Bloom of Discoveries


In the early 1500s, Spanish conquistador Álvar Núñez Cabeza de Vaca observed that indigenous people on the modern-day Texas coast would seasonally suspend shellfish harvest in response to widespread fish deaths. In 1648, a Franciscan monk in Mexico wrote of a ship from Spain that “encountered a mountain of dead fish near the coast.”

These accounts are some of the earliest reports in North America of harmful algal blooms, or HABs — an increasing occurrence in Maine and coastlines around the world.

HABs pose serious risk to wildlife and waterfront communities, forcing the closure of beaches and fisheries each year. However, scientists do not fully understand what causes harmful algae species to quickly grow in great abundance or what causes such blooms to end.

Bigelow Laboratory researchers are working to answer these fundamental questions about HABs and determine the best ways to minimize their negative consequences. Teams are studying when and why the blooms occur and how science can empower government and community efforts to keep people and seafood safe.

“Harmful blooms are not just caused by one species and don’t just cause one type of problem, which makes them really complicated to understand and address,” said Senior Research Scientist Rachel Sipler, who has studied HABs from the Arctic to the Gulf of Mexico. “A HAB is any algal bloom that causes a negative impact, and there are many ways they can do that.”

Some HAB species generate toxins. Some choke out competing organisms by using up oxygen. Others simply become problematically prolific — covering coastal surfaces, blocking light from marine organisms, and driving people from beaches. They can be found in oceans from pole to pole, and cyanobacteria cause similar events in lakes that can sicken people and kill pets.

Harmful algae species can exist in all bodies of water, but there is no one set of conditions that cause them to rapidly multiply to the point they are a problem. However, scientists believe increasing temperatures and nutrient pollution are key factors in their expanding in influence.

“There’s generally at least one potentially harmful species of algae in every liter of seawater,” Sipler said. “However, we don’t understand all the reasons that cause good algae to go bad. Sometimes, a HAB species doesn’t produce a toxin and has no negative impact on the environment. Other times, that same species can be really toxic even in low concentrations.”

Building Knowledge

As HABs expand, there is increasing necessity to identify the species and understand the conditions that cause them to form blooms. One foundational part of building this knowledge is monitoring when and where they appear.

Bigelow Laboratory hosts specialists from across the country each summer for a weeklong course on how to identify and analyze harmful algae using microscopes. Participants include researchers as well as government scientists responsible for advising when to shut down an area due to a HAB.

“We train others to better understand the spread of harmful algae species,” Senior Research Scientist Mike Lomas said. “We know certain species are harmful. While they may not be producing toxins at the moment, knowing they are present is a big step toward preventing harm.”

Microscopy remains the primary method for monitoring HABs, but emerging DNA-based tools are providing promising new avenues for understanding and managing harmful algae.

Senior Research Scientist Pete Countway is part of the $20 million “Maine eDNA” project led by Bigelow Laboratory and the University of Maine, which uses DNA found in the environment to understand the ecosystems it is sampled from. Countway is particularly interested in using this approach to understand how harmful blooms occur.

All aquatic plants, animals, and microbes leave genetic traces wherever they go as a natural byproduct of their existence. Countway is using this environmental DNA to catalog potentially harmful organisms throughout the year, as well as the bacteria that live alongside them.

“Instead of just focusing on HABs, our approach is to find out what organisms are present and to see if certain members of the microbial community are somehow setting up conditions for a harmful bloom,” he said. “We’re also looking for environmental indicators for blooms. Maybe it has something to do with nutrients, or maybe it’s temperature or salinity. We don’t know yet, so we want to keep an open eye out for patterns we can connect.”

Research to understand how HABs start is critical, but scientists are equally interested in discovering why they end. Senior Research Scientist Joaquin Martínez Martínez studies marine viruses and believes they may be a significant part of the answer.

Last December, he and Postdoctoral Scientist Anne Booker traveled to the Gulf of Mexico to study a record bloom of Karenia brevis, the alga that causes red tide, which had been going on for 15 months. Two weeks before they set sail on the research cruise, the bloom suddenly disappeared.

“We went south, north, east, and west, but we didn’t find a single Karenia cell,” Martínez Martínez said. “How can this bloom be maintained for so long and then terminate out of the blue? We think that interactions with bacteria and viruses are important for bloom dynamics, but they have not yet been studied in detail.”

Research has shown many algae depend on certain bacteria species for survival, and these bacteria may be susceptible to fatal viral infections. Martínez Martínez has also discovered a virus that naturally occurs in the Gulf of Mexico and can infect Karenia brevis. His findings have so far been solely based on samples that were cultured in the laboratory, but Martínez Martínez thinks they could help explain why blooms end in the Gulf of Mexico and beyond.

“If it happens in culture, it might happen in the environment,” he said. “One way or another, viruses seem to contribute to the termination of a bloom. That said, I don’t believe there’s one factor that determines every single outcome. It’s likely a combination of viruses and other processes.”

Safeguarding Seafood

In the Gulf of Mexico, warm waters and nutrient-rich runoff promote blooms of toxic algae every year. In the Gulf of Maine, where climate change is warming and acidifying the waters, conditions are becoming similarly fertile for harmful blooms. This shift is particularly detrimental to New England’s shellfish fisheries, such as oyster, mussels, and clams. HAB toxins build up inside these filter feeders and can harm people when consumed, complicating the management and harvest of seafood resources.

In 2016, a toxic bloom of Pseudo-nitzschia prompted the recall of more than 58,000 pounds of mussels and the closure of hundreds of miles of Maine coastline to shellfish harvesting. In 2017, the first Karenia mikimotoi bloom was idented in Maine waters and caused a clam die-off. Also in 2017, a Pseudo-nitzschia bloom closed Casco Bay to shellfish harvesters in December, when waters have historically been cold enough to inhibit such events.

In Maine, seafood consumers are protected from these toxins by robust toxin monitoring and rapid closures of affected regions. Maine Department of Marine Resources partners with Bigelow Laboratory on the regular testing of samples from all along the coast. The state then uses that data to inform their decisions about when to close and reopen specific harvest areas in response to toxin levels.

“It’s been an incredibly effective system,” said Senior Research Scientist Steve Archer, head of the team that conducts the analysis. “There hasn’t been a fatality since the system was put in place. That’s pretty incredible when you realize how toxic some of this stuff is.”

Since they started collaborating with the state government in 2014, Archer’s team has screened tens of thousands of shellfish samples for a dozen toxic compounds related to diarrhetic shellfish poisoning, amnesic shellfish poisoning, and paralytic shellfish poisoning. The collaboration has created a massive dataset of information on when and where toxins occur.

In 2018, Archer and Senior Research Scientist Nick Record started collaborating with Maine officials and shellfish farmers to develop a toxicity forecast. Applying artificial intelligence, they use the data from Bigelow Laboratory to predict fishery closures due to toxins a week ahead of time. The researchers started publishing the regular forecast two years ago, providing shellfish farmers and resource managers early warning of likely harmful algal blooms.

“This short-term forecasting is a climate adaptation tool,” Record said. “The environment is changing more rapidly and in more unexpected ways than ever before. If we can provide a reliable glimpse of what’s coming in the next week, month, or year, we can help people be proactive in decision-making.”

In addition to developing a computationally powered approach for Maine, Record recently started working on a United Nations-supported effort to build HAB early warning systems in countries without strong monitoring capabilities. This year, he and an international team of other forecasting experts began to partner with groups in Namibia and Morocco to assess local needs and co-develop a path forward.

Growing Communities

From Maine to Africa, HAB mitigation efforts highlight the importance of community involvement. Record said it would be easier to just use scientific data to create predictive models, but they’d likely be wasted e orts without factoring in the perspectives of those living and working in the region.

“A really important part of this research is stepping away from the lab and talking with people who are working in aquaculture or managing natural resources,” Record said. “You have to ask what kind of forecast they could use, what kind of information they want, and what would actually help them.”

In New England, Sipler and Countway also work with local groups, landowners, and governments to determine the needs that power their research. Maine has thousands of miles of waterfront and only a handful of researchers studying HABs. Through efforts like the Maine eDNA project and Bigelow Laboratory’s Water Health and Humans Initiative, the researchers collaborate with communities to monitor local conditions.

“The number one way that we are able to identify harmful algal blooms is because someone sees a change in their environment and reports it,” Sipler said. “Our goal is to give communities the power to monitor their own waters, and then we can be a resource to help interpret and utilize the information they’re gathering.”

Some of these efforts are as simple as environmental journals or photo documentation. Others are more complex. Countway has been working to train communities on how to use genetic testing methods, similar to what he uses in the laboratory to identify organisms.

“Recently, the door has been flung wide open on access to DNA technology,” Countway said. “The really cool thing is that we can take portable technology out to the field to work with community groups at the location that they care about. We can show them the tools they need to do some pretty advanced analysis, all on something as accessible as a smartphone.”

Efforts to monitor for HABs and avoid their harmful impacts are increasing in tandem with the threat. This is providing scientists, communities, and resource managers with new suites of tools. However, as the earliest records show, these organisms have been around far longer than human society. Ultimately, people have to learn how to best live with them.

“Many of these organisms have been around for millions, if not billions, of years, and they’re not just going to disappear,” Countway said. “While avoidance is currently the best tactic, we can learn to better coexist and reduce their harm once we understand what drives their blooms and causes them to end.”

Photo Captions:

Photo 1: A bloom of the harmful algae Karenia brevis is visible off the coast of Sarasota, Florida, in August 2018.

Photo 2: Cyanobacteria from Sabattus Pond float in a water sample on a microscope slide.

Photo 3: Intern Katie Baker, left, and UMaine doctoral student Sydney Greenlee, right, collect water samples from the Bigelow Laboratory dock to study Pseudo-nitzschia