Can Recent Global Changes Explain the Dramatic Range Contraction of an Endangered Semi-Aquatic Mammal Species in the French Pyrenees?

Abstract

Species distribution models (SDMs) are the main tool to predict global change impacts on species ranges. Climate change alone is frequently considered, but in freshwater ecosystems, hydrology is a key driver of the ecology of aquatic species. At large scale, hydrology is however rarely accounted for, owing to the lack of detailed stream flow data. In this study, we developed an integrated modelling approach to simulate stream flow using the hydrological Soil and Water Assessment Tool (SWAT). Simulated stream flow was subsequently included as an input variable in SDMs along with topographic, hydrographic, climatic and land-cover descriptors. SDMs were applied to two temporally-distinct surveys of the distribution of the endangered Pyrenean desman (Galemys pyrenaicus) in the French Pyrenees: a historical one conducted from 1985 to 1992 and a current one carried out between 2011 and 2013. The model calibrated on historical data was also forecasted onto the current period to assess its ability to describe the distributional change of the Pyrenean desman that has been modelled in the recent years. First, we found that hydrological and climatic variables were the ones influencing the most the distribution of this species for both periods, emphasizing the importance of taking into account hydrology when SDMs are applied to aquatic species. Secondly, our results highlighted a strong range contraction of the Pyrenean desman in the French Pyrenees over the last 25 years. Given that this range contraction was under-estimated when the historical model was forecasted onto current conditions, this finding suggests that other drivers may be interacting with climate, hydrology and land-use changes. Our results imply major concerns for the conservation of this endemic semi-aquatic mammal since changes in climate and hydrology are expected to become more intense in the future.

Comparison of diet and prey selectivity of the Pyrenean desman and the Eurasian water shrew using next-generation sequencing methods

“…1). This area exhibits relatively high occurrence of G. pyrenaicus Charbonnel et al, 2015Charbonnel et al, , 2016, and the presence of N. fodiens was recently reported (Charbonnel et al, 2015). The mean elevation of the 65 sampling sites is 757.9 ± 259.3 m and varies between 375.2 m and 1755.6 m. Mean monthly stream flow equals to 1.1 ± 2.0 m 3 /s with a maximum of 13.2 m 3 /s .…”

“…The alarming decline of G. pyrenaicus populations over the recent decades across its whole range Gisbert and García-Perea, 2014) has encouraged local, national and European conservation initiatives (e.g., in France: Life+ Desman, 2013;Némoz et al, 2011). Yet, in spite of an increasing number of studies focusing on this species (e.g., Aymerich and Gosàlbez, 2015;Biffi et al, 2016;Charbonnel et al, 2016;Escoda et al, 2017), the respective influence of prey, competitors and predators on its survival and distribution still remains to be explored.…”

Need for speed: Preference for fast‐flowing water by the endangered semi‐aquatic Pyrenean desman (Galemys pyrenaicus) in two contrasting streams

“…In particular, local extinctions have been attributed to artificial barriers to dispersal, such as dams or highly altered reaches in a dendritic network where biogeographic barriers already abound (Morueta‐Holme et al, ). Comparing the historical with the present distributions of the species in France, Charbonnel et al () concluded that the range contraction observed is larger than expected from the decrease in habitat suitability caused by climate, and hydrological and land‐use changes. They speculated that the decline may be caused by additional factors such as habitat fragmentation, pollution, changes in prey availability, or invasive species (e.g.…”

“…Its distribution area has been severely reduced during recent decades, and it is currently listed as a vulnerable species in the Red List categories by the International Union for Conservation of Nature (IUCN) (Fernandes, Herrero, Aulagnier, & Amori, ). The reasons behind this decline are not well known, but seem to be mainly linked to anthropogenic factors such as water pollution, habitat degradation (canalization, river‐bank degradation, flow modification), and stream fragmentation (Charbonnel et al, ; Queiroz, Bertrand, & Gennady, ; Williams‐Tripp et al, ). It must be noted that the population decline occurs even in regions such as the Basque Country (Ihobe, ; Rubio, ; Ura, ), where pollution has abated as a consequence of improved sanitation and water‐treatment schemes.…”

“…Most of the studies have coarse spatial resolutions, because environmental data have not been calculated in the field. In addition, almost all habitat studies for the Pyrenean desman have been based on stool detections as signs of presence (Barbosa, Real, & Vargas, ; Charbonnel et al, , ; Morueta‐Holme et al, ; Williams‐Tripp et al, ). None of these studies have been made using telemetry data, which could give new relevant information for individual identification and the tracking of displacements.…”