THE IMPACT OF SALINIZATION AND WARMING ON SHALLOW LAKES THROUGH COLLABORATIVE RESEARCH BY EARLY-CAREER SCIENTISTS USING MESOCOSM STUDIES

Climate change and salinization are important threats to freshwater ecosystems, especially shallow lakes. To investigate the interactive effects of climate and salinity, we conducted three parallel mesocosm experiments in cold semiarid and warm Mediterranean Türkiye. Salinity was manipulated as a gradient (0-50 g/L) or as factorial treatments (4 and 40 g/L), combined with temperature treatments (ambient, heatwave, constant warming). In the first, an eight-month-long experiment with 16 different salinities (0-50 g/L), we found a unimodal response of key variables. Total nitrogen, phosphorus, chlorophyll a, alkalinity, and suspended solids increased with salinity. Water clarity peaked at 17 g/L, whereas it was lower at both low and high salinities in both climates. In the second experiment, lasting 8 weeks, we tested the impact of salinity (4 and 40 g/L) and a 2-week heatwave (+6 °C) across two climates. Higher salinity and a warmer climate enhanced phytoplankton biomass. The heatwave had negligible effects on key variables. The third experiment highlighted the stronger influence of higher temperature (+4.5 °C) on oxygen concentration, pH, and alkalinity, particularly in warmer climates and at salinity 40 g/L. All of these were made possible through the collaboration of more than 40 volunteers, interns, MSc and PhD students, supported by METU and TÜBİTAK, as well as 19 researchers supported by the EU-H2020 AQUACOSM-plus project. In conclusion, salinization is a critical stressor in shallow lakes, with its effects modulated by climate and temperature.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Cihelio Amorim, Federal Rural University of Pernambuco, WasserCluster Lunz and Middle East Technical University (alvescihelio@gmail.com)

Authors:

Cihelio Alves, Middle East Technical University, WasserCluster Lunz and Middle East Technical University  (alvescihelio@gmail.com)

Gültekin Yılmaz, University of Nebraska–Lincoln  (tekin.ims@gmail.com)

İrem Gamze Arık, Middle East Technical University  (igamzearik@gmail.com)

Mustafa Korkmaz, Middle East Technical University  (korkmaz.hidro@gmail.com)

Meltem Koru, Middle East Technical University  (korumeltem99@gmail.com)

Zeynep Uyar, Middle East Technical University  (zeyneppuyarr84@gmail.com)

Md Masum Billah, Middle East Technical University  (masum_imsf07@yahoo.com)

Arjete Brahusha, Middle East Technical University  (arjetebrahusha@gmail.com)

Onat Arıkan, Middle East Technical University  (arikan.onat@metu.edu.tr)

Canan Yavuz, Middle East Technical University  (gcy.2137@gmail.com)

Korhan Özkan, Middle East Technical University  (okorhan@metu.edu.tr)

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

Erik Jeppesen, Aarhus University and Middle East Technical University  (ej@ecos.au.dk)