MEPS - Vol. 351 - Feature article

Jellyfish blooms that occur in eutrophic waters may increase the prevalence of red tides. Photo: M.J. Kingsford

Pitt KA, Kingsford MJ, Rissik D,
Koop K

 

Jellyfish modify the response of planktonic assemblages to nutrient pulses

 

Jellyfish exert top-down, while nutrients exert bottom-up control on plankton. Using mesocosms, Pitt and colleagues examined the response of planktonic communities to both blooms of jellyfish and nutrient enrichment processes. Bottom-up processes influenced 2 trophic levels, stimulating growth of phytoplankton and tintinnids. Top-down processes also cascaded to at least 2 trophic levels, as meso- and microzooplankton assemblages became depleted relative to controls. A unique finding was a 20-fold increase in concentrations of the red-tide-forming dinoflagellate Noctiluca scintillans in mesocosms that contained both jellyfish and nutrients, in contrast to mesocosms with nutrients or jellyfish alone. These results indicate that red tides may become more prevalent in the future if jellyfish blooms occur in coastal waters subject to nutrient enrichment.

 

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