Research Article: Spatiotemporal variability in water quality, ichthyofaunal diversity, and its conservation in the rivers of Nepal: A mini review

Nepal has a diverse geography, ranging from an altitude of ۶۰ m to the world's highest peaks at ۸۸۴۹ m. Fish diversity has been observed to extend up to an elevation of ۳۶۰۰ m. With its intricate topography, fluctuating climatic conditions, and abundant water resources, the region exclusively comprises freshwater habitats spanning ۷۴۵,۰۰۰ ha. These habitats include rivers, lakes, ponds, marshes, reservoirs, and irrigated rice fields. There are roughly ۶,۰۰۰ rivers and creeks in the country (۱۹۴,۴۷۱ km² drainage area). Four major river systems, namely Koshi, Gandaki, Karnali, and Mahakali, originate from the upper Himalayas at an altitude greater than ۵۰۰۰ m above sea level and drain about ۷۵% of the country. Freshwater fishes are often overlooked in biodiversity conservation efforts, leading to a significant decrease in fish diversity, particularly in densely populated urban areas and wetlands in the southern plains of Nepal. The decrease in fish diversity is likely linked to inadequate prioritization, funding, and human resources allocated to fish conservation. According to the literature and FishBase database records, the freshwater river system in Nepal contains a total of ۲۵۵ fish species from ۱۲ orders, ۴۱ families, and ۱۲۴ genera. This includes ۱۵ fish species that are unique to Nepal and ۱۵ that are not native to the region. Additionally, ۳۴ fish species in this system are considered threatened and have been listed under the IUCN Red List. These fish have pronounced vertical dispersion throughout the country and horizontal distribution within the area and continent, displaying diverse adaptations. This research specifically examines the fluctuations in water quality and the range of fish species, together with their conservation status in the rivers of Nepal.

کلیدواژه ها:

Spatiotemporal ، Variability ، Fish diversity ، Lakes ، Nepal ، River ، Water Resources