Freshwater conservation in a fragmented world: Dealing with barriers in a systematic planning framework

• Published in: Aquatic Conservation: Marine and Freshwater Ecosystems
• Main Authors: Hermoso, Virgilio, Filipe, Ana Filipa, Segurado, Pedro, Beja, Pedro
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2017
• Subjects: European eel
• Online Access: http://dx.doi.org/10.1002/aqc.2826; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Faqc.2826; https://onlinelibrary.wiley.com/doi/pdf/10.1002/aqc.2826

Abstract Disruption of longitudinal connectivity poses one of the most important threats to the persistence of freshwater biodiversity worldwide. Longitudinal connectivity plays a key role by facilitating ecological processes, such as migrations or energy transfer along river networks. For this reason, effective conservation of freshwater biodiversity is highly dependent on a capacity to maintain all processes associated with connectivity. Freshwater protected areas are commonly affected by disruptions of connectivity due to human activities and recent approaches to addressing connectivity when identifying priority areas have overlooked the limitations that human perturbations pose to connectivity. Here, a novel approach is presented to address this issue by accounting for the spatial distribution of barriers using Marxan, a tool commonly applied in conservation planning. This approach was first tested on a simulated example and then applied to the identification of priority areas for the conservation of freshwater vertebrates in the Iberian Peninsula (Spain and Portugal). When using this new approach, the number of disrupted connections within priority areas can be significantly reduced at no additional cost in terms of area needed, which would help maintain connectivity among populations of species with low–medium migratory needs. Given the widespread occurrence of barriers in the study region, the improvement in connectivity within priority areas also resulted in the selection of river reaches closer to the headwaters and the river mouth. Focusing on both extremes of the longitudinal gradient might compromise the effectiveness of conservation efforts for long‐distance migratory species, such as the European eel. This inevitably means that additional management measures, such as barrier removal or construction of fish passages, would be necessary to ensure that these species are able to complete their life cycles. The method demonstrated here could be applied to other regions where connectivity is compromised.