About

Climate change is recognized as a major threat to global biodiversity, but there is uncertainty about the extent at which climate change will impact biodiversity, ecosystem services, and the thresholds above which ecosystems are irreversibly changed. Freshwater ecosystems are biologically rich and play major roles in providing ecosystem services, but they are mostly altered and vulnerable to the impacts of climate change.

Early research on Biodiversity and Ecosystem Functioning (B-EF) has tested for effects of plant species richness on primary productivity in grassland ecosystems. As the majority of primary production enters detrital food webs, B-EF studies have expanded into detritus-based ecosystems to better understand the importance of biodiversity on decomposition and nutrient cycling. Decomposition of allochthonous plant-litter is a key ecosystem process in freshwaters that depends on the riparian vegetation and the decomposer communities, namely fungi, bacteria and invertebrate shredders. This creates a strong unidirectional link between terrestrial primary producers and the aquatic consumers making stream detritus-based food-webs ideal systems to explore B-EF relationships.

In the STREAMECO (PTDC/CTA-AMB/31245/2017), we will use plant litter decomposition, fungal decomposers and invertebrate detritivores as a model system to assess impacts of climate change in streams. We aim to predict how biodiversity, ecosystem functions and services respond to multiple stressors related to climate change (warming, drought and nutrient enrichment) and further contribute to a better management of stream ecosystems.

Experiments will be conducted in field and mesocosms because mesocosm simplicity allows a high degree of control and replication. We will include in silico studies in an attempt to overcome the practical constrains of single experiments.

First, we will i) establish phylogenetic relationships between fungi, and ii) develop molecular probes to target key genes involved in the degradation of plant litter to distinguish functional traits within communities. Then, we will run a long-term mesocosm experiment with natural benthic communities, which will be exposed to increasing levels of climate change related stressors. This will allow us to identify the most vulnerable taxa and functions to climate change.

To clarify the impacts of diversity loss under climate change related stressors, we will use a multispecies mesocosm experiment in which diversity loss will be simulated at multi-trophic levels. We expect that phylogenetic distance and functional diversity will favour species complementarity. Several functions will be examined, to test how biodiversity can maintain ecosystems ‘multi-functionality’. Biodiversity is also expected to buffer the impacts of climate change contributing to system stability. Then, results from mesocosms will be validated along environmental gradients in streams. This will allow us to test which biodiversity measure (taxonomic diversity, functional diversity or phylogenetic divergence) best explains ecosystem functions taking into account environmental variability.

To reach a broader understanding of climate change impacts, we will conduct a meta-analysis with data from literature and from STREAMECO. At the end, we will develop a predictive model to reveal how environmental variables related to climate change influence biodiversity, ecosystem functions and services that can support decision making in environmental management.