Understanding the influence of check dam and season on habitat use to develop habitat suitability criteria for overwintering tadpoles of Nanorana spp.

Abstract

Understanding habitat availability and use patterns are essential in developing comprehensive conservation strategies for focal species. Studies on amphibian larval habitat use are limited, especially from modified habitats. We investigated the habitat availability and use patterns of overwintering tadpoles of the Nanorana frog in an anthropogenically modified stream in the western Himalaya. Habitat was assessed in terms of depth, velocity, substrate type, and instream cover. We quantified the microhabitat preference of the tadpoles to develop habitat suitability criteria (HSC) curves, the biological component of habitat simulation tools used in instream flow management. We analyzed the data covering winter and post‐winter seasons using cumulative link mixed models to understand the influence of check dams and seasons on the hydraulic properties of microhabitats used by the tadpoles. We confirm the influence of check dam and season on velocity and the influence of season on depth used by the tadpoles. Based on this, we generated HSCs for tadpoles occurring in natural and modified pools during both seasons. We recommend intermediate water depths (30–60 cm) during the low flow season to sustain the tadpole population in the study stream and other required habitat features. The study underlines the importance of spatial and temporal variation in the habitat suitability for Nanorana tadpoles. These HSCs can be used in hydrological models for estimating the minimum ecological flow for overwintering tadpoles in the study area. A large‐scale study based on the recommendations can lead to a better conservation plan in light of altered streamflow in the western Himalaya region.