MEPS 388:27-40 (2009)  -  DOI:

Effects of increased pCO2 and temperature on the North Atlantic spring bloom. II. Microzooplankton abundance and grazing

Julie M. Rose1,3, Yuanyuan Feng1,4, Christopher J. Gobler2, Robert Gutierrez2, Clinton E. Hare1, Karine Leblanc1,5,6, David A. Hutchins1,4,*

1College of Marine and Earth Studies, University of Delaware, 700 Pilottown Road, Lewes, Delaware 19958, USA
2School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794, USA
3Present address: Biology Department, MS #32, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, Massachusetts 02543, USA
4Present address: Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, California 90089, USA
5Present address: Aix-Marseille Université, CNRS, LOB-UMR 6535, Laboratoire d’Océanographie et de Biogéochimie, OSU/Centre d’Océanologie de Marseille, 163 Avenue de Luminy, 13288 Marseille Cedex 09, France
6Present address: CNRS (CNRS/INSU), UMR 6535, Campus de Luminy Case 901, 163 Avenue de Luminy, 13288 Marseille Cedex 09, France
*Corresponding author. Email:

ABSTRACT: The North Atlantic spring bloom is one of the largest annually occurring phytoplankton blooms in the world ocean. The present study investigated the potential effects of climate change variables (temperature and pCO2) on trophic dynamics during the bloom using a shipboard continuous culture system. The treatments examined were (1) 12°C and 390 ppm CO2 (ambient), (2) 12°C and 690 ppm CO2 (high pCO2), (3) 16°C and 390 ppm CO2 (high temperature), and (4) 16 °C and 690 ppm CO2 (greenhouse). Individually, increasing temperature and pCO2 initially resulted in significantly higher total microzooplankton abundance and grazing rates over the ambient treatment mid-experiment, with significantly greater increases still in the greenhouse treatment. By the end of the experiment, microzooplankton abundance was highest in the 2 low temperature treatments, which were dominated by small taxa, while the larger ciliate Strombidium sp. numerically dominated the high-temperature treatment. Microzooplankton community composition was dominated by small taxa in the greenhouse treatment, but total abundance declined significantly by the end after peaking mid-experiment. This decrease occurred concurrently with the growth of a potentially unpalatable phytoplankton assemblage dominated by coccolithophores. Our results suggest that indirect effects on microzooplankton community structure from changes in phytoplankton community composition as a result of changing temperature or pCO2 were likely more important than direct effects on microzooplankton physiology. Similar changes in trophic dynamics and whole plankton community composition may also be important for future climate-driven changes in the North Atlantic spring bloom assemblage.

KEY WORDS: Microzooplankton · Herbivory · Temperature · pCO2 · North Atlantic spring bloom · Climate change

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Cite this article as: Rose JM, Feng Y, Gobler CJ, Gutierrez R, Hare CE, Leblanc K, Hutchins DA (2009) Effects of increased pCO2 and temperature on the North Atlantic spring bloom. II. Microzooplankton abundance and grazing. Mar Ecol Prog Ser 388:27-40.

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