Environmental Engineering Reference
In-Depth Information
regulated in the foothill stretch between Rishikesh
and Hardwar.
patterns in the various subbasins of the western
Himalaya. The count data is subjected to cluster
analysis (statistic aver. 5.0) and multivariate
analysis using software (ter Braak and Smilauer
2002
).
Physical and Chemical
Characteristics of Rivers
Benthic Invertebrate Fauna
and Communities in Different
River Basins
The benthic macroinvertebrate assemblages are
represented by 31 taxa (families) from 6 insect
and 1 gastropod order. The majority of insect
taxa belonged to the order Trichoptera (8 families)
and Ephemeroptera (6 families), followed by
Coleoptera (5 families), Diptera (4) and
Plecoptera (2), while the gastropod are repre-
sented by 2 families (order Basommatophora).
Ephemeroptera, Trichoptera, Diptera and
Plecoptera are the major components of the benthic
macroinvertebrate community in the mountain
streams (Hynes
1970
; Winterbourn and Ryan
1994
), as also observed earlier in the rivers of
Himalaya, Alaknanda (its tributary Khanda
Gad), Bhagirathi and Ganga (Nautiyal
1986
;
Singh and Nautiyal
1990
; Kumar
1991
; Singh
et al.
1994
; Nautiyal et al.
1997a
,
2004
) and the
Central Highlands, Ken, Paisuni and Tons
(Nautiyal et al.
2007
).
Among the invertebrate orders the relative
abundance of Trichoptera is relatively higher
in all the basins. Highest abundance is recorded
for Pindar (45 %), followed by Alaknanda
(41 %), Mandakini (39 %), Bhagirathi (39 %),
Ramganga (32 %) and Yamuna (31 %;
Fig.
4.2
). Notably, instead of a similar share of
Trichoptera in the benthic community or gra-
dient of increase or decrease from east to west
or vice versa, their share (relative abundance)
is considerably higher in the basins located
between the Ramganga and Yamuna. Among
the basins Trichoptera is the abundant taxon
in all streams/rivers of the Pindar, Alaknanda,
Bhagirathi (except Dharasu), Mandakini
(except Damar) and Ramganga basins.
However, in the Yamuna basin, Trichoptera is
abundant in the Yamuna and Tons tributary at
Naitwar and Ephemeroptera in the Rupin and
Tons, while Ephemeroptera and Trichoptera
The following characteristics are recorded:
Map variables
: Latitude (N°), altitude (metre;
above sea level), slope (metre), vegetation,
land use, distance to source (metre).
Site variables
: Stream width (m), mean current
velocity (ms
−1
), mean depth (m), substrate,
solar radiation, water temperature, pH, dissolved
oxygen, and aquatic vegetation. The air and
water temperature are recorded with the help
of a mercury thermometer and compared with
the help of a digital temperature probe. Flow
is measured with the help of digital EMCON
current metre. pH is measured with the help of
digital pocket pH metre and DO is measured
with the help of Aquamerck kit and verifi ed by
titrimetric Winkler's method.
Sampling: Benthic
Macroinvertebrate Fauna
Benthic macroinvertebrates are sampled in 5
quadrates of 1 ft
2
each. The substratum in the
form of small boulders, cobbles and pebbles is
lifted carefully from the marked area and washed
in a bucket full of water by dipping it a number of
times to dislodge the attached fauna. The fauna
that remained attached to the substrate surface is
removed with the help of brush. The bucket water
is fi ltered through a 0.5 mm sieve to retain ben-
thic macroinvertebrates (Singh and Nautiyal
1990
; Habdija et al.
1997
). The samples are pre-
served in 5 % formalin for further analysis.
Various benthic taxa are identifi ed to family level
with the help of different keys (Burks
1953
;
Pennak 1953; Edmundson et al.
1976
; Macan
1979
). Family-level studies have been successfully
used to describe biogeographical patterns across
large areas (Corkum
1989
). Relative abundance
of various taxa at above-stated sites during each
month is computed as percentage of total benthic
macroinvertebrate count from fi ve samples to
determine the macro- and microdistribution
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