Unravelling nutrient dynamics in Sierra Nevada lakes through sediment-water interactions

Resumen

Global change stressors are anticipated to trigger eutrophication and deteriorate water quality in high mountain lakes. To accurately predict the future of these vulnerable aquatic systems, research must adopt a holistic approach that integrates sediment-water interactions–processes often underestimated in oligotrophic high mountain lakes compared to external drivers. This paper provides a historical review of the primary chemical, physical, and biological mechanisms governing sedimentary phosphorus (P) mobilization and highlights how these dynamic interactions are influenced by global change. Subsequent sections focus on two Sierra Nevada lakes (Río Seco and Lake La Caldera, Granada, Spain) with contrasting watershed and hydrological characteristics to assess how desiccation and re-flooding influence sedimentary P dynamics, and water quality. Furthermore, the study explores sedimentation and resuspension processes, emphasizing their crucial role in coupling planktonic and benthic communities. Lake desiccation decreases sedimentary P adsorption capacity due to the reduction in fine mineral fractions (rich in iron and aluminium oxides) and organic matter. Long-term data from Lake La Caldera over 20 years confirm significant P increases in lake water during droughts. Overall, understanding how water level fluctuations (WLFs) influence the biogeochemistry in these high-mountain lakes, and Mediterranean wetlands more broadly, is pivotal for accurately forecasting the responses of inland waters within the evolving global change scenario.