Harmful algal blooms, also known as "H --A --Bs" or "HABs", are caused by tiny plants in the ocean, known as phytoplankton. The term "phytoplankton" comes from the word "phyto", meaning "plant", and the word "plankton", meaning "drifter". There are more than 10,000 known species of oceanic phytoplankton, but only about 300 are known to cause blooms. Blooms occur when one species, of the many living in the water together, rapidly increases in number within a small region.

HABs are often seasonal events, and may be caused by many different factors ranging from an excess of nutrients, slow-moving water, or winds and currents causing physical aggregation of cells. Unfortunately, HABs can often cause damage to coastal ecosystems and economies. Bloom-forming algae not only discolor water, they can create dead zones and stress organisms such as shellfish, corals, and seagrasses. The most harmful of HAB species produce toxins that can kill fish and mammals.

The toxins produced by HAB species include brevetoxins, which cause neurotoxic shellfish poisoning, saxitoxins, which cause paralytic shellfish poisoning, domoic acid, which causes amnesiac shellfish poisoning, and ciguatoxins, which cause ciguatera fish poisoning. The most serious route of exposure for humans is when we eat shellfish during blooms. Shellfish, such as oysters or clams, ingest toxic algae cells by filter feeding and so concentrate the toxin inside their tissues. When humans eat these shellfish, they get a large dose of toxin. Unfortunately, cooking shellfish will not eliminate toxins. Symptoms can include nausea, vomiting, paralysis, amnesia, neurological effects, and sometimes death, depending on the toxin. For this reason, monitoring for early warning of HABs and timely closures of shellfish harvesting are essential to prevent human illness.

Script Author: McKensie Daugherty

Contributing Professor: Dr. Lisa Campbell

Do you see that growing red stain in the water? It’s not a shark attack, it’s a red tide. Red tides occur almost annually on the west coast of Florida in the Gulf of Mexico, and due to currents like the Gulf Stream it also can be carried into the Atlantic Ocean. Red tides are caused by an algal species known as Karenia brevis. But why is that important? This alga produces toxins that can lead to huge fish and animal kills, and can also make people very sick by causing intestinal distress, respiratory issues, and skin irritations. When Karenia brevis accumulates, it causes a discoloration in the water, which is where it gets the name ‘red tide’. This discoloration is the main evidence to suggest a bloom is in the area. Dead fish washed up on the beach is also a sign.

Karenia brevis produces neurotoxins called brevetoxins that attack the central nervous system of fish and accumulate in shellfish tissues, which results in neurotoxic shellfish poisoning when we eat contaminated shellfish. At the beach, toxins in the air can also make your eyes sting. The algae are not only harmful to animals and humans, but also threaten the economy. When these blooms occur, coastal economies are impacted because shellfish harvesters can’t harvest shellfish. They can also lead to people not being able to safely go to the beach which leads to a major decrease in revenue for beach communities. So how do we fix this? Monitoring of coastal waters is crucial, especially in the late summer to early fall when Karenia blooms typically occur. Keep listening to our series learn more about monitoring for HABs and watch out for that red tide!

Script Author: Megan Borm

Contributing Professor: Dr. Lisa Campbell

Harmful algal blooms, also known as "red tides", in the Gulf of Mexico are predominantly caused by the algae species Karenia brevis. Blooms of this toxin-producing alga occur almost annually in Florida, but less frequently along the Texas coast. A rapid increase in the number of K. brevis cells in a region can cause discolored water, widespread death of fish, and can impact human health. The toxins produced by Karenia brevis can be released into the air causing breathing difficulty or they can be accumulated in filter-feeding shellfish causing neurotoxic shellfish poisoning in humans who consume the contaminated shellfish. Therefore, it is very important that fisheries and beachgoers are properly warned of these blooms, so the prediction of HABs for the Texas coast is a critical subject of scientific research.

Using historical data from the past 20 years, researchers found that measurements of the intensity and duration of along-shore winds were correlated with occurrences of Karenia blooms. Specifically, the along-shore winds create what is known as downwelling conditions. Downwelling occurs when surface waters converge. In this case, convergence occurs when surface water is moved towards the coast and this pile-up pushes the surface water downwards. The convergence and consequent downwelling at the coast concentrates Karenia cells. The correlation of specific wind conditions and bloom occurrences can allow researchers to predict a Karenia bloom.

Monitoring and predication of HABs is not only important to protect human health, the effects of HABs can also cause many economic problems if shellfish harvesting is closed and by negatively impacting local tourism. Toxic HABs blooms can shut down beaches for discolored water or for smelly piles of dead fish and this can ruin a tourism-driven economy for weeks to months at a time.

Script Author: McKensie Daugherty

Contributing Professor: Dr. Lisa Campbell

Dinophysis is an emerging threat to human health in coastal communities world-wide as the cause of Diarrhetic Shellfish Poisoning, or DSP. In the Gulf of Mexico, Dinophysis ovum is the toxic DSP-causing species. As its name describes, it is an oval-shaped dinoflagellate that produces toxins that can be harmful to humans. Dinophysis ovum can be found in the Gulf of Mexico along the Texas coast. The blooms occur most frequently in February, but the timing of blooms seems to be related to water temperature. If there is a warmer spring (water temperature exceeds 15 degrees Celsius) the bloom may start in February, but if warming is delayed, the bloom will occur later in the spring. Higher cell abundances have been noted on incoming tides, which suggests blooms may start offshore.

The biggest impact on human health from Dinophysis blooms is DSP, which can cause gastrointestinal distress. In the environment, contamination of shellfish can occur in areas where Dinophysis blooms. Unfortunately, once a bloom starts there is nothing that can be done to protect humans other than to close down shellfish harvesting. However, with continuous monitoring of cell counts in the regions where these algae historically bloom and cause DSP, we can detect the blooms as they develop and before they reach dangerous levels. We will report on monitoring efforts in Texas later in this series, but with continuous monitoring it is possible to prevent people from getting sick from eating contaminated shellfish.

Script Author: Corinne Cox

Contributing Professor: Dr. Lisa Campbell

The most toxic of all the HAB species are dinoflagellates in the genus Alexandrium. Of the 34 species in this genus, 16 produce paralytic shellfish toxins. One of these, Alexandrium catenella, typically occurs during summer in the North Pacific, South Pacific and South Atlantic, so it affects the US, Canada, Chile, and South Africa. Cells often occur in chains, so have been described as “small trains” when viewed under a microscope.

One of the most significant impacts of Alexandrium catenella blooms is the frequent shutdown of shellfish harvesting, which is done to avoid the lethal toxin known as Saxitoxin. Alexandrium catenella produces this toxin and when shellfish feed on these algae the toxin is not broken down and builds up in their tissues via a process known as bio-accumulation. Unfortunately, saxitoxin doesn’t cause any visible changes to shellfish and it isn’t neutralized by cooking. Most people won’t realize they’ve even eaten contaminated shellfish until they begin to feel the symptoms of what doctors call “Paralytic Shellfish Poisoning,” or PSP for short. Early symptoms of PSP include tingling of the lips and fingers which progresses to a loss of movement in the limbs and difficulty breathing. In severe cases PSP can lead to respiratory paralysis and death. Thankfully, deaths from PSP are rare. Fisheries monitor for PSP to ensure that shellfish are not harvested until they’ve had time for the dangerous toxins to pass through their system.

Fertilizer runoff can cause a greater chance of Alexandrium occurrences. Additionally, based on predictive models, it is hypothesized that climate change will result in increased blooms of Alexandrium catenella. But even now, efforts are being made by scientists to find ways to mitigate blooms of Alexandrium catenella when they occur, with the goal of protecting shellfish harvesting from PSP.

For more information about how scientists are mitigating the effects of Alexandrium catenella using seaweeds, click the link here: https://pubmed.ncbi.nlm.nih.gov/34303515/

For more information on the morphological description of this organism, click the link here: https://www.eoas.ubc.ca/research/phytoplankton/dinoflagellates/alexandrium/a_catenella.html

Script Author: William Nickerson

Contributing Professor: Dr. Lisa Campbell

Food poisoning is always an unpleasant surprise after meals, and unluckily for the Irish, shellfish and crabs seem to be a common cause. What’s to blame for this?? An unwanted pest that has sprung up all along the Northern European coasts, known as Amphidoma languida. When placed under a microscope, scientists can recognize this dinoflagellate species by its brown coloration and oval shape. It also has interlocking plates resembling the mussels that like to gobble it up. When consumed by these filter-feeding shellfish, the toxins are stored in their meat. If eaten, expect diarrhea, nausea, vomiting, and abdominal cramps to give you a bad time, which can lead to a date night spent in the bathroom.

Amphidoma languida is similar to a closely related dinoflagellate, Azadinium, but it stands out with its unique toxin profile. Using quantitative PCR, which amplifies the amount of DNA within the cell, a very sensitive and specific quantitative method has been developed. Using this method, scientists can identify this species among the other hordes of phytoplankton in the area. Once found, most areas will be blocked off from harvesting to prevent human consumption. However, it’s probably best to be aware of conditions before eating that freshly caught seafood special at the pub when you’re on vacation.

Additional Information:

Azaspiracid toxins (AZAs) are the most recently discovered group of lipophilic marine biotoxins of microalgal origin that accumulate in shellfish and are responsible for human shellfish poisoning. Originally, this toxin was described from the dinoflagellate Azadinium, but more recently it was reported in the related species Amphidoma languida. A. languida is smaller than most other Amphidoma species and is named for its apparent slow, “languid” swimming.

This toxin is mainly found bioaccumulated in blue mussels and scallops, but other organisms include oyster, razor clam, cockles and brown crab. Azaspiracid has a global distribution and is tested for and regulated in Europe but not yet in North America. In the United States, Azadinium and azaspiracids have been detected in Puget Sound, WA, but so far Amphidoma languida has not been detected.

For more information see:

https://hab.whoi.edu/impacts/impacts-human-health/azp/

Script Author: Haleigh Blume

Contributing Professor: Dr. Lisa Campbell

You’ve heard of red tides, but what about Mahogany tides? A common toxic phytoplankton species in coastal environments is Prorocentrum cordatum. This species is widely distributed across tropical and subtropical regions and blooms are most commonly recognized by the mahogany water color produced when Prorocentrum cordatum cells are found in high concentrations. Prorocentrum cordatum can adapt to a wide range of salinities and temperatures, which has allowed its distribution to expand over the past several decades. The toxins that Prorocentrum produces are linked to diarrhetic shellfish poisoning, or DSP, in humans. Additionally, these blooms have been known to cause mass fish and shellfish aquaculture mortalities due to the low dissolved oxygen levels the blooms leave behind once the phytoplankton die.

While there is no good way to stop the blooms, the best way to mitigate the effects on humans is early detection. Coastal monitoring programs are essential to detect when the levels of toxic phytoplankton increase and to provide local health departments notifications of increasing concentrations. This enables areas affected by Prorocentrum cordatum blooms to avoid cases of diarrhetic shellfish poisoning.

Script Author: Kylie Powers

Contributing Professor: Dr. Lisa Campbell

No, they’re not the newest Marvel villain; Gonyaulax spinifera are dinoflagellates, single celled organisms that have two flagella that help them move around. They range in size from 25 to 175 microns in diameter – about the same diameter as a human hair. Cells in this genus are found world-wide—including the Gulf of Mexico—and from polar to tropical waters, marine to brackish, and even in some freshwater lakes of Europe! Dinoflagellates in the genus Gonyaulax commonly cause red tides when they bloom. Red tides become a very dangerous area for sea life and humans because some species produce paralytic shellfish poisons, or PSP. Gonyaulax spinifera, however, produces a different toxin: yessotoxin. Although Yessotoxin can produce similar symptoms to PSP in mice, there is no direct link between yessotoxins and toxicity in humans. In mice, yessotoxin appears to cause damage to heart muscle cells, so to be safe many countries do monitor shellfish for contamination with yessotoxins to protect humans from potential health risks.

For more information on Gonyaulax Spinifera see:

https://www.algaebase.org/search/species/detail/?species_id=52325

http://oceandatacenter.ucsc.edu/PhytoGallery/Dinoflagellates/gonyaulax.html

https://eol.org/pages/901308

Script Author: Christopher Crain

Contributing Professor: Dr. Lisa Campbell

More than 50,000 people suffer from ciguatera annually, making it the most common algal-induced seafood illness. Ciguatera is caused by Gambierdiscus toxicus, a photosynthetic marine alga that is found in tropical waters, including the Gulf of Mexico. Ciguatoxin, the toxin that causes ciguatera, undergoes biomagnification through the food web. Because the toxin isn’t metabolized, by the time large fish, such as black grouper or blackfin snapper, are eaten by humans, the concentration of ciguatoxin has increased greatly and can affect neurological, digestive, and muscular systems. Symptoms of ciguatera poisoning can include nausea, vomiting, diarrhea, and stomach pain. These symptoms usually appear within 6 hours of eating contaminated fish and go away after a few days; but in some cases symptoms can last weeks or years!

Ciguatoxin poisoning has been known for centuries in tropical regions but is now an increasing risk worldwide due to international trade of fishery products and the expansion of the geographic ranges of the causative dinoflagellates. In the US, ciguatoxin is monitored by the National Centers for Coastal Ocean Science, which is a government organization under the National Oceanographic and Atmospheric Administration, or NOAA. To protect human health, ciguatoxins in fish can now be detected 20 times faster than previous methods—an improvement from two and a half days to just three hours using a technique known as fluorescent receptor binding assays.

For more information see:

How many people suffer from ciguatera?

https://coastalscience.noaa.gov/news/noaa-improves-monitoring-ciguatera-fish/

Improvement in ciguatoxin detection.

https://www.cdc.gov/nceh/ciguatera/

What types of fish carry ciguatoxins?

https://hab.whoi.edu/impacts/impacts-human-health/human-health-ciguatera-poisoning/

Script Author: Alec Krueger

Contributing Professor: Dr. Lisa Campbell

Coolia is a warm ocean-loving armored, marine, benthic dinoflagellate that is a microscopically small troublemaker. It can be planktonic--free floating in the water, benthic--lives in the sediments on the ocean floor, or epiphytic--able to grow on other plants. If it were big enough to see with the naked eye, it would look like a walnut. Its structure is almost identical to a walnut’s: the two halves of the shell are held together, but there are a few major cracks to separate the shields. Yet, sadly, Coolia does not taste like a walnut; in fact, it’s toxic to marine organisms and to humans! Despite their size, these dinoflagellates pack a punch. When all of them gather together, it can cause serious havoc on organisms, let alone ecosystems.

Coolia can be found all over the world! These single-celled organisms love the coastal shallow waters, whether it is in the Mediterranean Sea, the Atlantic, or the Pacific Ocean. Usually, as the temperature goes up, so does the Coolia population. Another condition that favors Coolia is eutrophication - when lots of nutrients build up, producing dense growths of plant life, but can also reduce the oxygen level in that area when plant life dies and decays. Coolia is a contributor to a sickness called Ciguatera Fish Poisoning, or CFP, which threatens young marine invertebrates and humans. The side effects of CFP in humans can show up as soon as 30 minutes after consumption of contaminated fish. Symptoms include tingling, nausea, diarrhea, skin rash, chills, and at worst neurological and respiratory issues or death. It’s safe to say, Coolia isn’t cool at all.

For more information see:

National Research Council (US) Committee on the Ocean's Role in Human Health.

Washington (DC): National Academies Press (US); 1999

https://www.ncbi.nlm.nih.gov/books/NBK230692/

Script Author: Veronica Burgos

Contributing Professor: Dr. Lisa Campbell

Today we're talking about a harmful golden alga known as Chattonella that has toxic effects in fish. There are four taxonomically accepted toxic species whose size range between 20 and 50 micrometers, each with its own two swimming and trailing flagella. These cells contain a lovely golden-brown chloroplast that doesn't appear so beautiful when a bloom occurs – leaving behind yellow water and dead fish. Scientists have not determined why these blooms are toxic but have narrowed it down to an unstable molecule that contains oxygen, known as an oxygen radical. Oxygen radicals have been studied as a significant link to fish mortality due to their ability to attach to a fish's gills.

Chattonella is tolerant to various temperatures, can migrate vertically to find optimal salinity and nutrient conditions, and is mixotrophic, meaning they can rely on both photosynthesis and consuming organic compounds or other organisms. Chattonella are found worldwide in coastal and bay environments in a wide range of salinities with rich organic materials. Fish mortality occurs when cell density exceeds one million cells per Liter. For now, the best way to combat them is to reduce nutrient loads of organic and inorganic matter into the ecosystem. Not only would reducing nutrients help fight fish-killing Chattonella, but also other harmful algal species.

Additional Information:

While the main toxin cited for Chattonella is the oxygen radical or reactive oxygen species (ROS), other toxins such as hemolytic, hemagglutinating, and molecules similar to brevetoxins have also been linked to fish morality and toxic blooms from Chattonella species.

Chattonella blooms could have direct impact on human health if shellfish contaminated with the Chattonella biotoxins at high levels are consumed. Symptoms would include gastrointestinal illness.

Effects on the environment, such as fish morality and dead zones can cause extreme economic loss since many of the finfish and shellfish affected are used for wild harvests and aquaculture. Economic losses in the past include the US loss of 0.5 billion dollars in 1972.

Information on toxicity

https://www.vims.edu/bayinfo/habs/guide/chattonella.php

This link provides further insight into phylogeny and morphologies into the Chattonella species, for information regarding physical and behavioral characteristics.

https://www.tandfonline.com/doi/full/10.1080/09670262.2013.771412

This link highlights the toxic effects that Chattonella can have on fish in the environment and provides an understanding of the fish-killing compounds in toxic blooms of Chattonella.

https://www.sciencedirect.com/topics/immunology-and-microbiology/chattonella

Script Author: Brittney Breazeale

Contributing Professor: Dr. Lisa Campbell

Inhabiting waters all over the world is a species with a 100% mortality rate for its victims. Polykrikos hartmannii is one of the most wide-ranged dinoflagellates in the ocean. However, very little is known about it. In fact, it was not until 2013 that the first bloom, or uncontrolled exponential growth, was quantitatively recorded. While it does have a 100% mortality rate, you can rest easy as the only recorded victims are juvenile Sheepshead minnows.

The lethal weapon used to kill the minnows, is believed to be a toxin released through the pores of Polykrikos hartmannii. This organism is an unarmoured dinoflagellate with a cylindrical body meaning its pores are directly exposed to the water allowing for quick release of toxins. Often found in pairs, forming a pseudo colony, these organisms are brown in color due to the high levels of pigmentation in the cells. They often form cysts in order to survive until conditions are favorable enough to facilitate a bloom.

During warmer periods, and with the right mixture of nitrogen and specific B vitamins, a bloom may occur as was seen in New York’s Forge River during the summers of 2008-2010. Yet, even in these favorable conditions, blooms last a short time. Given the lack of information and weak impact of these algal blooms, little needs to be done to prevent such occurrences. Rather, studies should continue to better understand the organism that is Polykrikos hartmannii.

Script Author: Ryan Petre

Contributing Professor: Dr. Lisa Campbell

We have been discussing harmful algal blooms, or HABs, over the past several weeks. In this final segment we will discuss how scientists study these blooms and provide early warning of HABs in the Gulf of Mexico. Gathering data on algal blooms requires a multifaceted approach. Satellite imagery can provide data on water temperature, winds, currents, and phytoplankton biomass (using measurements of reflected light) at the areas where blooms are occurring. Buoys, or manually collected samples, can provide similar data and, in addition, seawater properties (such as salinity and nutrients). Over time, by collecting detailed information on the conditions during a HAB event, scientists can begin to hypothesize about the conditions necessary to cause and sustain a bloom. Of course, conditions will differ for each of the different HAB species we’ve discussed, so this is a work in progress.

Until recently, monitoring of phytoplankton was limited to water samples collected periodically at various locations for manual identification and counting by microscopy. This is extremely labor-intensive. We now have an automated technique using an underwater microscope system, the Imaging-Flow Cytobot. The Cytobot takes a small sample of water and uses a camera to take pictures of each phytoplankton cell. Computer software then automatically classifies each image. This technology is not only incredibly fast, but also allows continuous operation of the automated sampling and identification process, allowing more samples to be examined each day. Texas A&M University currently operates a network of Imaging FlowCytobots in Port Aransas, at the University of Texas Marine Science Institute, and at the Freeport Coast Guard station at Surfside Beach, Texas.

When a toxic algal species is identified and the number counted signals a developing bloom, an email is automatically sent to researchers at Texas A&M University, the Texas Parks and Wildlife Department, and the Texas Department of State Health Services. This provides an early warning to state managers and they can begin testing shellfish for toxins. Overall, the IFCB has provided successful early warning for 8 HAB events since 2007 and no human illnesses from toxic shellfish have been reported.

Additional Information:

Imaging FlowCytobot is produced by McLane Research Laboratories, Inc.

https://mclanelabs.com/imaging-flowcytobot/

Real time data in the Gulf of Mexico:

https://sites.google.com/tamu.edu/phytolab/toast

Gulf of Mexico HAB primer

https://gcoos.org/wp-content/uploads/2020/01/final_9_16_13_HabPrimer.pdf

Script Author: Dr. Lisa Campbell