DRIVERS OF ZOOPLANKTON BODY SIZE IN PONDS ACROSS BROAD SPATIAL SCALES

Body size is a fundamental trait influencing ecological functions, trophic dynamics and organismal fitness across ecosystems. However, the environmental drivers shaping body size patterns in pond ecosystems across broad spatial scales remain poorly defined. We assessed how latitude, food availability and predation influence individual body size in cladocerans and copepods, as well as the size structure of the entire zooplankton community. Zooplankton was sampled using standardized protocols in 141 ponds across four European countries and Uruguay. Our findings indicate that latitude and predation are major selective forces shaping crustacean individual body size in ponds. Individual mean body size increased with latitude for both taxa, supporting the temperature-size rule, while fish presence was associated with smaller body sizes. In contrast, the entire zooplankton community size structure was mainly shaped by local factors and did not significantly differ along the climatic gradient. Steeper size spectra with increasing chlorophyll‑a concentrations reflected dominance of small-sized zooplankton. This suggests reduced energy transfer efficiency to higher trophic levels and weaker top-down control on phytoplankton in more eutrophic conditions. Conversely, flatter slopes at lower chlorophyll-a concentrations suggest a greater contribution of larger zooplankton and stronger top-down control. The overall intercept of size spectra was higher in deeper, vegetated ponds, indicating higher total zooplankton abundance. These results highlight the value of size-based approaches for understanding pond food-web functioning and their responses to environmental stressors.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Sandra Brucet, University of Vic & ICREA (sandra.brucet@uvic.cat)

Authors:

Sandra Brucet, University of Vic & ICREA  (sandra.brucet@uvic.cat)

Katterine Rincon-Palau, Bionexus Foundation  (katterine.rincon@fundaciobionexus.org)

Feride Avci, Middle East Technical University  (ferideavci18@gmail.com)

Mireia Bartrons, University of Vic  (mireia.bartrons@uvic.cat)

Meryem Beklioglu, Middle East Technical University  (meryem@metu.edu.tr)

Dani Boix, University of Girona  (dani.boix@udg.edu)

Carmela Carballo, Universidad de la República  (ccarballo@fcien.edu.uy)

María Cuenca-Cambronero, University of Vic  (maria.cuenca@uvic.cat)

Thomas Davidson, Aarhus University  (thd@ecos.au.dk)

Victoria Frutos-Aragón, University of Vic  (victoria.frutos@uvic.cat)

Gissell Lacerot, Universidad de la República  (glacerot@gmail.com)

Pieter Lemmens, KU Leuven  (pieter.lemmens@inbo.be)

Luís Martín, University of Girona  (luis.martin@udg.edu)

Mariana Meerhoff, Universidad de la República  (mm@ecos.au.dk)

Thomas Mehner, Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)  (thomas.mehner@igb-berlin.de)

Robby Wijns, KU Leuven  (robby.wijns@kuleuven.be)

Anna Badosa, Central University of Catalonia  (anna.badosa@uvic.cat)