The rivers and streams of Himalayan region are most vulnerable to climate change and are likely to affect all freshwater ecosystems and their fauna. Benthic macroinvertebrates are sensitive to changes in temperature, precipitation, and the associated flow regimes, which make them particularly responsive to the effects of climate change.
There are three objectives of the study- 1) to assess the water quality of fifteen streams at different altitude (700 m – 3700 m) from Manaslu Conservation Areas (MCA) and Annapurna Conservation Areas (ACA) using benthic macroinvertebrates (BMI) as biological indicators with the help of biotic indices such as NEPBIOS, BMWP/ASPT, and HBI scores; 2) assess the change in precipitation and temperature in the study area for the past 30 years; and 3) to document baseline data for the climate change study using bioindicators. Multi habitat sampling (MHS) method was used for the collection of BMI.
In the last 30 years, there was an increment in the temperature and precipitation. Due to alter in the climate drivers there were changes in the ecosystem. Benthic macroinvertebrates responded well to the change. There was a strong positive correlation between altitude and EPT taxa richness. However, there was strong negative correlation between temperature and EPT taxa richness. The EPT and diptera composition of lower altitude resembles the higher sites; this similarity in taxa composition of macroinvertebrate indicates the taxa shifting to higher altitude. The EPT taxa abundance and diversity was higher in all the sites; and OCH abundance and diversity was gradually decreasing with the increase in altitude. Benthic Macroinvertebrates (BMI) such as Leptophlebiidae, Perlodidae, Limoniidae, Planariidae Empididae, Capniidae, Rhyacophilidae, and Brachycentridae were observed as temperature sensitive taxa and BMI such as Baetidae, Simuliidae, Chironmidae, and Tipulidae were observed as the temperature tolerant.