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Erik Jeppesen

Size-based interactions across trophic levels in food webs of shallow Mediterranean lakes

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DOI

  • Sandra Brucet
  • ,
  • Ulku Nihan Tavsanoglu, Middle East Technical University
  • ,
  • Arda Ozen, Cankiri Karatekin Univ, Cankiri Karatekin University, Dept Forest Engn
  • ,
  • Eti Ester Levi, Middle East Technical University
  • ,
  • Gizem Bezirci, Middle East Technical University
  • ,
  • Ayse Idil Cakiroglu, Middle East Technical University
  • ,
  • Erik Jeppesen
  • Jens-Christian Svenning
  • Zeynep Ersoy, Aquat Ecol Grp, Univ Vic Cent Univ Catalonia, Middle E Tech Univ, Orta Dogu Teknik University, Dept Biol, Limnol Lab, Middle East Tech Univ, Middle East Technical University
  • ,
  • Meryem Beklioglu, Middle East Technical University

1. Body size is a key trait of an organism which determines the dynamics of predator-prey interactions. Most empirical studies on the individual size distribution of the aquatic community have focused on the variations in body size of a single trophic level as a response to certain environmental variables or biotic factors. Few studies, however, have evaluated how individual size structure is altered simultaneously across interacting trophic levels and locations. Such comparative examinations of the size distribution in predator and prey communities may bring insight into the strength of the interactions between adjacent trophic levels.

2. We assessed the potential predation effect of size-structured predators (i.e. predation by individuals of different sizes) on prey size structure using data from 30 shallow Turkish lakes spanning over five latitudinal degrees. We correlated size diversity and size evenness of predator and prey assemblages across the planktonic food web after accounting for the confounding effects of temperature and resource availability which may also affect size structure. We expected to find a negative relationship between size diversity of predators and prey due to the enhanced strength of top-down control with increasing predator size diversity. We also hypothesised that competitive interactions for resources in less productive systems would promote a higher size diversity. We further expected a shift towards reduced size diversity and evenness at high temperatures.

3. In contrast to our hypothesis, we found a positive correlation between size structures of two interacting trophic levels of the planktonic food web; thus, highly size-diverse fish assemblages were associated with highly size-diverse zooplankton assemblages. The size evenness of fish and phytoplankton assemblages was negatively and positively related to temperature, respectively. Phytoplankton size diversity was only weakly predicted by the resource availability.

4. Our results suggest that size structure within a trophic group may be controlled by the size structure at adjacent trophic levels, as well as by temperature and resource availability. The positive relationship between the size diversity of fish and zooplankton suggests that higher diversity of the resources drives a higher size diversity of consumers or vice versa, and these effects are beyond those mediated by taxonomic diversity. In contrast, the size diversity and size evenness of phytoplankton are mainly influenced by physical factors in this region and perhaps in warm shallow lakes in general.

Original languageEnglish
JournalFreshwater Biology Online
Volume62
Issue11
Pages (from-to)1819-1830
Number of pages12
ISSN0046-5070
DOIs
Publication statusPublished - Nov 2017

    Research areas

  • fish, phytoplankton, predator-prey interactions, size diversity, zooplankton, BODY-SIZE, CLIMATE-CHANGE, CONTRASTING TEMPERATURES, PREDATOR DIVERSITY, ECOSYSTEM FUNCTION, FISH COMMUNITIES, PHYTOPLANKTON, SPECTRA, ECOLOGY, PREY

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