Browsing by Subject "Freshwater"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Effects of Dichlorvos on Freshwater Fish Rohu (Labeo rohita Hamilton,1822)(Department of Zoology, 2021) Sapkota, BhawaniPesticides are applied to control the pests indoor and outdoor; however, their remarkable amount reaches the aquatic system through various routes like run-off, leaching, spray-drift, and effluent from factories. These pesticides are reported to have a negative metabolic impact on different non-target aquatic organisms like fishes. Thus, the present study was aimed to evaluate the acute toxicity of commonly used organophosphate pesticide dichlorvos to the freshwater fish Rohu (Labeo rohita). The experimental setup was designed to test the acute toxicity, advanced behaviour, and some haematological as well as biochemical analysis for a period of 96h. The LC₅₀ values for dichlorvos after 96hr treatment was found to be 11.36 mg/L. In treated fish, alterations in various behavioural patterns respiratory metabolism, opercular beat rate, and blood parameters were examined for sub-lethal end-points following 1h, 24 hr, 48 hr, 72 hr, and 96 hr exposure. Accelerated opercular beat rate (P < 0.05) was recorded in pesticide-exposed groups in comparison to control. Though the respiratory metabolism was not significantly affected, an increment in oxygen consumption rate was recorded. The pesticide stress caused a significant elevation in haemoglobin (P < 0.01) whereas total protein content was significantly dropped (P < 0.05). Glucose content was found to be increased (P > 0.05) in the pesticide group, compared to the control. Some general behavioural changes such as erratic movement, gulping, schooling, mucus secretion, equilibrium, aggregating behavior, and paleness in the body were observed in pesticide-exposed fish. The acute toxicity data reported in this study can be used to assess the tolerance level of Rohu to insecticide dichlorvos.Item Species Diversity, Consumption Trends and Conservation Status of Freshwater Molluscs in Ghodaghodi Lake Area, Kailali District, Nepal(Central Departmental of Zoology, 2017) Chaudhary, PoonamThe study deals with diversity, consumption trends and conservation status of freshwater molluscs in Ghodaghodi lake complex and associated lakes, Kailali District, Nepal. Field survey was conducted from March-April 2016. Altogether 17 Molluscan species were revealed from the study area including 13 gastropods and 4 bivalve species. Six Molluscan species viz. Pila globosa, Bellamya bengalensis, B. dissimilis, Brotia costula, Parreysia favidens, Lamellidens marginalis were reported as of food and medicinal value. Most of the people preferred Bellamya spp. followed by Pila sp. and Bivalve spp. large bivalves L. marginalis had restricted distribution and very low population in the study area while Parreysia favidens were collected only from permanent stream. DO (Pr= 0.00965), water temperature (Pr= 0.00257), depth (Pr= 0.02081), and elevation (Pr= 0.06898), Spearmans’s correlation coefficient were found statistically significant on mollusc species by one-way ANOVA. Species diversity was found by Shannon Wiener Diversity Index. Structured interview showed people collect molluscs either by hand picking or by using local tools (Heluka). Consumption trends are increasing by 62 % among Tharu community. People also opined that consumption, poisoning, habitat loss, climate change and pollution as major threats of molluscs.