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

Abstract

1. 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.2. 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).3. 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. 4. 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. 5. The method demonstrated here could be applied to other regions where connectivity is compromised.

Protected areas and freshwater biodiversity: a novel systematic review distils eight lessons for effective conservation

“…We distilled the evidence into eight lessons for improving protected area assessment, design, and management to enhance freshwater conservation effectiveness. Our lessons build on many previous works (e.g., Adams et al., ; Fiedler & Karieva, ; Hermoso et al., , ; Strayer & Dudgeon ) and strengthen their essential messages by providing empirical evidence from the systematic literature search.…”

“…We recommend monitoring a wider range of faunal groups as well as plants and algae. Further work is also necessary to define new metrics for measuring freshwater protected area effectiveness that capture spatial and temporal variations in ecological processes and responses to common stressors, as well as typical metrics of change in biodiversity or the abundance of particular taxa (Hermoso et al., , ). Greater recognition of variability and time lags in population and community responses could help us understand why some protected area assessments reveal positive biodiversity outcomes and others do not (Adams et al., ; Geist, ).…”

Characterizing surrogacy performance in the systematic conservation planning of riverine networks

“…molluscs, crayfishes). Therefore, we emphasize that not only total area but also the spatial configuration of PUs is an important landscape‐level variable, which should be better considered when selecting surrogate taxa in conservation planning (Erős et al, ; Hermoso, Filipe, Segurado, & Beja, ). Overall, of the three groups examined, FI appears to be ideal indicator taxa for connectivity conservation.…”

Toward process‐based conservation prioritizations for freshwater ecosystems

“…This is especially pertinent for migration disruptions by dams, weirs, or roads that can significantly compromise the conservation of long‐distance migratory species. Hermoso, Filipe, Segurado, and Beja () considered the potential disruptions to longitudinal connectivity by large dams (>100 hm 3 ) when planning for freshwater biodiversity protected areas in the Iberian Peninsula. The goal of this study was to find river reaches not disrupted by dams (i.e.…”