MEPS 357:195-206 (2008)  -  DOI:

Determination of copepod grazing on natural plankton communities: correcting for trophic cascade effects

Christine Klaas1,*, Peter G. Verity2, Sabine Schultes1,3

1Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
2Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, Georgia 31411, USA
3Present address: LEMAR, Institut Universitaire Européen de la Mer, Place Nicolas Copernic, Technopole Brest Iroise,
29280 Plouzané, France

ABSTRACT: Grazing rates and grazing selectivity of Antarctic copepods (Rhincalanus gigas, Calanus simillimus and copepods 0.8 to 2 mm in size) were determined using incubation experiments comparing plankton community development with and without added grazers. Estimates of grazing rates were corrected for trophic cascade effects using a simple ecosystem model composed of 5 compartments: (1) nanophytoplankton, (2) nanozooplankton, (3) microphytoplankton, (4) microzooplankton (mainly protozoans) and (5) copepods. Copepod grazing rates on the different planktonic compartments were derived by solving for model parameters as constrained by microscopy enumeration of nano- and microphytoplankton and nano- and microprotozooplankton in treatments with and without added copepods. Simulations based on different parameter values and model configurations support the notion that grazing estimates were robust and between 18 and 30% higher than uncorrected estimates. Furthermore, model analyses suggest the presence of an additional trophic cascade effect due to grazing of R. gigas on small copepods and copepod developmental stages present in incubation bottles.

KEY WORDS: Ecosystem model · Zooplankton · Copepod grazing · Southern Ocean · Rhincalanus gigas · Calanus simillimus

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Cite this article as: Klaas C, Verity PG, Schultes S (2008) Determination of copepod grazing on natural plankton communities: correcting for trophic cascade effects. Mar Ecol Prog Ser 357:195-206.

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