Combining expert-based and computational approaches to design protected river networks under climate change

• Published in: Diversity & distributions Vol. 27; no. 12; pp. 2428 - 2440
• Main Authors: Floury, Mathieu, Pollock, Laura J., Buisson, Laëtitia, Thuiller, Wilfried, Chandesris, André, Souchon, Yves
• Format: Journal Article
• Language: English
• Published: Oxford Wiley 01-12-2021; John Wiley & Sons, Inc
• Subjects: Aquatic ecosystems; Biodiversity; Biodiversity and Ecology; Brown trout; Climate change; climate change uncertainty; Computer applications; Conservation; conservation planning; Contraction; Creeks & streams; Design; directed longitudinal connectivity; Ecosystems; Environmental Sciences; Fish; Geographical distribution; Precipitation; Protected areas; protected river networks; Refugia; Regional planning; RESEARCH ARTICLE; River basins; River networks; riverine systems; Rivers; Salmo trutta; Seasonal variations; Spatial dependencies; spatial stream network model; species distribution model; species range shifts; Strategic management; Trout; Uncertainty; France; directed longitudinal connectivity; spatial stream network model; Salmo trutta; Brown trout; climate change uncertainty; conservation planning; protected river networks; riverine systems; species distribution model; species range shifts
• ISSN: 1366-9516; 1472-4642
• DOI: 10.1111/ddi.13411

Aim
Estimate the current and future distribution of brown trout and identify priority areas for conservation of the species.
Location
Rhône River basin and Mediterranean streams.
Methods
We first developed a spatially explicit species distribution model to estimate the current and future distribution of brown trout for three time horizons (2030, 2055 and 2080) and two climate change scenarios (RCP 4.5 and RCP 8.5). We then performed a prioritization analysis to identify priority areas for brown trout conservation, accounting for: (a) spatial dependencies along the riverine system, (b) several sources of uncertainty arising from climate‐related forecasts and (c) different protected area scenarios by comparing hypothetical, optimal protected networks to an actual protected network designed by regional fish experts.
Results
Future projections of brown trout densities exhibited a general trend towards a gradual range contraction, with a significant risk of extirpation across mountainous regions of low to mid‐elevation. Overall, the projected current and future distributions were well‐covered by the existing protected network. In addition, up to 70% of the river reaches included in this expert‐based protection network were also priorities in the optimal priority set (e.g. the best set of areas to maximize biodiversity protection). Finally, a large proportion of these reaches were invariably identified regardless of climate change scenarios and uncertainties or spatial dependencies.
Main conclusions
Our analytical approach highlighted priority areas for brown trout conservation which were robust to a set of climate and connectivity assumptions. This core priority network could be further refined by taking into account key fine‐scale processes like thermal refugia. Therefore, we advocate for combining computational and expert‐based approaches in conservation planning of riverine ecosystems to achieve a relevant consensus between regional‐scale management and fine‐grain ecological knowledge.