Shallow lakes located in dry landscapes face dramatic ecosystem changes caused by water loss and salinisation due to excessive water use and climate change. To understand the effects of these pressures on the ecology of lakes, we conducted a field survey across Anatolia and a synchronised mesocosm experiment in two climate zones in Türkiye. The field survey conducted over more than 40 lakes revealed a dramatic loss of biodiversity driven by salinisation and water loss, besides significant changes in lake ecosystem function across a large salinity gradient. We conducted two parallel long-term mesocosm experiments (September-2021 to May-2022), with 16 different salinities (0-50 g/L), in central and coastal Türkiye with different climatic conditions (temperate vs. subtropical). The salinity treatments were applied in three periods: increasing (30 days), stable (six months), and decreasing (40 days) salinities. Salinisation resulted in higher phosphorus and chlorophyll-a concentrations in the mesocosms, being more pronounced at salinities >20 g/L. Furthermore, salinisation significantly modified oxygen concentrations and turbidity contrastingly in different climate zones. Significant shifts in the community composition of plankton were observed over the salinity gradient with a loss of diversity. Overall, salinisation significantly impacted water quality, being also affected by climate. Both field surveys and mesocosm experiments revealed a predominant negative effects of water loss and salinisation on biodiversity, ecosystem metabolism, and, thus, on the ecosystem functioning of lakes.

Primary Presenter: Korhan Ozkan, Middle East Technical University (korhan.ozkan@gmail.com)

Authors:

Cihelio Alves Amorim,   ()

Gültekin Yılmaz,   ()

Mustafa Korkmaz, Institute of Marine Sciences, Middle East Technical University  (korkmaz.hidro@gmail.com)

Juan Pablo Pacheco,   ()

Gül Canan Yavuz,   ()

Vildan Acar,   ()

Yasemin Can,   ()

Meltem Koru,   ()

Can Özen,   ()

Zuhal Akyürek,   ()

Meryem Beklioğlu,   ()

Erik Jeppesen,   ()