41
Glossosomatidae and Baetidae in the Mandakini,
Glossosomatidae and Heptageniidae in the Pindar
and Simuliidae and Heptageniidae in the Ramganga
(Table 4.3 , Plate 4.1 ).
This change is due to reduction in food particle size from CPOM (coarse particulate organic
matter) to FPOM (fi ne particulate organic matter)
as the stream fl ows down from the origin. The
oak forest is characterised by the shredders
(Lepidoptera) and fi lterers (Simuliidae), which
feed on CPOM and FPOM. Pine forest type is
characterised by the scrapers (Blephariceridae,
Limnephilidae), predators and gatherers
(Ephemerellidae, Baetidae, Hydropsychidae)
and fi lterers (Planorbidae, Lymnaeidae) which
feed on periphyton, CPOM and FPOM, respectively. The pine–oak forest type is characterised
by the scrapper (Elmidae, Dryopidae) and predator (Rhyacophilidae, Agrionidae), which feed on
periphyton and CPOM, respectively. The forest
types are known to govern the characteristic taxa
in the streams draining them (Corkum 1992 ;
Sivaramakrishanan et al. 1995 ).
By virtue of low nutrient concentration near
the origin and headwater zone, the algal (primarily diatom) density (Nautiyal et al. 1997b ) and
hence their biomass and the primary production
are low. The streams are thus largely heterotrophic in this zone and tend to become autotrophic
towards the middle and lower zones near the
foothills (Welcomme 1985 ; Cotta Ramusino
et al. 1995 ). Headwater streams are heavily infl uenced by riparian vegetation, which is responsible for large-scale inputs of allochthonous
nutrients while at the same time hindering autotrophic production by shading (Welcomme
1985 ). Owing to allochthonous nutrients in the
headwaters, the detritus-feeding Trichoptera
which function as shredders, gatherers and collectors are predominant.
The abundance of both Trichoptera and
Ephemeroptera increased gradually from the
eastern (the Ramganga) to the western river
basins (the Bhagirathi), but declined further in
the Yamuna basin where Diptera increased marginally. This pattern in the change of taxonomic
composition may be explained by the prevailing
forest types in the respective basins from east to west,
i.e. pine (Ramganga and Pindar), pine–oak–meadow
(Alaknanda and Mandakini), pine–oak–deodar
(Bhagirathi) and oak–deodar–fi r (Yamuna). In all
these forest types only the families functioning as
shredders, collectors, gatherers and fi lterers in
the case of Trichoptera and collectors, gatherers,
fi lterers and scrapers in the case of Ephemeroptera
are abundant. The lattermost (scraper) is least
abundant in the system indicating low autochthonous inputs and thus low levels of autotrophy. In
all the basins Trichoptera and Ephemeroptera are
followed by Diptera. Diptera increased in the
Yamuna basin due to forest–agriculture land use,
which may provide more FPOM necessary for
the development of fi lterers.
Classifi cation of the Basins Based
on Invertebrate Faunal Composition
The cluster analysis revealed two broad groups
among the river basins with respect to taxonomic
composition observed in them. The fi rst group
comprised Mandakini and Bhagirathi, while
the second cluster included three subgroups the
Pindar, Yamuna–Ramganga and Alaknanda. The
subclusters explained the grouping of similar
streams. The Bhilangana (B5–B6), though a tributary of the Bhagirathi, clumped with Pindar.
The Alaknanda is the third group (Fig. 4.4 ). The
cluster also grouped together sites with similar
forest and land use.
The cluster analysis revealed close similarity
in the taxonomic composition (family level) of
the Mandakini–Bhagirathi basin. There is weak
similarity among the Ramganga and Yamuna
basins, while the Pindar and Alaknanda basins
are opposite extremes in this loose grouping.
This suggests that similarity among the adjacent
basins is not a rule and even distant basins can be
similar. The similarity between the adjacent
Mandakini and Bhagirathi basin due to identical
climatic conditions supports the hypothesis that
the localities in close proximity should be similar. The similarity among the distantly located
basins, Ramganga (eastern extreme of
Uttarakhand) and Yamuna (western extreme of
Uttarakhand), and their similarity to the
4 Spatial Distribution of Benthic Macroinvertebrate Fauna
Glossosomatidae and Baetidae in the Mandakini,
Glossosomatidae and Heptageniidae in the Pindar
and Simuliidae and Heptageniidae in the Ramganga
(Table 4.3 , Plate 4.1 ).
This change is due to reduction in food particle size from CPOM (coarse particulate organic
matter) to FPOM (fi ne particulate organic matter)
as the stream fl ows down from the origin. The
oak forest is characterised by the shredders
(Lepidoptera) and fi lterers (Simuliidae), which
feed on CPOM and FPOM. Pine forest type is
characterised by the scrapers (Blephariceridae,
Limnephilidae), predators and gatherers
(Ephemerellidae, Baetidae, Hydropsychidae)
and fi lterers (Planorbidae, Lymnaeidae) which
feed on periphyton, CPOM and FPOM, respectively. The pine–oak forest type is characterised
by the scrapper (Elmidae, Dryopidae) and predator (Rhyacophilidae, Agrionidae), which feed on
periphyton and CPOM, respectively. The forest
types are known to govern the characteristic taxa
in the streams draining them (Corkum 1992 ;
Sivaramakrishanan et al. 1995 ).
By virtue of low nutrient concentration near
the origin and headwater zone, the algal (primarily diatom) density (Nautiyal et al. 1997b ) and
hence their biomass and the primary production
are low. The streams are thus largely heterotrophic in this zone and tend to become autotrophic
towards the middle and lower zones near the
foothills (Welcomme 1985 ; Cotta Ramusino
et al. 1995 ). Headwater streams are heavily infl uenced by riparian vegetation, which is responsible for large-scale inputs of allochthonous
nutrients while at the same time hindering autotrophic production by shading (Welcomme
1985 ). Owing to allochthonous nutrients in the
headwaters, the detritus-feeding Trichoptera
which function as shredders, gatherers and collectors are predominant.
The abundance of both Trichoptera and
Ephemeroptera increased gradually from the
eastern (the Ramganga) to the western river
basins (the Bhagirathi), but declined further in
the Yamuna basin where Diptera increased marginally. This pattern in the change of taxonomic
composition may be explained by the prevailing
forest types in the respective basins from east to west,
i.e. pine (Ramganga and Pindar), pine–oak–meadow
(Alaknanda and Mandakini), pine–oak–deodar
(Bhagirathi) and oak–deodar–fi r (Yamuna). In all
these forest types only the families functioning as
shredders, collectors, gatherers and fi lterers in
the case of Trichoptera and collectors, gatherers,
fi lterers and scrapers in the case of Ephemeroptera
are abundant. The lattermost (scraper) is least
abundant in the system indicating low autochthonous inputs and thus low levels of autotrophy. In
all the basins Trichoptera and Ephemeroptera are
followed by Diptera. Diptera increased in the
Yamuna basin due to forest–agriculture land use,
which may provide more FPOM necessary for
the development of fi lterers.
Classifi cation of the Basins Based
on Invertebrate Faunal Composition
The cluster analysis revealed two broad groups
among the river basins with respect to taxonomic
composition observed in them. The fi rst group
comprised Mandakini and Bhagirathi, while
the second cluster included three subgroups the
Pindar, Yamuna–Ramganga and Alaknanda. The
subclusters explained the grouping of similar
streams. The Bhilangana (B5–B6), though a tributary of the Bhagirathi, clumped with Pindar.
The Alaknanda is the third group (Fig. 4.4 ). The
cluster also grouped together sites with similar
forest and land use.
The cluster analysis revealed close similarity
in the taxonomic composition (family level) of
the Mandakini–Bhagirathi basin. There is weak
similarity among the Ramganga and Yamuna
basins, while the Pindar and Alaknanda basins
are opposite extremes in this loose grouping.
This suggests that similarity among the adjacent
basins is not a rule and even distant basins can be
similar. The similarity between the adjacent
Mandakini and Bhagirathi basin due to identical
climatic conditions supports the hypothesis that
the localities in close proximity should be similar. The similarity among the distantly located
basins, Ramganga (eastern extreme of
Uttarakhand) and Yamuna (western extreme of
Uttarakhand), and their similarity to the
4 Spatial Distribution of Benthic Macroinvertebrate Fauna