Aquatic ecosystems are currently facing an unprecedented biodiversity crisis linked to human activities and with even worse future scenarios. Among many potential drivers, habitat fragmentation still remains as one of the least understood due to its complexity. Furthermore, its interaction with other local stressors such as salinity remains as a major knowledge gap that hinders long-term conservation.
Ponds host high local and regional biodiversity and contribute to important ecosystem functions and services. At the same time, the networks of these priority habitats are disappearing worldwide (50-90% of habitat already lost). However, the impacts of fragmentation and salinity increase on their biodiversity are yet to be unfolded.
Meta-Heroes aims to shed light on the role of network connectivity in safeguarding biodiversity against environmental stressors by analysing pond communities in a multidisciplinary approach combining experimental work (WP1 mesocosms), empirical data (WP2 long-term dataset) and a simulation framework to asses future scenarios (WP3 graph-based models).
WP1 uses a large-scale setup with experimental ponds (mesocosms) and their plankton communities. We have reproduced natural habitats with different connectivity (Central vs Isolated) and different salinity impacts (Freshwater vs Saline) to track their response along a two months experiment.
WP2 benefits from a unique long-term dataset on zooplankton covering more than 60 years. Along this period the landscape suffered marked connectivity and habitat loss with the concomitant impoverishment of aquatic communities. We analysed the major drivers of this loss (i.e. habitat size, wind dispersal, conductivity increase, loss of connectivity) using digital simulations that allowed us to identify the specific role that each driver played.
WP3 models biodiversity changes derived from large-scale habitat loss and/or network fragmentation scenarios. Using continental-scale water surface satellite data, we simulate the expected diversity loss derived from the loss of habitat structure.
The combination of these three approaches together with my supervisor, host institute and international collaborators will result in robust novel results, informative for both basic ecology and conservation.
Along the project time, I fully attain the major goals of MetaHeroes. This allowed me to answer the main project objective, which is summarised in the following statements:
• Connectivity plays a major role in driving diversity, fostering higher abundance and more homogeneous composition of communities.
• Connectivity alone cannot counterbalance high-intensity (i.e. high salinity) or large-scale (i.e. habitat size decrease plus habitat loss plus conductivity rise) stressors as they also drive diversity and concomitantly influence
• Greater connectivity diminishes diversity decay against habitat loss at regional scales, being regions with greater heterogeneity (high and low connected areas) those where diversity is less impacted due to habitat loss and fragmentation.
In conclusion, connectivity plays a crucial role in defining biodiversity trends, yet this role needs to be framed as an interactive factor that is in turn modulated by other local or regional stressors. Overall, connectivity must be incorporated into existing conservation practices as it may determine the resistance and resilience to habitat degradation, yet considering connectivity alone will only allow us to palliate the effect of regional-scale degradation, which will end-up by diminishing diversity.
Overall, Meta-Heroes has been a key milestone to expand my professional network and scientific toolsets enhancing the development of my career as an independent researcher.
