Climate change is causing biodiversity loss at unprecedented rates threatening ecological stability and human welfare. Freshwater ecosystems (e.g. ponds, lakes, rivers) are particularly vulnerable since their relatively discrete ecosystem boundaries constrain species’ potential to respond to climate change (e.g. warming, drought). Predicting such responses remains a challenge because most research is still focused on individual species and rarely generalized across different scales and climatic conditions. To advance our understanding about how natural systems respond to climate change it is crucial to find ways to reconcile research at individual, food-web and ecosystem-level. Ecophysiological studies measuring how organisms adapt to environmental conditions have demonstrated the crucial role of temperature in constraining species distributions. Ecological networks, such as aquatic food webs, are reorganizing as a result of such distributional shifts. In particular, increased temperatures have negative impacts on higher trophic levels (e.g. predatory fish) with cascading effects on food-web structure (e.g. what-eats-what) and vital ecosystem services (e.g. detrital decomposition, carbon sequestration, nutrient recycling). The potential loss of higher trophic levels is particularly crucial in freshwater systems (e.g. Alqueva reservoir) since it can enhance greenhouse gas (GHG) emissions (e.g. CO2, CH4), leading to further global warming (>20% of global CH4 emissions originate in freshwater systems). Thus, unravelling the links between changes in food web structure and GHG emissions is critical to be able to predict how aquatic ecosystems respond to change, but also how much they are contributing to such change. AdaptAlentejo – Predicting ecosystem-level responses to climate change – will help address this gap in knowledge by combining multiple disciplines (physiology, biogeochemistry and geophysics) and state-of-art tools (e.g. metagenomics; complex networks, carbon flux measurements). Specific objectives include:

• Quantify species’ physiological responses to increasing temperatures;
• Quantify energy flows (e.g. what-eats-what) within aquatic food-webs to assess ecological resilience to change;
• Test ecosystem-level responses using a combination of biodiversity surveys; experimental mesocosms and whole-ecosystem (i.e. reservoirs) manipulations.