Cascading effects of the ctenophore Mnemiopsis leidyi on the planktonic food web in a nutrient-limited estuarine system
Dinasquet, Julie; Titelman, Josefin; Møller, Lene Friis; Setala, Outi; Granhag, Lena M.; Andersen, Thorvin; Båmstedt, Ulf; Haraldsson, Matilda; Hosia, Aino; Katajisto, Tarja; Kragh, Theis; Kuparinen, Jorma; Schrøter, M.-L.; Søndergaard, Morten; Tiselius, Peter; Riemann, Lasse
Journal article, Peer reviewed
Permanent lenke
http://hdl.handle.net/11250/109228Utgivelsesdato
2012-07-24Metadata
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Originalversjon
http://dx.doi.org/10.3354/meps09770Sammendrag
Increasing biomasses of gelatinous zooplankton presumably have major implications
for the structure and function of marine food webs at large; however, current data on lower trophic
levels are scarce, as most studies have focused on the immediate effects on zooplankton and fish
larvae only. We examined the short-term impact of larvae and adults of the invasive ctenophore
Mnemiopsis leidyi on a summer planktonic food web in the estuarine southern Baltic Sea, with
special emphasis on the microbial loop. Grazing by M. leidyi reduced the mesozooplankton biomass,
followed by increased dinoflagellate biomass in treatments with M. leidyi. While chlorophyll
a increased most in the treatments with M. leidyi, small phytoplankton and ciliates
decreased in all treatments. M. leidyi had a slight effect on bacterial abundance, but not on bacterial
production, ectoenzymatic activities, or community composition. Undetectable levels of
phosphate and a gradual accumulation of dissolved organic carbon during the experiment suggested
a malfunctioning microbial loop scenario. The experiment shows that direct and indirect
short-term effects of M. leidyi on the estuarine food web are limited to higher trophic levels and
indicates that top-down and bottom-up consequences of M. leidyi expansions on the microbial
loop will likely depend on local nutrient conditions.