Recent reports on jellyfish proliferation may be overstated
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.”