Red Tides forecast for return to New England

Red tides or Harmful algal blooms (HAB), refer to a proliferation of toxic algae (most commonly phytoplankton such as dinoflagellates) that cause a negative impact to the surrounding marine environment – and are an annual occurrence off of New England’s coast line. These algal blooms often differ in intensity each year, with some of the more extreme past events being responsible for detrimental ecological and economic effects in the region.

This week it has been revealed that New England’s spring and summer red tides will be similar in extent to those of the past three years, according to the 2015 Gulf of Maine red tide seasonal forecast. Funded by the National Oceanic and Atmospheric Administration (NOAA), the forecast is the eighth seasonal Gulf of Maine red tide forecast and issued by scientists from the Woods Hole Oceanographic Institution and North Carolina State University.

Currently 85 toxic microalgal species have been documented, with notable blooms consisting of dinoflagellates of the genus Alexandrium and Karenia, or diatoms of the genus Pseudo-nitzschia. Effects of HABs include massive fish kills, devastation of critical coastal habitats, vital shellfish resource loss, illness and death of protected marine species, and threats to human health.  New England surfers from varying degrees of HABs annually, with the most notable culprit being Alexandrium, an alga also known as New England Red Tide. Alexandrium produces a potent toxin that accumulates in shellfish which can result in serious or even fatal illness in humans who eat contaminated shellfish. Such blooms have resulted in shellfish harvesting closures in the region due to impact on stocks. In 2005, an unusually large red tide event caused $23 million in lost shellfish sales in Massachusetts and Maine.

While most of species of phytoplankton and cyanobacteria are harmless, there are a few dozen that naturally produce potent toxins given the right conditions and it these species that are often associated with large-scale marine mortality events and also with various types of shellfish poisonings in humans. Some HABs also instigate negative environmental impacts through creating a hypoxic environment. Through extreme proliferation of these algal cells, blooms can reduce the dissolved oxygen content of seawater creating ‘dead zones’ where most marine life cannot survive in.

The red tide forecast that alerts of incoming blooms is part of a larger NOAA effort to deliver ecological forecasts that support human health and well-being, coastal economies, and coastal and marine stewardship. The seasonal forecast is generated by modelling how algal cysts will respond to predicted ocean conditions and is used to guide state monitoring. State monitoring in affected areas involves conducting rigorous testing of toxin levels in shellfish and, when necessary, ban harvesting to protect human health.

Woods Hole will also maintain three robotic HAB sensors called environmental sample processors (ESPs) at locations along the Maine coast throughout the spring and summer. This is the first year the Maine Department of Marine Resources (DMR) will provide their direct measurements of shellfish toxicity to researchers for comparison with estimates derived from near-real time ESP data on Alexandrium cells to try to predict toxicity in shellfish.

“We are working with the researchers at Woods Hole to further explore the relationship between the direct shellfish toxicity measurements onshore and the predictions of toxicity from the ESPs located offshore,” said Kohl Kanwit, director of the Bureau of Public Health for the Maine DMR. “The ESPs are not a replacement for state-run programs that monitor naturally occurring marine toxins in shellfish, but they can possibly increase our program efficiency in the future by providing automated data collection that can inform on-the-ground decision making.”

“This partnership on the Gulf of Maine seasonal HAB forecast and use of ESPs to detect toxic red tide offshore are examples of NOAA’s role in improving ecological forecasting capabilities along our coasts,” said Holly Bamford, Ph.D., assistant NOAA administrator for NOAA’s National Ocean Service performing the duties of the assistant secretary of commerce for conservation and management. “Advance warning of toxic HAB events enables proactive actions to protect coastal economies, making the region more resilient to red tide outbreaks.”

In addition to the seasonal forecast, NOAA funds Woods Hole and North Carolina State University to issue weekly updates throughout the bloom season. Updates report bloom extent, trajectory, and intensity. Scientists also report cell abundance and toxin concentrations transmitted in real-time from ESPs strategically placed offshore of shellfish beds. NOAA and Woods Hole developed the toxin detection sensors. Updates are distributed to more than 150 coastal resource and fisheries managers in six states as well as federal agencies such as NOAA, the Food and Drug Administration and the Environmental Protection Agency. Summaries are available at

– JK

Photo Header Credit:  Dead fish in the aftermath of a harmful algal bloom

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