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வெப்பமயமாதல் பெருங்கடல்கள் கடல் ஒட்டுண்ணிகளை அழித்துள்ளன


ஒட்டுண்ணி புழுக்கள்

இந்த மோனோஜெனிய புழுக்கள் (மைக்ரோகோடைல் செபாஸ்டிஸ்) பர்க் அருங்காட்சியகத்தில் உள்ள UW மீன் சேகரிப்பில் இருந்து பாதுகாக்கப்பட்ட செப்பு ராக்ஃபிஷ் மாதிரியின் செவுள்களில் இருந்து பிரிக்கப்பட்டது. கடன்: கேட்டி லெஸ்லி/வாஷிங்டன் பல்கலைக்கழகம்

100 ஆண்டுகளுக்கும் மேலாக பாதுகாக்கப்பட்ட மீன் மாதிரிகள் காலப்போக்கில் ஒட்டுண்ணி மக்கள்தொகை போக்குகளில் ஒரு தனித்துவமான தோற்றத்தை அளிக்கின்றன. இருந்து ஒரு ஆய்வு வாஷிங்டன் பல்கலைக்கழகம் 1880 முதல் 2019 வரை மீன் ஒட்டுண்ணிகள் குறைவதை வெளிப்படுத்துகிறது, இந்த காலகட்டத்தில் அவற்றின் வாழ்விடமான புகெட் சவுண்ட் (அமெரிக்காவின் இரண்டாவது பெரிய முகத்துவாரம்) குறிப்பிடத்தக்க வெப்பமயமாதலை அனுபவித்தது.

ஒரு ஆய்வு சமீபத்தில் வெளியிடப்பட்டது தேசிய அறிவியல் அகாடமியின் செயல்முறைகள்வனவிலங்கு ஒட்டுண்ணி எண்களின் உலகின் மிகப்பெரிய மற்றும் நீண்ட பதிவு, ஒட்டுண்ணிகள் காலநிலை மாற்றத்திற்கு மிகவும் எளிதில் பாதிக்கப்படலாம் என்பதைக் குறிக்கிறது.

பாதுகாக்கப்பட்ட மீன் ஜாடி

பர்க் அருங்காட்சியகத்தில் உள்ள UW மீன் சேகரிப்பில் இருந்து திரவ-பாதுகாக்கப்பட்ட மீன் மாதிரிகளின் ஜாடி. இந்த மீன்கள் 1991 இல் ஹூட் கால்வாயில் சேகரிக்கப்பட்டன. கடன்: கேத்தரின் மஸ்லெனிகோவ்/யுடபிள்யூ பர்க் மியூசியம்

“காலநிலை மாற்றம் ஒட்டுண்ணிகள் செழித்து வளரும் என்று மக்கள் பொதுவாக நினைக்கிறார்கள், உலகம் வெப்பமடைகையில் ஒட்டுண்ணி வெடிப்புகள் அதிகரிப்பதைக் காண்போம்” என்று UW நீர்வாழ் மற்றும் மீன்வள அறிவியலின் இணை பேராசிரியரான செல்சியா வுட் கூறினார். “சில ஒட்டுண்ணிகளுக்கு[{” attribute=””>species that may be true, but parasites depend on hosts, and that makes them particularly vulnerable in a changing world where the fate of hosts is being reshuffled.”

While some parasites have a single host species, many parasites travel between host species. Eggs are carried in one host species, the larvae emerge and infect another host and the adult may reach maturity in a third host before laying eggs.

Rockfish Specimen

This copper rockfish (Sebastes caurinus) was collected in 1964 in Puget Sound. The study included eight fish species and found a dramatic decline in the number of parasites over time. Credit: Natalie Mastick/University of Washington

For parasites that rely on three or more host species during their lifecycle — including more than half the parasite species identified in the study’s Puget Sound fish — analysis of historic fish specimens showed an 11% average decline per decade in abundance. Of 10 parasite species that had disappeared completely by 1980, nine relied on three or more hosts.

“Our results show that parasites with one or two host species stayed pretty steady, but parasites with three or more hosts crashed,” Wood said. “The degree of decline was severe. It would trigger conservation action if it occurred in the types of species that people care about, like mammals or birds.”

Jars of Herring

The UW Fish Collection is a state-supported facility that houses more than 300,000 adult fish specimens. The jar on the left contains herring (Clupea pallasii) collected in 1952. Credit: Katherine Maslenikov/UW Burke Museum

And while parasites inspire fear or disgust — especially for people who associate them with illness in themselves, their kids or their pets — the result is worrying news for ecosystems, Wood said.

“Parasite ecology is really in its infancy, but what we do know is that these complex-lifecycle parasites probably play an important role in pushing energy through food webs and in supporting top apex predators,” Wood said. She is one of the authors of a 2020 report laying out a conservation plan for parasites.

Wood’s study is among the first to use a new method for resurrecting information on parasite populations of the past. Mammals and birds are preserved with taxidermy, which retains parasites only on skin, feathers, or fur. But fish, reptile, and amphibian specimens are preserved in fluid, which also preserves any parasites living inside the animal at the time of its death.

Preserved Fish Specimen

A researcher holds open a preserved fish specimen that has been inspected for parasites. The study included eight fish species and 699 fish specimens, which yielded more than 17,000 parasites. Credit: Katherine Maslenikov/UW Burke Museum

The study focused on eight species of fish that are common in the behind-the-scenes collections of natural history museums. Most came from the UW Fish Collection at the Burke Museum of Natural History and Culture. The authors carefully sliced into the preserved fish specimens and then identified and counted the parasites they discovered inside before returning the specimens to the museums.

“It took a long time. It’s certainly not for the faint of heart,” Wood said. “I’d love to stick these fish in a blender and use a genomic technique to detect their parasites’ DNA, but the fish were first preserved with a fluid that shreds DNA. So what we did was just regular old shoe-leather parasitology.”

Among the multi-celled parasites they found were arthropods, or animals with an exoskeleton, including crustaceans, as well as what Wood describes as “unbelievably gorgeous tapeworms:” the Trypanorhyncha, whose heads are armed with hook-covered tentacles. In total, the team counted 17,259 parasites, of 85 types, from 699 fish specimens.

UW Fish Collection

Pacific herring (Clupea pallasii) specimens on a shelf in the UW Fish Collection at the Burke Museum. This behind-the-scenes collection provided most of the specimens used in the 140-year study of parasite abundance. Credit: Katherine Maslenikov/UW Burke Museum

To explain the parasite declines, the authors considered three possible causes: how abundant the host species was in Puget Sound; pollution levels; and temperature at the ocean’s surface. The variable that best explained the decline in parasites was sea surface temperature, which rose by 1 degree Celsius (1.8 degrees Fahrenheit) in Puget Sound from 1950 to 2019.

A parasite that requires multiple hosts is like a delicate Rube Goldberg machine, Wood said. The complex series of steps they face to complete their lifecycle makes them vulnerable to disruption at any point along the way.

“This study demonstrates that major parasite declines have happened in Puget Sound. If this can happen unnoticed in an ecosystem as well studied as this one, where else might it be happening?” Wood said. “I hope our work inspires other ecologists to think about their own focal ecosystems, identify the right museum specimens, and see whether these trends are unique to Puget Sound, or something that is occurring in other places as well.

“Our result draws attention to the fact that parasitic species might be in real danger,” Wood added. “And that could mean bad stuff for us — not just fewer worms, but less of the parasite-driven ecosystem services that we’ve come to depend on.”

Reference: “A reconstruction of parasite burden reveals one century of climate-associated parasite decline” by Chelsea L. Wood, Rachel L. Welicky, Whitney C. Preisser, Katie L. Leslie, Natalie Mastick, Correigh Greene, Katherine P. Maslenikov, Luke Tornabene, John M. Kinsella and Timothy E. Essington, 9 January 2023, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2211903120

The study was funded by the National Science Foundation, the UW-based Cooperative Institute for Climate, Ocean, and Ecosystem Studies, the Alfred P. Sloan Foundation, the University of Washington and the Washington Research Foundation.



Mr.Mario
Mr.Mario
I am a tech enthusiast, cinema lover, and news follower. and i loved to be stay updated with the latest tech trends and developments. With a passion for cyber security, I continuously seeks new knowledge and enjoys learning new things.

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