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Recent reports on jellyfish proliferation may be overstated
Researchers hope to unravel some jellyfish mysteries with a global monitoring project. PHOTO COURTESY ANNA FIOLEK, NOAA.
By Summit Voice
SUMMIT COUNTY — Much to SpongeBob’s chagrin, reports that jellyfish are taking over the world’s oceans may be exaggerated and unsupported by any hard evidence or scientific analyses, according to a research team with expertise on gelatinous organisms.
A new global collaborative study conducted at UC Santa Barbara’s National Center for Ecological Analysis and Synthesis suggests that jellyfish populations fluctuate on a decadal scale, but that more research is needed to determine whether there are other factors in play, and whether there are long-term trends on a global or regional scale.
The researchers don’t deny that blooms of jellyfish have clogged fising nets and choked intake lines for power plants. But they say that widespread reporting of those incidents has created a perception that the world’s oceans are experiencing increases in jellyfish due to human activities such as global warming and over-harvesting of fish.
The study was led by Rob Condon, a marine scientist at the Dauphin Island Sea Lab in Alabama. It appears in the latest issue of the journal BioScience.
“Clearly, there are areas where jellyfish have increased — the situation with the giant jellyfish in Japan is a classic example,” Condon said. “But there are also areas where jellyfish have decreased, or fluctuate over the decadal periods.” Condon said understanding the long-term rather than short-term data is the key to solving the question about jellyfish blooms.
In a previous study, Condon looked at two species of jellyfish in the York River, flowing into Chesapeake Bay, and observed a significant top-down changes to the zooplankton community. He found that blooms of several species are causing major problems for marine food webs and human activities, and that their increased presence in Baltic and Mediterranean seas suggest that jellyfish have significant invasive potential.
“There are major consequences for getting the answer correct for tourism, fisheries and management decisions as they relate to climate change and changing ocean environments,” said Carlos Duarte, of the University of Western Australia’s Oceans Institute. “The important aspect about our synthesis is that we will be able to support the current paradigm with hard scientific data rather than speculation.”
The study highlights the formation of a global database called the Jellyfish Database Initiative (JEDI) — a community-based database project that is being used in the global analysis and to test the worthiness of the current paradigm. The database consists of over 500,000 data points about global jellyfish populations collected from as early as 1790, and will serve as a future repository for datasets so that the issue of jellyfish blooms can be continually monitored in the future.
By analyzing JEDI, the group will be able to assess key aspects behind the paradigm, including whether current jellyfish blooms are caused by human-made actions or whether we are simply more aware of them due to their impact on human activities, such as over-harvesting of fish and increased tourism.
“This is the first time an undertaking of this size on the global scale has been attempted, but it is important to know whether jellyfish blooms are human-induced or arise from natural circumstances,” said Condon. “The more we know, the better we can manage oceanic ecosystems or respond accurately to future effects of climate change.”
Filed under: biodiversity, climate and weather, Environment, Summit County news Tagged: | BioScience, Dauphin Island Sea Lab, National Center for Ecological Analysis and Synthesis
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I thought it has been reported widely that jellyfish “blooms” or vast increases in their numbers is due to their ability to live in the “dead zones” created offshore of populated and agricultural zones. These dead zones are hundreds of square miles and exist off shore where most industrialized human populations are found and are most certainly human created (primarily agricultural pollution/fertilizer run-off); the organization NOAA has documented this assertion as accurate, as well as many others. Apparently where most other life can not survive in the oxygen deprived “dead zones” jellyfish thrive, and are even become a new abundant source of food in chinese markets….yuck.
….so this article and its scientific references seem to missing much….
I’ve lived in Florida most of my life, since 1948 and this past year I’ve never seen anything even close to the huge numbers of moon jellyfish that have been around for about 6-8 months. Not only that, but they have shown intelligence by grouping together even despite current. My friend and I were diving one day and when we decided to come up, the jellyfish had gathered behind my boat possibly, I thought, because of the generator that was running at the stern. Reminded my of Hitchkoch’s “the birds”. It’s really pretty scary to me.
Isn’t that picture upside down?
To clarify (in case it gets inverted quietly): the version of the picture on which I’m commenting has most of the jellies depicted with their oral (dangly parts) up, and the aboral (smooth cap) down.
They swim every which way. Note one in top right is swimming horizontally so this could easily be right side up.
And in aquariums, where the water is circulating, I’ve often seen them swim in what looks like the upside-down position.
So journalism now consists of repeating press releases, with no skepticism or journalistic investigation at all? Color me disappointed.
Dauphin Island Sea Lab takes money from Big Oil. As in, a *lot* of money. Their last check from BP was a cool 5 million dollars. Now Dauphin Island is defending a viewpoint that is bound to please Big Oil and other emitters of toxins and CO2: ‘nothing to see here, move along.’
The first place to look to see if that is true is the Mediterranean: this is the sea which has sustained the most prolonged influences from humans (pollution and overfishing). It’s pretty well established that vertebrate species there have badly crashed and jellyfish are on a sharp upward trajectory that cannot be explained in terms of decadal cycles. The other oceans haven’t shown trending to the same extent, but there’s enough going on to be worrisome.
Between the effects of industrial toxins, acidification of oceans (rising CO2 content) and overfishing, the crash of vertebrate species in the world’s oceans may open opportunities for inedible (to humans) invertebrate species, especially jellyfish. There are jellyfish cycles, certainly, but proving there are cycles does nothing to prove that there are no long-term trends manifesting due to human agency.
Some oceanographers are predicting that world ocean stocks of edible fish will no longer exist in commercially significant quantities by the year 2050. They’ll be dead: humans will have consumed them, or toxins will have killed or weakened them and opened them up to opportunistic diseases, or their food supplies will dwindle due to acidification. Some fish species – not all in the Mediterranean – are already distressed or moving towards extinction, and this is often reflected in the enthusiastically high price of their flesh in Asian markets (bluefin tuna, for example). Ocean biomass may very well be shifting away from vertebrates and towards invertebrates; though more study is definitely needed, at present the only way to broadly conclude there is no evidence of ocean invertebrates supplanting vertebrates is to focus narrowly on data that supports this view and ignore all of the rest. This is called “cherry-picking” and it’s not acceptable science.