Researchers from University of British Columbia (UBC) are reporting an increase in the number of jellyfish populations in coastal areas of the world´s oceans. Many species are considered a nuisance when they sting swimmers. A larger concern is the damage they do to marine engines and power plants by clogging intakes. They are also a nuisance to fishermen
UBC scientists examined data for numerous species of jellyfish for 45 of the world´s 66 Large Marine Ecosystems. The researchers found increasing jellyfish populations in 62 percent of the regions analyzed, including East Asia, the Black Sea, the Mediterranean, the Northeast US Shelf, Hawaii, and Antarctica.
Lucas Brotz, a PhD student with the Sea Around Us Project at UBC and lead author of the study says, “There has been anecdotal evidence that jellyfish were on the rise in recent decades, but there hasn´t been a global study that gathered together all the existing data until now.”
“Our study confirms these observations scientifically after analysis of available information from 1950 to the present for more than 138 different jellyfish populations around the world.”
Daniel Pauly, the principal investigator of the project, said the expansion of human activity into marine habitats may be responsible for increasing jelly-fish populations. “We can also see that the places where we see rising numbers of jellyfish are often areas heavily impacted by humans through pollution, overfishing and warming waters.”
“By combining published scientific data with other unpublished data and observations, we could make this study truly global — and offer the best available scientific estimate of a phenomenon that has been widely discussed.”
Pauly adds that increasing anecdotal reports of jellyfish abundance may have resulted from an expansion of human activities in marine habitats, so the study also provides a concrete baseline for future studies, reports Gerry Bellett for the Vancouver Sun.
Also noted was a decrease in jellyfish abundance in seven percent of coastal regions, while the remainder of the marine ecosystems showed no obvious trend.
The study is published in this month´s edition of the journal Hydrobiologia.