Ocean warming has destroyed many marine parasites, study suggests

Ocean warming has destroyed many marine parasites, study suggests

Ocean warming has destroyed many marine parasites, study suggests

Ocean warming has destroyed marine parasites, suggesting they may be especially vulnerable to climate change, the researchers say.

More than a century of preserved fish specimens offer a rare glimpse into long-term trends in parasite populations, according to a new study.

Research from the University of Washington (UW) indicates that the number of fish parasites declined from 1880 to 2019, a 140-year period when Puget Sound, their habitat and the second-largest estuary in the continental United States, warmed significantly. .

The researchers say that if a similar level of decline were to occur in species that people are “concerned about,” it would trigger conservation efforts.

While the tiny creatures strike fear or disgust in many, their decline is worrisome news for ecosystems, scientists say.

Lead author Chelsea Wood, a UW associate professor of aquatic and fisheries sciences, said: “People generally think that climate change will make parasites thrive, that we’ll see an increase in parasite outbreaks as the world gets heats up.

“For some parasite species, that may be true, but parasites are host-dependent, and that makes them particularly vulnerable in a changing world where host fates are reshuffled.”

The researchers say the study is the world’s largest and longest dataset on parasite abundance in wildlife.

It suggests that parasites may be especially vulnerable to a changing climate.

Although some parasites have a single host species, many travel between host species.

The eggs are carried in one species, and then when the larvae emerge, they infect another host and the adult may reach maturity on a third host before laying eggs, the researchers say.

Dr Wood said: “Our results show that parasites with one or two host species remained fairly stable, but parasites with three or more hosts crashed.

“The degree of decline was severe. It would trigger conservation action if it happened in the kinds of species that people care about, like mammals or birds.”

He added: “Parasite ecology is really in its infancy, but what we do know is that these complex life-cycle parasites likely play an important role in driving energy through food webs and supporting major predators”.

The researchers used a new method to resurrect information about parasite populations from the past.

Mammals and birds are preserved using taxidermy, which retains parasites only on the skin, feathers, or fur.

However, specimens of fish, reptiles, and amphibians are kept in liquid, which also preserves any possible parasites that were living inside the animal at the time of its death.

The study focused on eight species of fish that are common in the behind-the-scenes collections of natural history museums.

Most of the samples came from the UW Fish Collection at the Burke Museum of Natural History and Culture.

The researchers carefully cut up the preserved fish specimens and then identified and counted the parasites they discovered inside before returning the specimens to museums.

A preserved fish specimen that has been inspected for parasites.

A preserved fish specimen that has been inspected for parasites (Katherine Maslenikov/UW Burke Museum)

The researchers discovered a number of different parasites, including arthropods, or animals with an exoskeleton, including crustaceans, as well as what Dr. Wood describes as “stunningly beautiful tapeworms.”

In all, the team counted 17,259 parasites, of 85 types, from 699 fish specimens.

Dr. Wood explained, “This study demonstrates that significant parasite declines have occurred in Puget Sound.

“If this can go unnoticed in an ecosystem as well studied as this, where else could it be happening?”

He added: “Our result draws attention to the fact that parasitic species could be in real danger.

“And that could mean bad things for us, not just fewer worms, but fewer parasite-driven ecosystem services we’ve come to depend on.”

The findings are published in the Proceedings of the National Academy of Sciences.

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