MEPS 519:103-113 (2015)  -  DOI: https://doi.org/10.3354/meps11081

Some like it hot: the protozooplankton-copepod link in a warming ocean

N. Aberle1,*, A. M. Malzahn2, A. M. Lewandowska3,4, U. Sommer3

1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Biologische Anstalt Helgoland, Postfach 180,
27483 Helgoland, Germany
2Sultan Qaboos University, College of Agricultural and Marine Sciences, Dept. of Marine Sciences and Fisheries, PO Box 34,
123 Al-Khoud, Sultanate of Oman
3GEOMAR Helmholtz Centre for Ocean Research, Düsternbrooker Weg 20, 24105 Kiel, Germany
4Institute for Chemistry and Biology of the Marine Environment (ICBM-Terramare), Carl von Ossietzky University of Oldenburg, Schleusenstrasse 1, 26382 Wilhelmshaven, Germany
*Corresponding author:

ABSTRACT: The combined effects of warming and densities of overwintering copepods on the spring succession of Baltic Sea plankton were investigated using indoor mesocosms. Three zooplankton densities (1.5, 4 and 10 copepods l-1) and 2 temperature levels (Δ0°C and Δ6°C; 0°C and 6°C above present-day temperatures in the Kiel Bight) were chosen. Both the timing and the duration of the protozooplankton (PZP) bloom were significantly affected by temperature, but not by copepod density. In contrast, the bloom intensity of PZP was highly affected by the factors temperature and copepod density and their interaction. This suggests that under elevated temperature conditions PZP grows faster, but, at the same time, is subject to higher top-down control by copepods. At low temperatures and low copepod densities, PZP, in turn, fully escaped from copepod predation. Further changes in copepod overwintering densities resulted in a strong suppression of ciliates, of which small-sized ciliates (<30 µm) were especially vulnerable to copepod predation, while other PZP size classes remained unaffected. In conclusion, results point at a pivotal regulating role of overwintering copepods under future warming conditions. Further, warming was shown to cause a distinct match between phytoplankton and PZP, thus strengthening trophic pathways through PZP. Our findings are discussed in the context of the ‘trophic link-sink’ debate by considering potential alterations in the flux of matter and energy up the food web.


KEY WORDS: Climate change · Global warming · Protoperidinium bipes · Lohmaniella oviformis · Trophic sink · Trophic link · Zooplankton grazing · Trophic intermediary


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Cite this article as: Aberle N, Malzahn AM, Lewandowska AM, Sommer U (2015) Some like it hot: the protozooplankton-copepod link in a warming ocean. Mar Ecol Prog Ser 519:103-113. https://doi.org/10.3354/meps11081

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