Wednesday, June 8, 2011

Jellyfish blooms endanger ocean food chain

Greg Dash in Cosmos: Jellyfish blooms, consisting of thousands of swarming individuals, induce major changes in the food chain, a study has found. Climate change and overfishing have been blamed for the increase in blooms. With greater numbers of jellyfish to feed, the blooms result in a major decrease in resources available to fish. Plus a bacterial bloom often accompanies a jellyfish bloom, and this will feed on and respire the dissolved organic matter excreted by the feeding jellies, further restricting the available resources.

Both of these processes lock up carbon from the environment, storing it in inedible gelatinous biomass or dissolved carbon dioxide. "Jellyfish are voracious predators," said lead author Rob Condon of the Dauphin Island Sea Lab (DISL) in Alabama, U.S. "They impact food webs by capturing plankton that would otherwise be eaten by fish and converting that food energy into gelatinous biomass. This restricts the transfer of energy up the food chain, because jellyfish are not readily consumed by other predators."

The new study, published in the current issue of the Proceedings of the National Academy of Science, represents a breakthrough in our understanding of the effect of jellyfish blooms on marine ecology. Although some understanding on the relationship between jellyfish and microbial blooms existed previously, for the first time scientists were able to overcome the difficulties in quantifying this relationship….

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