Something Terrible Has Been Discovered in the World’s Largest Parasite Study. They’re Dead.

Not all parasites are harmful, and in a world that is undergoing rapid change, they require our protection, but it does not appear that they are receiving it.

In point of fact, scientists have documented a massive extinction of marine organisms that depend on free-living hosts for survival in the second-largest estuary in the United States.

The number of parasites in Puget Sound decreased by 38% for every degree Celsius increase in sea surface temperature over the past 140 years, from 1880 to 2019, according to UW researchers.

The findings are even worse than some conservationists had anticipated, and it is the world’s longest and largest dataset on parasite abundance.

Food webs are held together by parasites, which are invisible threads. It is unclear how ecosystems will fare without their influence.

According to UW parasitologist Chelsea Wood, “The findings are a real bummer if you care about biodiversity or you know anything about parasites.”

“The declines that we observed shocked even me.”

Wood claims that conservation efforts would immediately begin if the same level of loss were observed in birds and mammals.

For instance, the decline of birds in North America between 1970 and 2017 was just over 6% per decade, and they already play a significant role in conservation plans.

Parasites, on the other hand, are of no real concern to anyone. A decrease in the number of creatures that steal other people’s life is typically regarded as positive. However, that is a dated viewpoint that overlooks the larger picture.

Today, many scientists agree that climate change is driving Earth toward a mass extinction, but the situation looks even worse when we consider how much life forms on Earth rely on parasites—the vast majority of which are unknown—unaccounted for.

Despite their widespread and crucial role in maintaining ecological balance, parasites are not taken into consideration in very many ecological surveys at the moment, and conservation efforts almost always overlook their connective role in a habitat.

We usually don’t notice parasites until they multiply and become a problem.

For instance, Wood’s lab at the University of Washington made headlines in 2020 when it discovered that a particular parasitic worm found in raw seafood had increased by 280 times since the 1970s.

However, not every parasite is doing well. In fact, the current climate crisis probably has a negative impact on many of them. They are disappearing faster than we can count them, like bubbles in a boiling pot.

Parasites with three or more hosts, or just over half of all parasites sampled, appeared to be particularly susceptible to warming waters in the most recent Puget Sound findings.

As for the reason, it’s possible that rising temperatures put parasites in direct physiological danger or that warming waters are affecting the availability and viability of their hosts.

In either case, a parasite’s vulnerability to climate changes likely increases with the number of hosts it must bounce between.

Nine of the 10 parasites that Wood found in Puget Sound that had vanished by 1980 had life cycles that required three or more hosts.

Wood asserts, “What we expect when we look at a changing environment is winners and losers.”

“But what we found here were a whole bunch more losers than we were anticipating.”

Wood believes that parasite losses could match or even exceed the mass rate of extinction occurring among free-living species if Puget Sound is anything like other ecosystems worldwide.

However, unless additional researchers follow in Wood’s footsteps, no one can say for sure if that is the case.

Wood believes that the way parasites are currently viewed is comparable to how apex predators like wolves and bears were viewed in the 1960s and 1970s. Fear and resentment drove humans to hunt large carnivores to the point of extinction for centuries.

Scientists didn’t realise what had been done until the middle of the twentieth century. To the detriment of habitats all over the world, the world had removed some of the most fundamentally important movers and shakers in ecosystems in a systematic manner.

It turns out that apes weren’t always bad for things; They were vital stabilisers of habitat. Ecosystems flourished once more when they were brought back into their natural habitats.

“That’s where we are for parasites,” according to Wood, “We’re at this moment when research is starting to accumulate to suggest how awesomely powerful parasites are in an ecosystem. But that information hasn’t yet leaked out to the public.”

A 2017 study on 457 parasite species predicted that up to 10%, including 30% of parasitic worms, could be extinct by 2070. The first endangered parasite “red list” was created by the authors in response to the findings.

In 2020, Wood and other researchers from around the world came up with a 12-goal plan for the future of parasite conservation.

The paper’s co-author, Colin Carlson, told The Atlantic in 2015 that the first step is to stop killing parasites when we find them.

Carlson stated to reporter Ed Yong, “The most fundamental idea, and it’s a bit silly that we’ve missed this, is you don’t destroy something if it’s doing okay.”

Data collection and synthesis is the next step, and Wood is leading the way in this subfield. Her lab at the University of Washington is the first to use fish samples from museums to create a historical timeline of the number of marine parasites.

According to Wood, “No one has noticed anything like this. And part of it is that no one’s looking.”

Parasites, in contrast to apex predators, are more difficult to spot if you aren’t actively looking for them. Furthermore, the work of finding them is not exactly glamorous.

According to Wood, “Your fieldwork is sitting in the basement of a museum, dissecting fish that are suffused with disgusting chemicals.”

“It doesn’t have sex appeal. But it gives us the opportunity to time travel. And if I get the chance to time travel, I’ll sniff some formalin fumes.”

We can count the parasites of the present and the past. Now all that is required of us is to dive.

The research was presented in PNAS.


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