Phytoplankton assemblage shifts with dissolved organic matter properties: A functional perspective for sentinel lakes

Climate change is altering both dissolved organic matter (DOM) properties and phytoplankton dynamics in lakes. High-altitude lakes are good sentinels of global change. However, their value as depends on how well we understand functioning. This study analysed physical, chemical biological data during three pre-defined periods running from complete ice-cover right to the end ice-free season, a high-altitude oligotrophic lake. A functional approach was used assess relationships between DOM planktonic community vary over time. Phytoplankton found occur with shifts DOM. During ice-influenced period, February thaw, dominated by small autotrophs mixotrophic flagellates sediment terrestrial origin pool diversity richness increased post-snowmelt overturn when pool. Finally, large siliceous autotrophs, competitive under low nitrogen concentrations high temperature, almost exclusively late summer period (LSP). Increased biomass meant that phytoplankton-derived dominant LSP. These phenological changes resulted at base food web. Based variables study, it can be deduced nature relationship bacteria progressively shifted strong top-down control exerted towards predominantly bottom-up season. Synthesis. Using field survey starting lasting season sentinel lake, show seasonal link plankton traits. Differences environmental conditions explained variation structure function, pointing microbial web interactions. Our research suggests that, climate change, balance mixotrophy autotrophy bacterioplankton will large, vegetated catchments.