(ORDO NEWS) — In the second largest estuary in the United States, scientists have recorded a mass extinction of marine parasites.
Researchers from the University of Washington found that over the past 140 years, from 1880 to 2019, the number of parasites in Puget Sound, Washington, decreased by 38% for every degree Celsius of sea surface temperature increase. That is, parasites have become more than 50% less.
This study represents the largest and longest set of data on parasite abundance anywhere in the world, and the results are even worse than conservationists feared. Scientific article published in PNAS.
Reducing the number of creatures that use the resources of others is generally considered a good thing. But this is an outdated view. Parasites are invisible threads that help tie food webs together.
Since many of these animals have very complex life cycles, by exploiting hosts of different trophic levels, they essentially cement the ecosystem and strengthen ecological ties between different groups.
Parasites are a factor in evolution. If we look at relationships in host-parasite pairs, we find a significant similarity of strategies with analogous predator-prey pairs.
By forcing them to somehow adapt to their presence, the parasite actually stimulates the evolution of the host, and its influence is very multifaceted. How ecosystems will cope without their influence is unclear.
According to recent findings in Puget Sound, parasites with three or more hosts (slightly more than half of all species studied) were found to be particularly vulnerable to warming waters. Losses of parasites may match or even exceed the rate of mass extinction among other species.
“If the same degree of loss were observed among mammals or birds, this would immediately trigger conservation measures, but it is not customary to pay attention to parasites,” says parasitologist Chelsea Wood from the University of Washington.
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