Sushi Parasite Has Increased 283x in Nearly 40 Years
The population of a marine parasite that sometimes worms its way into sushi has increased by 283 times in the last nearly 40 years, a University of Washington (UW)-led study has found.
The study, published in Global Change Biology Thursday, reviewed the literature and found a significant rise in the abundance of the parasite Anisakis, or "herring worm." This isn't especially concerning for humans, who experience the worm as a nasty bout of food poisoning that then resolves, but it could have serious consequences for marine mammals, who play host to the parasites for years.
"One of the important implications of this study is that now we know there is this massive, rising health risk to marine mammals," study coauthor and UW School of Aquatic and Fishery Sciences assistant professor Chelsea Wood said in the UW press release. "It's not often considered that parasites might be the reason that some marine mammal populations are failing to bounce back. I hope this study encourages people to look at intestinal parasites as a potential cap on the population growth of endangered and threatened marine mammals."
The next time you eat sashimi, nigiri or other forms of raw fish, consider doing a quick check for worms. 🍣😳 https://t.co/juL5dW2NDu— UW SAFS (@UW SAFS)1584649387.0
The researchers looked at a total of 123 papers published between 1967 and 2017 to assess how the abundance of two marine parasites had changed over time: Anisakis and another parasite known as Pseudoterranova, or "cod worm." Anisakis abundance rose 283-fold from 1978 to 2015, while Pseudoterranova abundance did not change. This means that Anisakis has risen from less than one for every 100 hosts caught to more than one in every host caught, ScienceAlert explained.
Ironically, while Anisakis might threaten the health of marine mammals, its rise may have been triggered by their success.
"My gut is that this is about the improvements we've made in marine mammal conservation," Wood told ScienceAlert. "The time frame of our study directly overlaps with when a bunch of really important marine mammal legislation went into effect like the Marine Mammal Protection Act in 1972 and the international whaling commission moratorium on commercial whaling which came in the 1980s."
The one wrinkle in this theory is which mammals usually play host to the worm. Anisakis hatches in the ocean and first infects small animals like shrimp, the UW explained. They then make their way up the food web as the shrimp are eaten by fish, who are eaten by bigger fish, until they end up in the intestines of Cetaceans like whales or dolphins. Here they can live and reproduce for years, reentering the ocean in the animals' feces to start the cycle again.
While Anisakis abundance has risen, Pseudoterranova, which typically infects fish, sea lions and seals, has not. However, seals and sea lions have done much better than whales, Wood told ScienceAlert, which means one would expect Pseudoterranova abundance to have increased instead. However, she speculated it was possible the parasite was actually increasing because it had fewer hosts to pass through.
Other factors that could have caused the rise include the climate crisis and increased runoff from fertilizers, according to the press release.
So what happens if humans happen to ingest one of the worms? Nausea and vomiting that is unpleasant, but temporary.
"When they enter the intestine of a human, it's a great disappointment to the worm. They're not going to be able to complete their life cycle there," Wood told New Scientist.
Wood said that sushi lovers shouldn't worry, as chefs were expert de-wormers.
"I still eat sushi all the time," she told New Scientist.
However, if you are concerned, just cut your nigiri in half and look for worms yourself, she advised in the press release.
A tornado tore through a city north of Birmingham, Alabama, Monday night, killing one person and injuring at least 30.
- Tornadoes and Climate Change: What Does the Science Say ... ›
- Tornadoes Hit Unusually Wide Swaths of U.S., Alarming Climate ... ›
- 23 Dead as Tornado Pummels Lee County, AL in Further Sign ... ›
EcoWatch Daily Newsletter
By David Konisky
On his first day in office President Joe Biden started signing executive orders to reverse Trump administration policies. One sweeping directive calls for stronger action to protect public health and the environment and hold polluters accountable, including those who "disproportionately harm communities of color and low-income communities."
Michael S. Regan, President Biden's nominee to lead the U.S. Environmental Protection Agency, grew up near a coal-burning power plant in North Carolina and has pledged to "enact an environmental justice framework that empowers people in all communities." NCDEQ
- Report Urges Biden to Reverse Trump's Environmental Rollbacks ›
- US Environmental Protection Agency (EPA) ›
- Biden's EPA Pick Michael Regan Urged to Address Environmental ... ›
- Biden Faces Pressure to Tackle 'Unfunded' Toxic Waste Sites ... ›
By Katherine Kornei
Clear-cutting a forest is relatively easy—just pick a tree and start chopping. But there are benefits to more sophisticated forest management. One technique—which involves repeatedly harvesting smaller trees every 30 or so years but leaving an upper story of larger trees for longer periods (60, 90, or 120 years)—ensures a steady supply of both firewood and construction timber.
A Pattern in the Rings<p>The <a href="https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/coppice-standards-0" target="_blank">coppice-with-standards</a> management practice produces a two-story forest, said <a href="https://www.researchgate.net/profile/Bernhard_Muigg" target="_blank">Bernhard Muigg</a>, a dendrochronologist at the University of Freiburg in Germany. "You have an upper story of single trees that are allowed to grow for several understory generations."</p><p>That arrangement imprints a characteristic tree ring pattern in a forest's upper story trees (the "standards"): thick rings indicative of heavy growth, which show up at regular intervals as the surrounding smaller trees are cut down. "The trees are growing faster," said Muigg. "You can really see it with your naked eye."</p><p>Muigg and his collaborators characterized that <a href="https://ltrr.arizona.edu/about/treerings" target="_blank">dendrochronological pattern</a> in 161 oak trees growing in central Germany, one of the few remaining sites in Europe with actively managed coppice-with-standards forests. They found up to nine cycles of heavy growth in the trees, the oldest of which was planted in 1761. The researchers then turned to a historical data set — more than 2,000 oak <a href="https://eos.org/articles/podcast-discovering-europes-history-through-its-timbers" target="_blank" rel="noopener noreferrer">timbers from buildings and archaeological sites</a> in Germany and France dating from between 300 and 2015 — to look for a similar pattern.</p>
A Gap of 500 Years<p>The team found wood with the characteristic coppice-with-standards tree ring pattern dating to as early as the 6th century. That was a surprise, Muigg and his colleagues concluded, because the first mention of this forest management practice in historical documents occurred only roughly 500 years later, in the 13th century.</p><p>It's probable that forest management practices were not well documented prior to the High Middle Ages (1000–1250), the researchers suggested. "Forests are mainly mentioned in the context of royal hunting interests or donations," said Muigg. Dendrochronological studies are particularly important because they can reveal information not captured by a sparse historical record, he added.</p><p>These results were <a href="https://www.nature.com/articles/s41598-020-78933-8" target="_blank">published in December in <em>Scientific Reports</em></a>.</p><p>"It's nice to see the longevity and the history of coppice-with-standards," said <a href="https://www.teagasc.ie/contact/staff-directory/s/ian-short/" target="_blank">Ian Short</a>, a forestry researcher at Teagasc, the Agriculture and Food Development Authority in Ireland, not involved in the research. This technique is valuable because it promotes conservation and habitat biodiversity, Short said. "In the next 10 or 20 years, I think we'll see more coppice-with-standards coming back into production."</p><p>In the future, Muigg and his collaborators hope to analyze a larger sample of historic timbers to trace how the coppice-with-standards practice spread throughout Europe. It will be interesting to understand where this technique originated and how it propagated, said Muigg, and there are plenty of old pieces of wood waiting to be analyzed. "There [are] tons of dendrochronological data."</p><p><em><a href="mailto:firstname.lastname@example.org" target="_blank" rel="noopener noreferrer">Katherine Kornei</a> is a freelance science journalist covering Earth and space science. Her bylines frequently appear in Eos, Science, and The New York Times. Katherine holds a Ph.D. in astronomy from the University of California, Los Angeles.</em></p><p><em>This story originally appeared in <a href="https://eos.org/articles/tree-rings-reveal-how-ancient-forests-were-managed" target="_blank">Eos</a></em> <em>and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.</em></p>
Earth's ice is melting 57 percent faster than in the 1990s and the world has lost more than 28 trillion tons of ice since 1994, research published Monday in The Cryosphere shows.
By Jewel Fraser
Noreen Nunez lives in a middle-class neighborhood that rises up a hillside in Trinidad's Tunapuna-Piarco region.