FISH DIVERSITY OF RAPTI RIVER, CHITWAN, NEPAL
Date
2023-08-17
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Publisher
Amrit Campus
Abstract
The present study was conducted in Rapti River of Chitwan District located between
latitudes of 27°20’ to 27°52’N and longitudes of 83°55’ to 84°52’E. The field visit was
conducted from 23rd February to 28th June, 2020. Samples were collected from four
stations, i.e. Manahari, Lothar, Kumroj and Sauraha for fishes and physicochemical
parameters such as water temperature, DO, water velocity and pH. Fishes were
collected with the help of well-trained local fisherman, by using a cast net of varying
mesh sizes (6mm, 2cm). A total of 36 fish species were collected belonging to 5 orders,
11 families and 24 genera. The Cypriniformes was the dominant order with 24 species
representing 65.71% of the total collection, followed by Siluriformes (8 species,
22.85%) and Anabantiformes (2 species, 5.7%). Each of Beloniformes and
Synbranchiformes was collected a single species representing 2.85 % respectively. The
highest species richness (9) was recorded at Kumroj and lowest species (3) at Manahari
in rainy season. Similarly, the highest species richness (8) was recorded at Manahari
and the lowest species (4) at Sauraha in winter season. The Shannon-Wiener’s diversity
index was high at Kumroj (1.588) and low at Manhari (1.055) in rainy season. It is high
at Kumroj (1.588) and low at Lothar (1.298) in winter. In rainy season, the highest
Simpson diversity index (0.75) was found at Sauraha and the lowest (0.611) was at
Lothar. In winter, the highest Simpson diversity index (0.768) was found at Kumroj
and the lowest (0.702) was at Lothar. In rainy season, the highest Margalef’s index
(2.09) was found in Kumroj and the lowest (1.243) was at Manhari. In winter, the
highest Margalef’s index (2.164) was found at Sauraha and the lowest (0.965) was
found at Lothar. Dissolved oxygen was recorded as the highest (11.5 mg/l) at Manhari
and lowest (8.3 mg/l) at Sauraha in winter season. The dissolved oxygen was
comparatively lower in rainy season which ranged from 7.4 mg/l (Sauraha) to 9.8 mg//l
(Lothar). The Redundancy Analysis (RDA) showed a strong positive association
between species like Barilius barila, B. bendelisis, B. modestus, C. jaya, and T. tor with
DO. C. chagunio was found to be negatively associated with pH and the remaining
species however showed the average association. It is evident that systematic research
on regular interval of time basis is crucial to have more reliable data on fish diversity
status. Long term research covering more seasons and more water quality parameters
is highly recommended in this river in future.
Description
Keywords
Diversity index, Fish fauna, Rapti River, Water quality