Assessing the recovery of fish assemblages downstream of hydrological barriers in India's Western Ghats

Atkore, Vidyadhar; Kelkar, Nachiket; Krishnaswamy, Jagdish

doi:10.1002/rra.3163

Cited by 6 publications

(10 citation statements)

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“…This is especially crucial given that India's Ministry of New and Renewable Energy had, up until 2012, commissioned 1266 SHPs, and identified 6474 sites for further SHP development (MNRE, 2015). Undammed tributaries within regulated river basins must be identified for conservation, as a recent study has shown that the presence of some undammed tributaries is critical in facilitating the recovery of endemic fish species downstream of hydrological barriers in the Western Ghats (Atkore et al, ). In addition, experimental approaches to test the effectiveness of mitigation measures should be encouraged, such as the translocation of fish from dewatered regions and reservoirs to downstream regions during sediment flushing operations.…”

Section: Discussionmentioning

confidence: 99%

“…As a result of reduced stream flows, water temperatures would be higher and dissolved oxygen levels would be lower in the dammed DW location category (Anderson, Pringle, & Rojas, ). Reduced surface inflows in the dammed DW location could result in an increased relative groundwater contribution to base flows (Atkore, Kelkar, & Krishnaswamy, ). Hence, these locations would have higher pH and electrical conductivity compared with the corresponding control site. Fish community composition would vary between dammed and undammed streams.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fish community responses to stream flow alterations and habitat modifications by small hydropower projects in the Western Ghats biodiversity hotspot, India

Jumani¹,

Rao

Kelkar

et al. 2018

Aquatic Conservation

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Small hydropower projects (SHPs) are promoted as environmentally benign alternatives to larger dams; however, the impacts of SHPs have been poorly studied, especially in tropical developing countries, where their growth is being encouraged. This study assessed the impacts of two SHPs on freshwater fish communities in the Western Ghats biodiversity hotspot of India. Two dammed and one undammed tributary of the Netravathi River, having similar stream order, elevation, and surrounding land‐use types, were identified as test and control sites respectively. Stream geometry, water chemistry, and fish assemblages were compared across upstream, dewatered, and downstream location categories within and across the three streams. Flow alterations induced by SHPs affected the dewatered river stretches most severely. Stream wetted width and depths diminished drastically in dammed dewatered segments, and consequently this region was characterized by elevated water temperature and reduced dissolved oxygen. Fish species composition varied significantly between dammed and undammed sites, across the upstream, dewatered, and downstream location categories. Dammed segments had lower fish species richness, diversity, and endemicity, and were dominated by eurytopic species (adapted to lentic conditions), unlike the control site, which was dominated by rheophilic species (adapted to flowing waters). Regression analyses indicated that fish species richness in dammed streams increased with distance from the dam in the upstream direction. The SHPs were found to have severe impacts on stream geometry, water chemistry, and aquatic biota, especially in the dry season. Given the ambitious targets of planned SHP growth, most of which are within ecologically fragile regions, changes in SHP operations and policies are proposed to enable the conservation of river fish diversity. These include mandatory environmental impact assessments, conserving undammed headwater streams in regulated basins, maintaining adequate environmental flows, and implementing other mitigation measures.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fish community responses to stream flow alterations and habitat modifications by small hydropower projects in the Western Ghats biodiversity hotspot, India

Jumani¹,

Rao

Kelkar

et al. 2018

Aquatic Conservation

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“…Other local disturbances to stream biota are from intensive instream fishing and sand‐boulder mining (Atkore et al. ).…”

Section: Methodsmentioning

confidence: 99%

Multiscale Investigation of Water Chemistry Effects on Fish Guild Species Richness in Regulated and Nonregulated Rivers of India's Western Ghats: Implications for Restoration

et al. 2020

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Tropical rivers across the world are experiencing rapid degradation and loss of fish species due to flow regulation, pollution, and other anthropogenic pressures. Knowledge of how flow alterations at different scales affect tropical fish diversity remains limited, especially in terms of how resulting changes in water chemistry affect fish communities. We investigated fish guild composition and responses of guild richness to water chemistry in 120 river segments with and without local-scale water removals and pollution. This included two regulated subbasins (with flow regulation by barrages and large-scale water diversions) and two nonregulated subbasins (flows not regulated by these barriers) in India's Western Ghats. Using multivariate ordination and regression models, we identified covariates related to water chemistry and environmental characteristics that explained differences in fish species composition and species richness of three water column position-based fish guilds in the study area. At the subbasin scale, effects of water chemistry were stronger for individual river segments. At the segment scale, no differences in water chemistry were found between segments with and without water removals or pollution in both regulated and nonregulated subbasins. Guild-

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“…We classified the fish based on their flow preference guild (FPG) as either rheophilic species, which are adapted to live specifically in lotic (flowing water) systems, or eurytopic species, which can live in both lotic and lentic (lakes and ponds) systems (Atkore, Kelkar, Badiger, Shanker, & Krishnaswamy, 2020; Atkore, Kelkar, & Krishnaswamy, 2017;Chakrabarty & Homechaudhuri, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…In the dewatered segment, e-flow implementation may be relatively easier since this segment is immediately downstream of the reservoir. In addition, SHP design and placement of can prioritize locations such that dewatered segments can be naturally augmented by other unregulated tributaries to aid the recovery of fish assemblages (Atkore et al, 2017). However, in the downstream segment, implementing e-flows can be challenging since the pulsed discharge from the powerhouse is likely to compromise the effectiveness of e-flows.…”

Section: Management Implicationsmentioning

confidence: 99%

Linking flow alteration with fish assemblage structure in a river regulated by a small hydropower project in the Western Ghats of Karnataka, India

Rao

Krishnaswamy

Bhalla³

2021

River Research & Apps

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Small hydropower projects (SHPs) are promoted as low-impact alternatives for large hydropower. SHPs are generally commissioned on small-to medium-sized mountainous rivers, often in biodiverse regions, with backing in the form of subsidies, facultative policies and exemption from impact assessments as they are considered 'green'.However, the ecological impacts of SHPs are understudied especially in highly seasonal tropical streams of Western Ghats of India, a global biodiversity hotspot and a distinct freshwater fish eco-region. We compared SHP-affected segments of a dammed and an undammed river in the Western Ghats of Karnataka, to assess how altered flow regime affects seasonal variability in habitat and water quality, and influences fish assemblage structure. We found that flow alteration by the SHP varied between different segments of the dammed river and with season. Furthermore, the nature of flow alteration influenced habitat variability, water quality and fish assemblage response in the dammed river. We observed that the dewatered segment of the dammed river experienced a lotic to lentic shift in habitat and water quality, which favoured fish species with eurytopic affinities. Fluctuating flows in the downstream segment subdued natural variability in flow regime and created novel habitats and water-quality conditions, affecting fish assemblages. The upstream segment of the dammed river retained natural variability in habitat and water quality, but did not mimic the undammed river in terms of fish composition. We also observed potential constraints on recruitment for migratory species of fish in the dammed river. Based on our results, we suggest how the placement of dewatered segment, and timing the closure of SHP operation in dry season based on ecological thresholds are potential solutions to mitigate the impacts of the SHPs. Furthermore, we recommend effective impact assessments, and adaptive management with active interventions to maintain genetic and ecological connectivity, as key to enhance the sustainability of the SHPs.

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Assessing the recovery of fish assemblages downstream of hydrological barriers in India's Western Ghats

Cited by 6 publications

References 58 publications

Fish community responses to stream flow alterations and habitat modifications by small hydropower projects in the Western Ghats biodiversity hotspot, India

Fish community responses to stream flow alterations and habitat modifications by small hydropower projects in the Western Ghats biodiversity hotspot, India

Multiscale Investigation of Water Chemistry Effects on Fish Guild Species Richness in Regulated and Nonregulated Rivers of India's Western Ghats: Implications for Restoration

Linking flow alteration with fish assemblage structure in a river regulated by a small hydropower project in the Western Ghats of Karnataka, India

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