Spatio Temporal Variation in the Fish Assemblance Structure of the Mechi River Eastern Nepal

Abstract

Species diversity is widely recognized as an important trait of ecosystem functioning and resilience. Spatio-temporal patterns of fish assemblage structure in Mechi River were studied based on Stratified random survey conducted during September 2108 to April 2019. The survey was conducted on three different sampling stations at three different seasons. The spatial and temporal patterns of fish assemblage were analyzed by using Shannon Weinner index, the Simpson index and evenness. To examine the fish assemblage structure, fish samples were collected in seasonal basis from three sites of the River by using cast net and gill net. A total of 1772 individuals belonging to 4 orders, 8 families, 16 genera and 33 species were collected from Salakpur, Gadagalli and Nakalbanda of Mechi River. The most abundant species were Schistura devdevi followed by Puntius sophore and Barilius barila. The highest diversity index (2.93) and Simpson index (0.93) was recorded during winter season for seasonal diversity. The highest diversity index (92.69) and Simpson index (0.9) of fish were recorded from station 2 for the station wise diversity. The CCA analysis (fig.12) showed that the fish assemblage was highly correlated with temperature. Velocity and DO whereas negatively correlated with carbon dioxide and slightly correlated with pH. This study may help to maintain native fish adapted to these conditions in the Mechi River as well as it may help in expansion of knowledge regarding the fish diversity of Nepal.