@article {105151, title = {Life at the borderline: Responses of Ganges river dolphins to dry-season flow regulation of river and canal habitats by the Farakka barrage}, journal = {AQUATIC CONSERVATION-MARINE AND FRESHWATER ECOSYSTEMS }, year = {2021}, month = {12/2021}, abstract = {

Modification of river flows by dams and barrages has fragmented riverine habitats and threatened the survival of Indian subcontinental river dolphins. In this study, habitat use by endangered Ganges river dolphins in response to dry-season operations (December-March) of the Farakka barrage on the Ganga River, located about 20 km upstream of the India-Bangladesh border, was assessed. Ten surveys were conducted in: (i) the Ganga River below the barrage, where rapid changes in water levels were expected owing to barrage operations; (ii) the Farakka feeder canal with stable water levels; and (iii) the Hooghly River downstream of the canal. Dolphin distribution, water depth, fishing boat count and temperature were recorded in all surveys and the data were analysed in a dynamic occupancy modelling framework. Temporal trends in river discharge, primary productivity and fish availability were also estimated to explain river dolphin responses. Occupancy and colonization by dolphins increased in all stretches by spring/March, correlated with rising water temperature and increased fishing intensity, which was related to upstream migration of hilsa fish. In the Ganga River, dolphin occupancy in deep river pools remained stable, but resulted in increased overlap with fisheries as river flow declined. The feeder canal, with stable flows, witnessed increased colonization by dolphins, but also greater risk of bycatch in fishing nets. The canal that appeared as a hydrological refuge thus became an {\textquoteright}ecological trap{\textquoteright}. The findings highlight the need for integration of flow maintenance and fishery regulations in the monitoring and management of canals as effective refuges for riverine species. We advocate the inclusion of ecological flow criteria and fishery regulations to reduce dolphin bycatch mortality, in the context of establishing river dolphin conservation plans and transboundary water-sharing guidelines. The revision of the India-Bangladesh water-sharing treaty in 2026 could incorporate the above considerations.

}, doi = {10.1002/aqc.3763}, author = {Samad, Imran and Kelkar, Nachiket and Krishnaswamy, Jagdish} } @article {67819, title = {Interacting effects of vessel noise and shallow river depth elevate metabolic stress in Ganges river dolphins.}, journal = {Sci Rep}, volume = {9}, year = {2019}, month = {2019 Oct 28}, pages = {15426}, abstract = {

In riverine {\textquoteright}soundscapes{\textquoteright}, complex interactions between sound, substrate type, and depth create difficulties in assessing impacts of anthropogenic noise pollution on freshwater fauna. Underwater noise from vessels can negatively affect endangered Ganges river dolphins (Platanista gangetica), which are {\textquoteright}almost blind{\textquoteright} and rely entirely on high-frequency echolocation clicks to sense their environment. We conducted field-based acoustic recordings and modelling to assess acoustic responses of Platanista to underwater noise exposure from vessels in the Ganga River (India), which is now being transformed into a major waterway. Dolphins showed enhanced activity during acute noise exposure and suppressed activity during chronic exposure. Increase in ambient noise levels altered dolphin acoustic responses, strongly masked echolocation clicks, and more than doubled metabolic stress. Noise impacts were further aggravated during dry-season river depth reduction. Maintaining ecological flows, downscaling of vessel traffic, and propeller modifications to reduce cavitation noise, could help mitigate noise impacts on Ganges river dolphins.

}, issn = {2045-2322}, doi = {10.1038/s41598-019-51664-1}, author = {Dey, Mayukh and Krishnaswamy, Jagdish and Morisaka, Tadamichi and Kelkar, Nachiket} } @article {45435, title = {Fish community responses to stream flow alterations and habitat modifications by small hydropower projects in the Western Ghats biodiversity hotspot, India}, journal = {Aquatic Conservation: Marine and Freshwater Ecosystems}, volume = {28}, year = {2018}, month = {08/2018}, pages = {9792-993}, abstract = {
  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. The SHPs were found to have severe impacts on stream geometry, water chemistry, and aquatic biota, especially in the dry season.
  6. 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.
}, doi = {10.1002/aqc.2904}, author = {Jumani, Suman and Rao, Shishir and Kelkar, Nachiket} } @article {3568, title = {First record of a bat from the Lakshadweep archipelago, southwestern India}, journal = {Mammalia}, volume = {80}, year = {2016}, month = {March 2016}, pages = {223-225}, abstract = {

he first record of a bat species from the Lakshadweep archipelago (India) has been identified as Tadarida aegyptiaca (Chiroptera: Molossidae). It appears unlikely that any bat colony may have been resident on the islands. Stranding during migration, high aerial foraging, or disorientation by wind farms on the west coast of mainland India, are factors that need to be further explored to explain this occurrence

}, doi = {10.1515/mammalia-2014-0119,}, url = {http://www.degruyter.com/view/j/mamm.ahead-of-print/mammalia-2014-0119/mammalia-2014-0119.xml}, author = {Deshpande, Kadambari. and Gangal, Mayuresh and Kelkar, Nachiket} }