Status and Human Impact Assessment of Jagdishpur Reservoir - A Ramsar Site, Nepal
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Department of Environmental Science
Abstract
Jagdishpur 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.