Trials of Toxic Algae Link Gulfs of Mexico and Maine

It isn’t every day that algae make national headlines. During the last month, however, they’ve commanded the nation’s attention as red tide afflicts Florida’s coast – and in turn, its residents, marine animals, and economy.

Red tide is caused by the proliferation of a harmful microalgae. Like plants on land, algae in the ocean support ecosystems by processing nutrients and feeding animals — but some also produce toxins. When large numbers of these species grow, or bloom, toxins can move up the food chain and accumulate to harmful levels in fish, shellfish, and mammals.

There is evidence of harmful algal blooms in the Gulf of Mexico as far back as the 17th century. In 1648, Spanish sailors encountered a “mountain of dead fish near the coast” – a fish kill that was likely caused by Karenia brevis, the same species of algae causing the unusually large and prolonged red tide that is currently distressing Florida.

“The Gulf of Mexico is naturally prone to harmful algal blooms,” said Deborah Bronk, president and CEO of Bigelow Laboratory for Ocean Sciences, who has extensively studied this phenomenon in Florida. “Human activities have made these blooms worse over time, and this year is the big one.”

Water conditions and currents cause significant harmful algal blooms to develop in the Gulf of Mexico almost every year. Nitrogen is an essential nutrient usually in scarce supply in the ocean, but nitrogen-rich runoff from the land acts as fertilizer, which can cause toxic algae to rapidly multiply into a bloom. Physics also plays a key role: when currents and wind combine to aggregate these algae, toxins can reach a level where they start killing fish and other animals. This year, the harmful algal bloom has sickened and killed fish, turtles, dolphins, manatees, whales, and even a whale shark.

“We’ve seen blooms this severe before, and need consistent, sound research to help us predict and mitigate red tides without impacting the rest of the environment,” said researcher Cynthia Heil, who ran Florida’s red tide monitoring program between 2003 and 2010, before joining Bigelow Laboratory. “One of the big questions about blooms in Florida is, what are the effects of climate change?”

As global climate changes, the Gulf of Maine is warming and becoming more acidic — conditions that may also favor toxic species and cause the Gulf to become more susceptible to harmful algal blooms. In recent years, new species of toxic algae have turned up in Maine and unusually timed blooms have closed shellfisheries.

“In a changing climate, we may have to face harmful algal blooms that are more widespread and persist for longer periods of time,” Senior Research Scientist Pete Countway said. “My goal is to detect and quantify the population dynamics of these potentially harmful organisms to provide resource managers with as much advance warning as possible.”

Countway uses a variety of DNA-based molecular techniques to detect harmful algae at very low abundances, before they cause a bloom. He aims to lead an effort in Maine to introduce handheld genetic testing equipment to citizen scientists and other stakeholders.

“These handheld devices have amazing potential to get the public involved with sampling for harmful algal blooms along the coast of Maine,” Senior Research Scientist Nick Record said. “Citizen scientists have already been key in detecting blooms in Maine, and this could greatly expand our ability to predict the timing and magnitude of these blooms.”

Maine has already experienced an influx of toxic species that have disrupted its valuable shellfish industry. In 2017, the first Karenia mikimotoi bloom was identified in the state’s waters, causing a clam die-off and concern to harvesters. Pseudo-nitzschia can produce domoic acid, a neurotoxin that causes amnesic shellfish poisoning. In 2016, a toxic bloom of Pseudo-nitzschia prompted the recall of more than 58,000 pounds of blue mussels and closed hundreds of miles of Maine coastline to shellfish harvesting. In 2017, a rare late-season Pseudo-nitzschia bloom closed Casco Bay to clam diggers and other harvesters. It also puzzled managers, who are accustomed to cold December water temperatures limiting such blooms.

“The Gulf of Maine is incredibly dynamic,” Senior Research Scientist Steve Archer said. “There aren’t many barriers in the ocean. We must expect algae species to move, and track that.”

Archer directs Bigelow Analytical Services, which processes shellfish samples from around the country to detect toxins and help inform management responses. He has observed shifting populations of algae in Maine, and believes that, as waters warm, the ecosystem could favor species new to the region.

“Just as in Florida, there are very good monitoring systems in the Gulf of Maine, which can help us detect and ultimately predict blooms,” Archer said. “We need to use resources efficiently to keep vigilant against potential harmful changes.”

Predicting blooms will be a powerful and essential tool to help the state adjust to a changing Gulf of Maine. During the 2016 bloom, Countway used genetic tools to identify a Pseudo-nitzschia species as the culprit, and he believes these same tools can help managers create specific, proactive assessments before blooms develop and harm the shellfish industry.

“Many different triggers can cause these blooms,” Countway said. “We’d like to be able to see the blooms coming and provide specific information to prevent the economic losses that come with shellfish recalls.”

Bronk believes that it is also important to limit blooms as much as possible by minimizing the amount of nitrogen humans add to the Gulf of Maine. Managing land development, erosion, and wastewater treatment can all help keep the system clean and prevent blooms from arising. Improving local water quality by remediation techniques like kelp farming can also help the ecosystem stay healthy.

“You can’t control the physics of the ocean, but you can control how many excess nutrients pollute the Gulf of Maine,” Bronk said. “We have learned that if the ecosystem is healthy, it can withstand these kinds of disturbances.”