Red Tides

Red tides occur all over the world but the farthest north they have been detected in Alaska is Cook Inlet. They are large blooms of toxin producing dinoflagellates that may color the water a deep red. The key point is the production of toxin. Red tides can actually produce other colorations of the tides, but not all colored tides are necessarily toxic. The toxin is taken in by filter feeding animals and stored in their flesh.


Red tides occur all over the world but the farthest north they have been detected in Alaska is Cook Inlet. They are large blooms of toxin producing dinoflagellates that may color the water a deep red. The key point is the production of toxin. Red tides can actually produce other colorations of the tides, but not all colored tides are necessarily toxic. The toxin is taken in by filter feeding animals and stored in their flesh. The effects of the toxin occur in the predators of these organisms. The only red tide that is known to have occurred this far north is the PSP, Paralytic Shellfish Poison, which is a toxin that disrupts nerve functions. There is significant commercial and sport harvesting of shellfish along the Kachemak Bay and Cook Inlet beaches. We propose a variety of monitoring methods. They include the monitoring of the medical facilities, periodic analysis of the shellfish, plankton tows, cyst analysis and designated cultures of mussels and oysters. In addition, personal use kits are also being investigated and may be available in the near future.

Causes of Red Tide

Red tide is a naturally occurring, higher than normal concentration of microscopic, single celled, photosynthetic algae. Some are capable of movement through the use of flagella while others drift with currents. These microscopic plants range in size from 1/1000 of a millimeter to two millimeters and float or swim in the upper 100 meters of the ocean.

Gonyaulax, Noctiluca and Alexandria are the three genera that produce a toxin that affects the central nervous system of some marine animals so that they’re paralyzed and can’t breathe. When red tide algae reproduce in dense concentrations or “blooms”, they are visible and are discolored patches of ocean water. They are often reddish but can be brown, yellow, green, or milky in color.

Alexandrium causes the red tides that are found in Alaska, which is larger than Gonyaulax. That is what Susan Saupe, oceanographer by trade said. Alexandrium occur in chains but are also quite mobile because of flagella as can be seen in fig.1. Harmful “algal bloom” is filtered from the water by shellfish such as clams, mussels, oysters, scallops or small fish.

Fig 1

Fig. 1 Alexandrium chain.

It’s almost impossible to say where red tide is because the blooms constantly expand, contract, and move around in response to the winds and tides. It’s important to realize that red tide is typically isolated patches that don’t blanket every stretch of beach. Over the last several decades, the United States has experienced an escalating and worrisome trend in the incidence of problems associated with harmful and toxic algae. Only a few regions were affected, but now virtually every coastal state is threatened in many cases over large geographic area and by more than one harmful or toxic species.

Fig 2

fig.2 The percentage of PSP incidence in North America in 1995

The graph above represents the percent of PSP in the East, West, and the North. The biotoxins can be transported by and though the air, causing severe eye, nose, and throat irritation.

Effects of Red Tides

Red tides have a deadly effect on sea life. Two really harmful effects can result from red tides. For one, it causes oxygen depletion of surface waters, which leads to mass mortality of larger invertebrates and fish. Secondly, shellfish that have ingested the poison are eaten in turn by other animals and will cause them to die. Scallops are not as harmful because the visceral organs where the toxin concentrates are not eaten. The toxic algae that cause red tides is eaten by fish and stored in the guts and intestinal tracts. A fish that is gutted in the usual manner is therefore ok to eat. The PSP is passed along to the predators of mussels, oysters and clams, though because they are eaten whole.

The effects of any of the red tide toxins, is increased with each consumer level. This is for two reasons. The toxins concentration is increased and the toxin molecule is changed to become more toxic. As an example, see the figure below.

Fig 3

fig. 3 Molecular transformations change the toxicity of the saxitoxin molecule. The diagram illustrates two common types of chemical transformations that occur when the saxitoxin is passed on from algae to shellfish.

Red tides kill hundreds of thousands of fish and mammals around the world. The humpback whale is another marine animal that has been greatly affected by red tides. Fourteen humpback whales were killed off the coast of Massachusetts in one month due to eating toxic mackerel. Humpback whales are also found in Alaska waters.

Florida manatees have also been killed. In 1996, 150 manatees died. This is extremely bad due to the fact that this animal is endangered. Stomach contents showed that the toxin entered through the food web and lung tissues also showed that direct contact with a toxic aerosol occurred when the animals broke surface to breath.

Fig 4

Fig.4 This is a picture of a humpback whale that washed up onto a Massachusetts beach after feeding in a red tide.

Fig 5

fig. 5 These are manatees that ingested red tide organisms in Florida.

In July of 2000, more than ninety sea lions were found dead and dying on beaches in California. Sixty of these sick sea lions were transported to nurse back to health, but not many were expected to live. Also affected are the sea birds that feed off the toxic fish. Exposure is not always initially deadly, but many birds die during high stress times such as migration.

It becomes evident that the red tide toxins reach all levels of an ecosystem. This model shows how PSP can travel through the food web and eventually reach humans. It shows that the toxin can be passed to humans by a number of paths.

Fig 6

fig. 6 This shows the pathways that toxins may take to effect all stages of a food web.

Ingestion of shellfish is the main way humans will get PSP. It will disrupt nerve function and results in paralysis (hence the name paralytic shellfish poisoning). Some other symptoms include narcosis, the development of sores, difficulty breathing, blurred vision, kidney and liver dysfunction, short-term memory loss, and cognitive impairment. These effects have reoccurred in victims up to six years after exposure. PSP can be very deadly in humans due to paralysis. There is no cure for this. Death usually occurs from asphyxiation, or respiratory paralysis. Even a person coming in contact with a toxic aerosol will have respiratory distress but most of the time when they leave the beach or get into an air-conditioned home it will go away. People swimming in contaminated waters will get a skin irritation. This is a sign that would be posted on the beach were red tides are occurring to warn off swimmers.

Fig 7

Fig. 7 Red tide warning sign.

Where Red Tides Occur

Red tides occur throughout the world, drastically affecting Scandinavian and Japanese fisheries, Caribbean and South Pacific reef fishes, and shell fishing along United States coasts. Most recently, it has been implicated in the deaths of hundreds of whales, dolphins, and manatees in North American waters.

This occurs where two water masses meet or where wind driven convection patterns, windrows, exist. This, in turn, causes water from the depths to rise bringing up rich nutrients. The current listing of places in Alaska, with an accompanying map, that have had occurrences of red tides are:

Constantine Harbor, Amchitka 
Cross Island 
Estrus Point, Hagemeister Strait 
Hagemeister Island (north end) 
Kivalina, Chukchi Sea 
Kodiak, Women’s Bay 
Kotzebue, Kotzebue Bay 
Massacre Bay, Attu Island 
Nikiski, Cook Inlet 
Nushagak Bay (Clark’s point) 
St. Michael 
Sweeper Cove, Adak Island 
Ugaiushak Island 

Fig 8

fig. 8 This Alaska map shows the occurrence of red tides.

Predictability of Red Tides

Red tides are not predictable, but under certain circumstances, the probability of a red tide can be projected within seven months. This would have to include information about the ocean’s sea surface temperature, the season, climates and currents. As can be seen in the graph above, May and June have the highest occurrence of PSP outbreaks. Other sources document 17 additional occurrences from 1995-97.

Fig 9

fig.9 red tide occurrences (Alaska’s Marine Resources: Paralytic Shellfish Poisoning, the Alaska Problem)

The Climatic Effects

Most cases of red tide seasonally occur. They tend to happen in the late summer an early autumn, although it may sometimes depend on the different temporal pattern in each region. This happens because at that time the weather is getting cooler causing winds to blow, which in turn, upset the settled ocean floor in a process called “upwelling”. This basically means that the nutrient rich water in the deeper parts of the ocean rises up to the surface. The upwelling also brings up the dormant cysts, which rest in the sediments on the sea floor. Because of the good temperature, salinity, and light conditions at the time of the upwelling, it is very easy for the cysts to germinate, thus is the first step on its way to a quickly multiplying harmful algae bloom.

Climatic changes greatly affect the frequency of occurrences because it takes cool winds and a cool climatic temperature for the upwelling to occur. If the waters are too cold, the germination may not be able to take place.

Current PSP Monitoring

The Alaska Department of Environmental Conservation, DEC, is currently monitoring red tides and PSP outbreaks in the Kachemak Bay and Cook Inlet region and is shown in fig. 9. The following are all accepted by the state of Alaska as certified shellfish beaches: Polly Creek-Crescent River, Jakolof Bay, Kasitsna Bay, Tutka Bay, Halibut Cove Lagoon, Chugachik Island, Sadie Cove, Peterson Bay, and Little Jakolof Bay. A uniform Paralytic Shellfish Poisoning, PSP, sampling plan will be implemented once an area has been certified by the Alaska DEC. Approved areas are those waters where water sampling and marine toxin shoreline sampling have taken place and that fecal material, pathogens, microorganisms, poisonous and toxic substances are not present in dangerous concentrations. These plans have been established so that a grower or harvester is aware of the sampling requirements over a three year period. This plan also contains provisions that must be completed prior to permission being granted for a reduction in monitoring. Presently, ADEC monitors the west side of Cook Inlet from Harriet Point to south of Crescent River. You can see from Figure 9 that this is the opposite side of Cook Inlet from Kachemak Bay. Razor clams are traditionally harvested from mid May to the end of August during any year. ADEC takes razor clam samples and analyzes the whole animal, which is a very conservative testing since the average person only eats the edible portions, i.e. the body, foot and the neck. Then, the only processor, Pacific Alaska Shellfish Company in Nikiski sends in the samples for analysis. Thus, from the period that the fishery starts in mid May to the end of August someone, either ADEC or the processor, sends in samples to be analyzed during the twice a month low tide series.

Fig 10

Fig.10 Map of Cook Inlet and Kachemak Bay.

ADEC also samples the area between Clam Gulch and Anchor Point from time to time on no regular schedule from May through August. This part of Cook Inlet is just north of Kachemak Bay and is regulated for sport harvesting only. Commercial digging is not allowed. This area has not gone through the full water testing and shoreline work to access potential pollution sources. ADEC doesn’t actively monitor this area because of lack of funding for such activity and they have no jurisdiction on regulating sport/recreational harvesting activities. Their current regulations only pertain to the commercial harvest of clams, for resale or profit.

Public Notification

The Public Information Office (PIO) in Juneau disseminates PSP outbreaks through ADEC’s notification system via a press release to the various radio stations, newspapers and television channels throughout the state. Also, other state agencies, such as the Department of Natural Resources, Department of Fish and Game, and the Department of Public Safety, Division of Fish and Wildlife are notified. PSP expert, Mike Ostasz, usually writes up the press report once the episode is confirmed to be PSP, and then he sends it to the PIO and awaits approval through his boss and the Director. Upon approval or modification of the press release, it is then released.

If someone is thought to have PSP, getting that patient to a medical facility is the best course of action to follow. If symptoms do occur, the first thing to do is induce vomiting. This can be done by sticking a finger down the throat, by drinking salt water, or by taking Syrup of Ipecac. However, vomiting should not be induced in a semi-conscious or unconscious victim. Treating for shock is done by placing the patient in a prone position, elevating the feet, and covering them with a blanket. Victims should not be given digitalis or alcohol, because these drugs may increase toxin absorption. Seeking medical attention as soon as possible is important since severe symptoms may occur rapidly. Mouth to mouth resuscitation must be administered if there is trouble breathing until medical personnel take over treatment.

There is no known antidote for the toxin. PSP is a neurotoxin that blocks movement of sodium through membranes of nerve cells. Without sodium transmission, nerve cells can’t function. This ultimately leads to the symptoms of PSP: numbness, paralysis, respiratory failure, and coma.

Program to Monitor the Kachemak Bay Ecosystem for Red Tides

Our proposal for monitoring the Kachemak Bay for red tides involves five areas. The first area to monitor will be any illness to humans that might be due to PSP. We will expect any doctor, hospital or medical facility to immediately notify the authorities. This is an after the fact method of monitoring, but easy to set up and important in case of the failure of the remaining methods.

The mollusk species that are potentially harvestable must also be monitored. There are various locations around the Bay that are used to harvest a variety of species. There are some beaches and bays that are being used for commercial operations but there are also many small but rich beaches used for domestic and sport use. In those designated areas, sampling of indicator species maybe carried out. The most important species is the mussel. The mussels are the first species that become infested with PSP, but they hold their toxicity for a relatively short period of time. The butter clams hold their poisons the longest. They have been known to remain toxic for up to two years after a red tide has occurred. The razor clams are a species that lie in between. They do not become toxic as fast as mussels but do not stay polluted as long as the butter clams.

We also propose to set up vertical mussel and oyster cultures which could be a part of a local commercial operation which are currently operating in several of the side bays of Kachemak Bay. They grow on vertical columns suspended in the tidal waters. The middle portion of these columns would have the greater chance of picking up PSP, due to the fact that plankton migrate to the surface for daylight and back down at night. Therefore, the middle of the column will be exposed twice as long to any potential PSP carrying algae. Random sampling of these middle organisms will give us a first indication of a PSP outbreak.

Planktonic tows can also be done every so often and is considered our third level of monitoring. According to an FDA expert on Toxicology(Hall), this is a viable monitoring option. This will require people to be trained to use field scopes to analyze and identify the organisms. This assessment will also be done in specific locations, as well as in conjunction with sightings of coloration. To date, all sightings of tides of coloration have proven to be false alarms in Kachemak Bay. (Every sample taken has been caused by another nontoxic species.) An interesting point of observation is that all Kachemak Bay tidal blooms have originated in Jakalof Bay, as seen in fig11.

Our fourth level of monitoring is in the area of analyzing algal cysts. Some of the algae in a typical population will become a cyst as seen in fig. 10. A cyst is a hardened spore that will lie dormant in the very top of the sediment until upwelling currents bring them to the surface and conditions are ideal for growth. We feel the potential for advance PSP warning may be possible if the sediments are skimmed and analyzed periodically at least during the seasons that PSP is most likely to occur.

Another area that we feel that needs to be addressed is personal medical kits. This is not environmental monitoring, but might increase safety for the general public. A company in Nova Scotia is currently doing research in this area. The company is developing a personal PSP detection kit. Developer Ray Roberts describes the MIST Alert rapid test kit as being similar to a home pregnancy test. “Basically, we have developed a rapid test kit for PSP which is much like a home pregnancy kit. The test kit gives results in about ten minutes and is extremely easy to use. Applications of the kits are as a harvest management tool to know when it is safe to harvest shellfish, or as a quality control tool in shellfish processing plants. It can also be used in government regulatory labs as an initial screen for PSP. Our test has the potential to substantially reduce the number of live mice used for testing for PSP, which is the current testing method “(Roberts). The company currently has the trial ongoing with the test kit in Alaska, Norway, Scotland, the United States, Canada and New Zealand. The kits are commercially available now at a cost of twenty US dollars per test. Personal detection kits are not yet available but the company is currently doing testing work in Kodiak and other parts of the state.

Fig 11

Fig. 11. the life cycle of Alexandrium which shows the cyst stage.

Fig 12

Fig. 12 Kachemak Bay map



1 person’s salary(seasonal position of 6 months/year, G5)



vertical culture sampling; (supplies & equipment)

$ 2,000


plankton tow; (supplies & equipment)

$ 2,000


cyst analysis; (training, equipment)

$ 3,000


PSP detection kits; (100 kits at $20 each)

$ 2,000


Medical facilities monitoring;

$ 0


Incidentals; office supplies etc.

$ 1,000




Budget description:

The largest budget is the salary of a trained professional staff of one. We believe that this person should be attached to the Kachemak Bay National Estuarine Research Reserve (NERR) facility because it is located in Homer on Kachemak Bay. This position could also be attached to the Alaska Department of Environmental Conservation (ADEC) or the Alaska Department of Fish & Game (ADF&G). ADEC makes the most sense since it is currently charged to monitor all the commercial claming beaches and would also be a logical overseer.

The salary will follow ADF&G’s scale for seasonal employees at a G5 level. Since this person will be attached to an existing facility, much of the more expensive equipment such as skiffs will be shared. The major equipment needed will be plankton nets, microscopes, and gas.


Money for this project will most likely need to come from the government and be mandated by the legislature to be part of the NERR or ADEC. It is therefore important to impress the importance of this matter to the legislators to allocate and release these funds. The only way to accomplish this is to educate them to the growing trend in both the number of occurrences of PSP outbreaks and the increasing use of the area beaches by tourists and locals. It is possible that the fishing license fees be increased to pay for this program.

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Red Tides

Red tides occur all over the world but the farthest north they have been detected in Alaska is Cook Inlet. They are large blooms of toxin producing dinoflagellates that may color the water a deep red. The key point is the production of toxin. Red tides can actually produce other colorations of the tides, but not all colored tides are necessarily toxic. The toxin is taken in by filter feeding animals and stored in their flesh.

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