Methodological design to study the effects of heatwaves on natural plankton communities from Mediterranean vulnerable ecosystems

The Mediterranean region is considered one of the areas most exposed to climate warming, with artificial lakes and coastal lagoons representing particularly vulnerable ecosystems, that provide essential goods and services. Among the extreme events linked to warming, heatwaves are of growing concern, yet their ecological effects on the functioning of Mediterranean aquatic systems remain poorly investigated. We present a methodological framework designed by the Project “a warmer Future world: effects on plankton commUnities and paThogens in mediterranean vUlneRable Ecosystems (FUTURE) ” to study how natural plankton communities respond to abrupt and sustained thermal stress. The approach focuses on entire communities, from bacteria to zooplankton, includes laboratory experiments and field monitoring activities, and combines classical techniques with molecular tools to capture changes in biodiversity, food web size-structure, and the occurrence of potentially pathogenic and antibiotic-resistant bacteria. Two diverse aquatic ecosystems in the Western Mediterranean were selected as case studies: an artificial lake used for drinking water and a coastal lagoon used for fishery, both of high ecological and economic importance. By applying controlled experimental simulations with ecological relevance, the framework provides a replicable approach to investigate plankton community-level responses to heatwaves. This methodological contribution aims to support future research by offering a comparative perspective on vulnerable Mediterranean ecosystems and promoting standardized approaches to assess the impacts of extreme climate-driven events. By providing a scalable and reproducible protocol, this work contributes to filling a critical knowledge gap in the Mediterranean and supports future research and management efforts in climate-sensitive aquatic ecosystems.