Salinization and warming effects on zooplankton community in Mediterranean shallow lakes: a mesocosm experiment

Freshwater ecosystems in the Mediterranean climate zone are increasingly threatened by declining precipitation and rising evaporation, which reduce lake volumes, flushing out and in turn increase salinity. The effects of warming and salinity are often studied separately, while their combined influence is poorly understood. We elucidated how zooplankton communities respond to the combined effects of salinity and warming under future climate scenarios. A three-month mesocosm experiment was conducted in fall 2023 in Mediterranean Türkiye, applying two salinity levels (4 g/L and 40 g/L) crossed with two temperature treatments (ambient temperature and +4.5°C warming). Results showed a difference in community composition between salinity treatments. At 4 g/L, large-bodied cladocerans dominated the zooplankton community, whereas 40 g/L mesocosms were dominated by halotolerant small-bodied rotifers. Diversity and richness were consistently higher under low salinity treatment. PERMANOVA results indicated that warming had no significant effect on biomass. GAM analyses revealed salinity in combination with warming predominantly led to reduced zooplankton diversity with an additional small but significant non-linear effect of water clarity. The model explained 66% of the variation in Shannon diversity. Overall, our findings emphasize that increasing salinization, particularly with warming, may impoverish zooplankton community structure and induce major shifts in zooplankton community composition in Mediterranean lakes.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Meltem Kuyumcu, Middle East Technical University (korumeltem99@gmail.com)

Authors:

Meltem Kuyumcu, 1 Institute of Marine Sciences, Middle East Technical University, 33731, Erdemli, Mersin, Türkiye  (korumeltem99@gmail.com)

Gültekin Yılmaz, 2 School of Natural Resources, University of Nebraska-Lincoln, 68583, Lincoln, Nebraska, the United States.  (tekin.ims@gmail.com)

Cihelio Amorim, 3 Limnology Laboratory, Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Türkiye 4 WasserCluster Lunz – Biologische Station GmbH and University for Continuing Education – Danube University Krems, Lunz am  (alvescihelio@gmail.com)

Mustafa Korkmaz, 1 Institute of Marine Sciences, Middle East Technical University, 33731, Erdemli, Mersin, Türkiye 3 Limnology Laboratory, Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Türkiye5 Centre for Ecosystem Research (EKOSAM), Middle East Technical University, 06800, Ankara, Türkiye  (korkmaz.hidro@gmail.com)

Onat Arıkan, 1 Institute of Marine Sciences, Middle East Technical University, 33731, Erdemli, Mersin, Türkiye  (nakiratano@gmail.com)

Masum Billah, 1 Institute of Marine Sciences, Middle East Technical University, 33731, Erdemli, Mersin, Türkiye  (masum_imsf07@yahoo.com)

Gül Yavuz, 3 Limnology Laboratory, Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Türkiye  (gcy.2137@gmail.com)

İrem Arık, 3 Limnology Laboratory, Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Türkiye  (igamzearik@gmail.com)

Meryem Beklioğlu, 3 Limnology Laboratory, Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Türkiye 5 Centre for Ecosystem Research (EKOSAM), Middle East Technical University, 06800, Ankara, Türkiye  (meryem@metu.edu.tr)

Erik Jeppesen, 3 Limnology Laboratory, Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Türkiye 1 Institute of Marine Sciences, Middle East Technical University, 33731, Erdemli, Mersin, Türkiye 5 Centre for Ecosystem Research (EKOSAM), Middle East Technical University, 06800, Ankara, Türkiye6 Department of Ecoscience, Aarhus University, 8000, Aarhus, Denmark 7 Sino-Danish Centre for Education and Research (SDC), Beijing, People’s Republic of China 8 Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, People’s Republic of China  (ej@ecos.au.dk)

Korhan Özkan, 1 Institute of Marine Sciences, Middle East Technical University, 33731, Erdemli, Mersin, Türkiye 5 Centre for Ecosystem Research (EKOSAM), Middle East Technical University, 06800, Ankara, Türkiye  (korhan.ozkan@gmail.com)