Degrading waterscapes and decaying diversities: Assessing habitat loss and fragmentation consequences on simulated diversity patterns across European freshwater ecoregions. Running title: Simulating diversity response to waterscape degradation

Aim Aquatic landscapes face severe threats from human activities propelling their deterioration. Waterscape degradation represents a main driver of the current diversity crisis but its large-scale consequences for ecoregions are difficult to quantify. Here we provide a framework to assess the potential impact of waterscape degradation by simulating diversity decay of European ecoregions. Through this approach, we aim to identify regional sensitivity patterns to degradation and its large-scale determinants.

Location Europe Time period From 1984 until 2019

Major taxa studied Freshwater organisms with aerial or terrestrial dispersal capacity. 

Methods We reconstructed the European waterscape based on satellite data and explored its connection with diversity using metacommunity models. Subsequently, we generated a gradient of dispersal abilities and a gradient of waterscape degradation by systematically removing a percentage of habitat and estimating gamma diversity for each level. We synthesized the diversity decay patterns in two parameters: the proportional decay rate and the collapsing rate, which respectively inform about the speed of diversity loss and its acceleration as waterscape degradation progresses.

Results We observed major differences in the potential response to waterscape degradation across regions. Connectivity and water cover emerged as primary descriptors of diversity decay, being the ecoregions with a more heterogeneous waterscape structure the most resistance to degradation.

Main conclusions Our study provides a first order approximation to a needed information: the large-scale consequences of waterscape degradation for biodiversity. This contribution focuses on the role that waterscape configuration plays in sustaining diversity and how it may differently decay with global change impacts. Furthermore, the theoretical perspective developed herein paves the way to include further mechanisms and/or spatial changes at different regional scales. Our approach can improve conservation by considering large-scale features. Thus, the present results enhance our understanding of the consequences of waterscape structural degradation to freshwater diversity, but they also set the background for breaking current conservation halts using novel perspectives. 

Keywords: Diversity decay; landscape fragmentation; habitat loss; landscape degradation; landscape conservation; aquatic habitats