Jellyfish ‘may benefit from ecosystem instability’

By Mark Kinver Science and environment reporter, BBC News
29 October 2010 A team of researchers have been trying to identify how jellyfish may benefit from marine ecosystems destabilised by climate change and overfishing.

There is concern that a rise in jellyfish numbers could prevent depleted commercially important fish stocks recovering to historical levels. However, a study by European scientists says more data is needed to understand what is happening beneath the waves. The findings are set to be published in the journal Global Change Biology. Researchers from the UK and Ireland said samples collected from the Irish Sea since 1970 have recorded an increase in material from cnidarians (the division of the animal kingdom that includes jellyfish and coral), “with a period of frequent outbreaks between 1982 and 1991”. “There does appear to have been an increase in abundance since 1994 for the Irish Sea,” said co-author Christopher Lynam, a researcher at the Centre for Environment Fisheries and Aquaculture Science (Cefas). The team added that previous studies had recorded changes to marine ecosystems as a result of various factors, such as the removal of top predators, and changes to the distribution and characteristics of plankton. … He explained that the team looked at whether factors such as changes to the climate and overfishing were responsible for the increase in jellyfish abundance. “It is quite a complicated set of possible linkages that need to be drawn, which we really only have a vague insight at the moment. “For the recent period where we have good data, it appears as if sea surface temperature is the most important variable. “This does not necessarily prove it of course, but it does appear to be benefiting jellyfish.” The team, using data provided by the UK Met Office, commented: “The regional seas of the northeast Atlantic have been warming for the past 15 years at a rate not experienced in recent centuries.” …