Copepods act as switch between alternative trophic cascades in marine pelagic food webs.

Stibor, H. , Vadstein, O. , Diehl, S. , Gelzleichter, A., Hansen, Thomas, Hantzsche, F. , Katechakis, A. , Lippert, B., Loeseth, K. , Petersen, Christer, Roederer, W. , Sandow, Marcel, Sundt-Hansen, L. and Olsen, Y. (2004) Copepods act as switch between alternative trophic cascades in marine pelagic food webs. Ecology Letters, 7 (4). pp. 321-328. DOI 10.1111/j.1461-0248.2004.00580.x.

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Abstract

A recent meta-analysis indicates that trophic cascades (indirect effects of predators on plants via herbivores) are weak in marine plankton in striking contrast to freshwater plankton (Shurin et al. 2002, Ecol. Lett., 5, 785–791). Here we show that in a marine plankton community consisting of jellyfish, calanoid copepods and algae, jellyfish predation consistently reduced copepods but produced two distinct, opposite responses of algal biomass. Calanoid copepods act as a switch between alternative trophic cascades along food chains of different length and with counteracting effects on algal biomass. Copepods reduced large algae but simultaneously promoted small algae by feeding on ciliates. The net effect of jellyfish on total algal biomass was positive when large algae were initially abundant in the phytoplankton, negative when small algae were dominant, but zero when experiments were analysed in combination. In contrast to marine systems, major pathways of energy flow in Daphnia-dominated freshwater systems are of similar chain length. Thus, differences in the length of alternative, parallel food chains may explain the apparent discrepancy in trophic cascade strength between freshwater and marine planktonic systems.

Document Type: Article
Keywords: Indirect effects; meta-analysis; predation; top-down control; trophic structure; food chain theory
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-N Experimental Ecology - Food Webs
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1111/j.1461-0248.2004.00580.x
ISSN: 1461-023X
Date Deposited: 11 Feb 2010 14:28
Last Modified: 27 Feb 2019 12:30
URI: http://oceanrep.geomar.de/id/eprint/244

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