As if there wasn’t enough to worry about with climate change, a University of Missouri-Columbia researcher suggests we add more thing to our list: worms.
Rising sea levels around coastal river deltas could lead to rising prevalence of trematode infestations, flatworm parasites commonly known as flukes that can cause infections and internal organ inflammation if eaten by humans.
Their numbers increased significantly starting about 9,600 years ago, according to research led by John Huntley, a paleobiologist at MU’s department of geologic sciences. That’s when a rise in sea levels began around the Pearl River delta in Southeast China. His analysis of the mollusk fossil record there shows that the prevalence of flatworms that used the shellfish as their hosts rose significantly.
“What we can say is there’s a strong relationship between the first 300 years of rise in sea level and prevalence,” Huntley said in an interview.
The fossil record could hold lessons as humans work to adapt to rising sea levels caused by climate change, Huntley said. If another significant flatworm uptick happens, it could affect fisheries and disrupt food systems or lead to higher infection rates among humans.
In Huntley’s research, published in the journal The Proceedings of the National Academy of Science, the mollusk infestation rate rose to somewhere between 20 and 40 percent during the sea level rise, before falling off as sea levels peaked. Before the waters began rising, infestation rates ranged between 10 to 20 percent, Huntley said. Neither rise was correlated with the water’s salinity or with an uptick in the clam population.
The phenomenon of rising flatworm prevalence during rising sea levels was also documented in the Adriatic Sea by a team that included Huntley.
“We already knew the history, and when you parse out the prevalence values into that history, the pattern is quite strong,” Huntley said. “The tricky part comes in trying to parse out which environmental variables might be causing this pattern. Because as sea levels rise, you’re changing a lot of variables.”
He cautioned the environment has changed a lot since humans arrived on the planet.
“It could be something to be concerned about in the current centuries,” he said. “But we should also consider too that humans are also altering the environment in ways that are not really comparable.”
There’s plenty else to be worried about as the temperature rises, Huntley admitted, but he said the flatworms his team studied can have a significant impact on coastal ecosystems.
“Is it going to be the big killer from climate change? Probably not,” he said. “But these are potentially pretty effective parasites.”