Small increases in stream drying can dramatically reduce ecosystem connectivity

Abstract

Habitat fragmentation drives biodiversity loss in rivers around the world. Although the effects of anthropogenic barriers on river connectivity are well known, there has been little research on the ways in which stream drying may alter connections among habitats and resources. Given that stream drying is increasing in many regions, there is a pressing need to understand the effects of drying on habitat fragmentation. Here, we quantify spatiotemporal drying patterns under current and future climate scenarios in the Upper Blue River Basin, Oklahoma. We used a hydrologic model to simulate daily streamflow for nine climate scenarios. For each scenario, we calculated metrics of streamflow temporal continuity (dry days, dry periods, and dry period duration) and spatial connectivity (wetted length, number of dry stream fragments, length of dry stream fragments, and dendritic connectivity index) from simulated daily streamflow. We found that stream drying is likely to increase in all future climate scenarios and that increases in stream drying reduce connectivity. However, the effects of stream drying on connectivity were highly nonlinear. Specifically, we observed a threshold around which a small increase in stream drying led to a rapid drop in connectivity. We also found that the greatest increases in stream drying were not associated with the highest emission scenarios, underscoring the complex linkages among climate, water availability, and connectivity. Given that connectivity is essential to ecosystem structure and function, we discuss water management strategies informed by impacts of stream drying.

Effects of episodic stream dewatering on brook trout spatial population structure

“…Prior research in dryland ecosystems indicates increased extirpation risks for stream fishes from dewatering and habitat fragmentation (Falke et al., 2012; Jaeger et al., 2014; Vander Vorste et al., 2020), and our study extends this inference to a temperate biome characterised by relatively high precipitation. Moreover, given anticipated increases in dewatering intensity and frequency due to global climate change (Datry et al., 2014; Jaeger et al., 2014; Malish et al., 2023), the ecological responses to dewatering we observed may have utility for predicting future conditions in temperate stream ecosystems elsewhere.…”

Hydro‐modeling the ecosystem impact of wastewater reuse under climate change: A case study in upper Red River basin, Oklahoma

“…Reduced water availability stands as a primary factor causing stress to freshwater ecosystems worldwide (Vörösmarty et al., 2010). The Great Plains region has seen increasing evidence of this issue (Malish et al., 2023; Perkin et al., 2015). This study demonstrates the challenge of watershed management—how to acquire additional water availability while preserving stream flows for aquatic ecosystems.…”

Increased drying threatens alpine pond biodiversity more than temperature increase in a changing climate

“…Such changes have already lead to mass mortality events with occasional species disappearance (e.g., amphibians, plants), and a shift in dominance to species that are tolerant to drier conditions (Carlson et al, 2020;He et al, 2016;Sandvik & Odland, 2014). Another consequence of drying is loss of habitat connectivity, as suitable patches become increasingly isolated (Malish et al, 2023). Decreased connectivity among patch habitats reduces species migration success (when possible) as it lengthens travel distances, and recolonization of previously occupied patches becomes dependent on rewetting frequencies (Bogan et al, 2015).…”