lions and 50 dolphins succumbed to domoic acid. Toxin-induced abnormal behavior in marine animals has been observed for many years. For instance, some sea lions have shown head waving, bulging eyes, mucus discharges from the mouth, disorientation and seizures. Such symptoms often precede the short-term memory loss or death of the animals.

This image here, we have a California sea lion. Now we see a section of their brain and this is one that’s gone through an autopsy. And then here if we do a blow up of the lower part of the brain here, we can see the hippocampus. And on this first image here, this shows a healthy, normal brain of a California sea lion and the hippocampus is totally intact and presumably it would have been functioning normally in the healthy growing animal.

But then when it’s exposed to domoic acid, and this is from an animal that succumbed to domoic acid poisoning, you see the hippocampus has been totally degenerated. So it no longer can really function as an effective organ in the brain. The hippocampus is largely responsible for memory in mammals and if the hippocampus isn’t functional, the memory capabilities of an animal are highly impaired.

In 1991, one of the first incidences of domoic acid poisoning occurred on the outer Washington (USA) coast. In Monterey Bay (USA) there were seabird mortalities being observed. These seabirds were flying erratically, they were hitting windows, and there were large numbers of them. It was not understood exactly what was happening, but through scientific research, and further study, it was then determined the birds were feeding on Pseudo-nitzschia, or were feeding on the fish that were feeding on Pseudo-nitzschia, and they became poisoned.

I think even more recently we’ve noted that sea lions and sea otters are affected by domoic acid toxicity. Sea lions have even been so disoriented that they’ve ended up high on beaches; they’re resting on police cars, they are completely disoriented, not knowing where they are. A typical symptom of this poisoning is this head-bobbing motion, so they’re having severe neurological damage.

Humans may experience domoic acid poisoning through consumption of marine animals and the results can range from gastrointestinal problems to death.

We’ve seen that even humans have been impacted by DA (domoic acid), that they lose their short-term memory. And some even have long-term memory losses. So it’s quite an issue here. Now, four elderly people died in Prince Edward Island (Canada) in 1987. And there’s been many people that have been ill in the United States, on the west coast of the Pacific (Ocean), and on the Atlantic (Ocean seaboard).

There's an example of a physics professor who was sickened due to eating mussels in the Prince Edward Island event in 1987. He can teach his physics classes but he can't remember if he ate breakfast or where he parked his car. So it can have severe consequences in people.

We sincerely thank you, Drs. Vera Trainer and Bill Cochlan, for taking time from your busy schedules to speak with us about harmful algal blooms and their severe impact on our vulnerable marine ecosystems.

For more details on the experts featured today, please visit the following websites:
Dr. Bill Cochlan
Dr. Vera Trainer

Green viewers, thank you for joining us on our program. Please watch Planet Earth: Our Loving Home again next Wednesday for the conclusion of our two-part series when we will examine solutions to protect marine animals from harmful algal blooms. May the guidance of Providence always be with us.