Oceans: Scientists sound warning on harmful algae blooms

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A NASA satellite captured a large bloom of phytoplankton off the coast of New York and New Jersey in Aug. 2015. Photo courtesy NASA Earth Observatory.

More research needed to track trends

Staff Report

Scientists tracking the northward track and seasonal shift of potentially harmful plankton are warning that the trends do not bode well for ecosystems and human health.

Presenting recent findings at an international conference, biologists said  the future may bring more harmful algal blooms and called for changes in research priorities to better forecast these long-term trends.

The intense toxic phytoplankton blooms off the west coast of North America this summer appear to be associated with unusual warming-related conditions. Scientists also suspect such blooms may be a factor in a die-off off endangered right whale calves off the coast of Argentina.

“Does this large scale harmful algal bloom provide a window into the future?” said Dr. Vera Trainer of NOAA Fisheries’ Northwest Fisheries Science Center. “While it still is unclear, there is reason for substantial concern.”

The published conference findings are that, while there are reasons to expect HABs to increase with climate change, poor scientific understanding seriously limits forecasts, and current research strategies will not likely improve this capacity.

The impacts of algal blooms are extensive. Although phytoplankton blooms normally fuel productive ecosystems, some blooms create very low oxygen concentrations in bottom waters, killing or driving out marine fish or benthic organisms. Others produce potent neurotoxins that threaten ecosystems and human health.

Evidence suggests that these destructive blooms, called red tides in the past but more properly “harmful” algal blooms, are increasing in frequency and severity, possibly from human causes.

“There is growing concern among scientists that climate change may exacerbate this trend,” said Prof. Mark Wells, University of Maine and organizer of the workshop. “We are frustrated by the inadequate national research focus to determine the likelihood of these worst-case scenarios.”

The combined effects of increasing temperature and atmospheric CO2 are affecting ocean surface temperatures, nutrients, light, and ocean water acidity, all of which affect marine ecosystems. These factors influence not just the intensity of algal blooms but also their composition. The question is whether climate change will enable harmful species to outcompete other phytoplankton.

“It is critically important that we learn as much as possible, as precisely as possible, to fill the critical gap in knowledge between the current and the future phytoplankton community structure,” says Professor Charles Trick, Western University, Canada.

The workshop participants developed several urgent recommendations on research priorities. These include re-orientating research to study how harmful species interact in planktonic communities, focus more intensive study on key organisms, emphasize developing ecological and forecast models, and strengthen linkages among global, national and regional observation programs.

“Past research has brought great understanding of individual HAB organisms; future work must concentrate on how these harmful species fit into their ecosystems. It is the most significant coastal challenge facing society today,” said Trick.

Although workshop participants were optimistic, they urged fundamental shifts in HAB research so that science can better inform public debate over climate change effects on the oceans, rather than just seeking to explain destructive patterns after they develop.

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