Browsing by Subject "Benthic macroinvertebrates"
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Item Diversity and Distribution Patterns of Freshwater Macroinvertebrates in Modi River System, Gandaki Province, Nepal(Department of Botany, 2022) Ghimire, BabitaIn the face of several stressors in Modi River system, this research was conducted with the aim of assessing diversity and distribution patterns of benthic macroinvertebrates along the altitudinal gradient including the ecological health of a River system. Benthic macroinvertebrates sampling was conducted in 20 different (13-river's mainstem and 7- tributaries) following a multi-habitat sampling approach based on Moog (2007). Macroinvertebrates were collected by kicking the substrate or jabbing with a D-frame dip net and transferred into labeled vials and preserved in 99.9% ethanol for sorting and identification in the lab. Threats were identified from direct observation and key informant interview. Taxa richness was assessed using Shannon Diversity Index, Simpson Diversity Index, and Evenness. Similarly, Shapiro-Wilk normality test, One way ANOVA, Turkey HSD test and Wilcoxon pair test were conducted to know the difference between groups. R studio (1.2.5 version) and CANOCO (4.5 version) was used for statistical analysis. In total, 40 families belonging to 10 orders were recorded in the study area. 29 families belonging to eight orders were recorded in river’s mainstem while 39 families belonging to 9 orders were recorded in tributaries. Lowest numbers of taxa were recorded at higher elevations of both river (9 families at 1654m) and tributaries (14 families at 1719m). Among 40 families, order Diptera has the highest family richness. Turkey HSD test showed taxa richness between 1550-1800m and 1050-1300m (p=0.0004), and 15501800m and 1350-1500m (p=0.0389) differ significantly. Taxa richness is highest at the elevation of 1050-1300m and lowest at 1550-1800m. Similarly, Shannon Diversity index is highest in the sampling sites located at 1265m elevation and lowest at 1533m. Test Showed that the diversity index differs significantly (p=0.049) with altitude. Wilcoxon pair test did not show the difference in the Simpsons Diversity Index between river's mainstem and tributaries (p=0.195). Likewise, RDA diagram showed the temperature as the most important variable governing the BMI composition . Furthermore, river's mainstem are less polluted than the tributaries. Hydropower construction, sewage, sand and stone quarry, waste dumping, bathing and washing were the major threats for the river system. Keywords: Benthic macroinvertebrates, freshwater, diversity, distribution, stressorsItem Status and Human Impact Assessment of Jagdishpur Reservoir - A Ramsar Site, Nepal(Department of Environmental Science, 2010) Dhonju, ManglesworiJagdishpur Reservoir is one of the most important wetland of Nepal designated as Ramsar Site in 2003. It is also highlighted in the Directory of Asian Wetlands. A very few attempts have been made to evaluate the ecological quality of wetlands using benthic macroinvertebrates as scientific parameters for water quality, spatio-temporal variation of benthic community and their relationship with environmental parameters. In this connection, this study was intended to determine the ecological status and analyze seasonal variation of the benthic fauna in relation to environmental variables. Social survey was also conducted around the settlement areas in order to know human impact on the reservoir. The study was conducted for one year period from September 2008 to August 2009. Field study and samplings were carried out in three season i.e. post-monsoon (November, 2008), pre-monsoon (April, 2009) and monsoon (July, 2009). In total, twelve samples from littoral zone, fourteen samples from profundal zone, three samples from inlet and five samples from outlets of the reservoir were taken. Similarly, four samples were taken from the littoral zones of surrounding wetland. Shannon’s diversity index (H’) and Piélou’s evenness index (e) were used to determine taxa richness while GRS-BIOS was used to determine the ecological quality class of the study site. Canonical Correspondence Analysis (CCA) was carried out for investigation of direct relationship between macroinvertebrate assemblages and environmental variables. Spearman correlation coefficients between environmental variables were determined and significant differences in taxa richness (no. of taxa) and density among different zones of wetlands were conducted by using One Way ANOVA from package R 2.9 versions. Altogether 50, 53 and 42 macroinvertebrates taxa were recorded from reservoir (littoral and profundal zone), inlet and outlets and littoral zone of surrounding wetlands respectively. Likewise 46, 38 and 38 taxa with an average density of 230 ind./m , 391 ind./m 2 and 346 ind./m 2 were recorded from the reservoir (including littoral and profundal zone) in post-monsoon, pre-monsoon and monsoon season respectively. The study showed significant difference in taxa composition number and density among different zones (Littoral, Profundal and Littoral zones of surrounding wetlands) of Jagdishpur reservoir for all season. The Jagdishpur reservoir including its inlet, outlets, and surrounding wetlands was categorized as 'Quality class IV' and described as poor quality. The GRS BIOS/ASPT for all sample sites ranged between 2.50 and 3.99. Canonical correspondence analysis (CCA) resulted that faunal assemblages and composition structures were influenced by different environmental variables depending on season for same wetland zone/type and was not possible to draw concrete and general result for particular zone/type of wetlands for overall year. The number of taxa differed significantly among different zones of the reservoir in all three seasons as given by One Way ANOVA analysis. The spearman correlation analysis for all season showed significant positive correlation between number of taxa and abundance. Human activities like commercial fish farming, excessive use of pesticides and fertilizers, bathing and washing clothes aggravate deteriorating ecological condition of reservoir. The present study helps to give status of benthic macroinvertebrates of Jagdishpur reservoir. The outcomes can be widely applied to assess Nepalese lentic ecosystems.