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Study eyes global jellyfish populations

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Are jellyfish numbers increasing globally? One recent study suggests decadal fluctuations. Photo courtesy NOAA.

More long-term and widespread monitoring needed to pinpoint trends

By Summit Voice

FRISCO —Global jellyfish populations appear to fluctuate on a decadal basis, including an increase in the 1990s and early 2000s that has led to the current perception of an overall global increase in jellyfish abundance.

But reports that jellyfish are steadily increasing may be unfounded, according to a recent study led by researchers from the Dauphin Island Sea Lab in Alabama and the National Oceanography Centre, Southampton, UK, who concluded there is no robust evidence for a global increase in jellyfish over the past two centuries.

The researchers did find a hint of a slight increase in jellyfish since 1970, although this trend was countered by the observation that there was no difference in the proportion of increasing vs. decreasing jellyfish populations over time. Continue reading

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Jellyfish numbers growing in many coastal ecosystems

Study finds increased abundance in areas affected by human development

Map of population trends of native and invasive species of jellyfish by Large Marine Ecosystems. Red: increase (high certainty); orange: increase (low certainty); green stable/variable; blue decrease, grey: no data. Circles represent jellyfish populations with relative sizes reflecting confidence in the data. (Brotz et al, Hydrobiologia).

Giant jellyfish (Nemopilema nomurai) interfere with fishing in Japan. PHOTO COURTESY SHIN-ICHI UYE.

By Bob Berwyn

SUMMIT COUNTY — Jellyfish populations are growing  in  many of the world’s coastal ecosystems, especially in areas affected by pollution, overfishing, and warming waters, according to a new study done by researchers with the University of British Columbia.

“We found numerous types and species of jellyfish that appear to be increasing, so the reported increases are certainly not due to one type jellyfish in particular,” said Lucas Brotz, a PhD student with the Sea Around Us Project at UBC and lead author of the study.

“That being said, there are several species of jellyfish that appear to be highly invasive are invading new regions around the globe all the time (probably due to transport from cargo ships),” Brotz said via email. ” The most notorious of these is a comb jellyfish called Mnemiopsis leidyi which is showing up in new places every year and often rapidly increases in abundance, potentially altering the ecosystems it invades,” he said. Continue reading

Summit Voice: Most-viewed & week in review

A lion's mane jellyfish. PHOTO BY DAN HERSHMAN VIA THE CREATIVE COMMONS.

Jellyfish, weather and avalanches

By Summit Voice

SUMMIT COUNTY — A decent week for page views at Summit Voice, with a Google News link for our jellyfish story driving page views to more than 6,000. It’s the first time we can remember that we’ve had four stories with 1,000 page views or more, including a couple of climate science articles and a quick blurb on the Front Range snow storm. Click, read and share with the social media buttons at the end of each post.

Environment: Jellyfish may get last dance

New study suggests jellyfish proliferation could discombobulate ocean food chain. Photo courtesy Anna Fiolek, NOAA Central Library.

Balance of ocean food web at risk as jellyfish blooms increase

By Summit Voice

SUMMIT COUNTY — Warmer water temperatures, over-fishing and nutrient loading in coastal areas could result in a jellyfish takeover, according to a team of biologists who studied the role of the slimy floaters in marine ecosystems.

The scenario might be good for a jellyfish lover like the cartoon character Spongebob Squarepants, but as numbers of jellyfish increase, they could tip the balance of ocean food chains away from fish and toward bacteria, the scientists with the Virginia Institute of Marine Science wrote in a paper recently published in the Proceedings of the National Academy of Sciences.

Jellyfish eat huge amounts of plankton, which is also the most important food for small fish at the base of ocean food chains. But jellyfish are not a significant food source for other animals and their waste products add almost nothing useful to marine ecosystems. Continue reading

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