Promoting connectivity between priority freshwater sites for conservation in intermittent hydrological systems

Abstract

Systematic conservation planning in freshwater ecosystems faces multiple challenges because of the dynamic nature of rivers and their multiple dimensions of connectivity. In intermittent hydrological systems connectivity is functional when water is available, allowing the exchange of aquatic individuals between isolated freshwater ecosystems. Integrating these isolated systems in their hydrological context is essential when identifying priority areas for conservation, in order to try to minimize the propagation of threats into target water bodies (management units) from the surrounding landscape. Here, the use of a systematic planning approach is demonstrated to identify a set of priority management units to preserve freshwater biodiversity in an arid system of fragmented water bodies immersed in a landscape subject to a range of impacts. Twenty‐six water‐dependent taxa from 59 mountain rock pools (gueltas) of three southern Mauritanian mountains were used as a case study. A conservation planning tool (marxan) was used to find priority conservation areas to integrate intermittent hydrological systems in their hydrological context, promote connectivity, and minimize the downstream propagation of threats. Three types of connectivity were analysed: (i) no connectivity, (ii) connectivity between gueltas, and (iii) connectivity between gueltas and sub‐catchments. Considering different types of longitudinal connectivity affects the number and spatial allocation of the priority gueltas selected, and the conservation status of the gueltas and their upstream areas. Incorporating connections between gueltas and upstream locations in the modelling resulted in the selection of gueltas in areas with a low human footprint and in the increased connectivity of the solutions. The results obtained revealed important locations for local biodiversity conservation, and the method presented can be used when assessing the propagation of potential waterborne threats into isolated management units. The framework developed allows connectivity to be addressed in conservation planning. It can be replicated in regions with similar isolated habitats that connect through intermittent hydrological systems and can also be applied to lateral and vertical hydrological connectivity.

Integrating spatiotemporal hydrological connectivity into conservation planning to protect temporary rivers

“…Hydrological connectivity also played a role in the selection of sites by MSF, with spatially isolated sites being often selected to represent rare taxa. Overall, our results suggest that conservation plans should adequately capture the natural hydrological variability of drying river networks, because the networks can also have temporary reaches with high conservation value (Hamdhani et al, 2020; Hermoso et al, 2013; Naia et al, 2021; Vander Vorste et al, 2020).…”

The role of connectivity in conservation planning for species with obligatory interactions: Prospects for future climate scenarios

“…From a conservation perspective, the long‐term persistence of these species could be at high risk: even if we manage to cover their last strongholds, they will be less connected and therefore subject to the effects of declining genetic diversity and stochastic natural events that may increase the extinction risk. Accordingly, it is widely recognized that habitat connectivity should be taken into account when selecting priority areas, both in freshwaters (Bush et al., 2014; Hermoso et al., 2018; Hermoso, Clavero, & Filipe, 2021; Hermoso & Filipe, 2021; Hermoso, Vasconcelos, et al., 2021; Lin et al., 2018; Naia et al., 2021), and in other realms (Alagador et al., 2016; Magris et al., 2014, 2016; Triviño et al., 2018).…”

Diversity, distribution and conservation of land mammals in Mauritania, North-West Africa

“…These high-standing and dense forests result from the seasonal flooding of the river valley and are important nesting sites for birds and breeding habitats for amphibians [ 27 , 32 ]. They would have the potential to be used as stepping-stone habitats along the main course of the Senegal River by aquatic and semi-aquatic mammals, as well as forest dwelling species; and 2) the formal protection of mountain rock-pools and the associated drainage systems that ensure seasonal connectivity [ 98 ], and gene flow between isolated populations of water-dependent taxa, as demonstrated in crocodiles [ 99 ]. Water availability in the mountain rock-pools has also been identified as critical environmental factor associated with the occurrence of many rock-specialist mammals and other fauna [ 33 , 51 — 53 , 69 ].…”