Global climate change underlies a 35-year warming trend that has powerfully affected oceans with toxic algae and has inadvertently impacted human health via the food chain, Long Island scientists have found.
Christopher Gobler, a professor in the School of Marine and Atmospheric Sciences at Stony Brook University, who has circled the globe studying ocean health, has discovered how a broad range of sealife can be damaged by algal toxins, including species consumed as food by human cultures worldwide.
“There are certain algae that make toxins and we don’t fully know in all cases why they do that. One hypothesis is that it is a way to protect themselves from predators,” Gobler said Friday.
Toxic algae caused a massive fish kill a year ago in South America where more than 20 million salmon were waylaid by an algal poison.
In people, these poisons can interfere with sodium ion channels, gateways for the conduction of nerve impulses. Toxin-containing seafood can lead to muscle weakness, even paralysis and death, Gobler said
“Typically the symptoms come on shortly after eating seafood,” Gobler said, underscoring there have been no documented cases of the poisonings on Long Island, although people have been poisoned elsewhere in the world.
Algae include a variety of aquatic organisms capable of photosynthesis — the process by which sunlight is used to synthesize energy from carbon dioxide and water. It’s the same process that all plant life — trees, flowers and crops — use to convert sunrays into fuel. Fresh and salt water are homes to algae.
Pond scum is a familiar form as are seaweeds, such as kelp. Algal blooms refer to the rapid increase — the spread of algae in any aquatic system.
In a new analysis, Gobler and a team of scientists found the oceans have been markedly rising in temperature since 1982, the result of worldwide climate change, a trend that has made the seas more hospitable to toxic algae, Gobler said.
Through painstaking research involving collaborators in a variety of fields, Gobler said they found potent evidence that warmer oceans have facilitated explosive toxic algae growth worldwide.
“There has been rapid growth and a longer bloom season,” Gobler said. “The blooms are now able to start earlier in the year and last longer.”
The scientists were able to prove that oceans have become significantly warmer over the past 35 years by studying sea-surface temperature records. This in turn allowed them to model trends in algae growth rates and bloom-season duration for two of the most toxic, harmful and widespread algal species.
Their research, which was published this past week in the Proceedings of the National Academy of Sciences, identified the two particularly nasty algal species as Alexandrium and Dinophysis. Both are indigenous to the North Atlantic and North Pacific oceans, but are found elsewhere.
[Gobler’s colleague Owen Doherty of the Scripps Institution of Oceanography in San Diego said the research was able to show how global climate change affects ocean health because the team was composed of a diverse group of scientists, each of whom found a different piece of the puzzle.
Doherty said the study demonstrated “the value of interdisciplinary collaboration through a novel combination of laboratory, observational and modeling work.”]
For the seafood-consuming public, the findings are a wake-up call on how warming oceans can pose a threat to human health and national economies.
In March 2016, a deadly algal bloom struck Chile’s fish industry. An estimated 23 million toxin-affected salmon died. Gobler said the loss totaled about $800 million. The culprit in the massive fish kill, he said, was the toxin spewed by Alexandrium algae.
There were so many dead fish, a Chilean official told Reuters last year, they could fill 14 Olympic-sized swimming pools.
“I find that when a lot of people talk about climate change it’s in reference to the future, the end of the century. But it’s not about the future but what has transpired in the last 35 years,” Gobler said.