through dominance transference. The low-profile guilds representing species such as
Cocconeis placentula, Cymbella affinis, Cyclotella meneghiniana, and Synedra ulna
were found abundantly at P-poor sites, and high-profile guilds representing species
such as Diatoma vulgaris, Gomphonema parvulum, and Fragilaria intermedia were
present at P-rich sites (Pandey et al. 2017).
The excessive nutrient loading alters the diatom dominance pattern (Fig. 10.1 and
Table 10.1), and a marked skewness in diatom dominance-diversity linkages has
been observed in the Ganga River (Pandey et al. 2017). The synchrony between
skewness and altered water quality shows the ability of diatoms to cope with nutrient
stressors and disturbances. Among the TEP producers, species such as Cocconeis
placentula, Cyclotella meneghiniana, and Cymbella affinis have been reported to
flourish at nutrient-poor sites, while Aulacoseira granulata, Diatoma vulgaris,
Melosira varians, and Fragilaria intermedia show extensive growth in nutrientrich condition (Pandey et al. 2017; Fig. 10.2). These results indicate that the diatom
ecological guilds can be used as holistic and alternative indicators of short-term
changes or disturbances in the aquatic environment. Additionally, the dependence of
TEP on Chl a biomass and N/P stoichiometry makes it an indicator of trophic status
and nutrient pollution. Because the TEP production is maintained partly by changes
in diatom dominance-diversity linkages despite variable ecological conditions and
human perturbations, the TEP coupled diatom dominance transference can be used
as a key node to cue nutrient pollution and ecological assimilation capacity of
anthropogenically impacted large rivers.
10.6.4 Ecological Response Index
Quantitative estimation of ecosystem responses against increasing human perturbations has become a growing research area in aquatic pollution control. Despite urgent
need, only few studies so far are available, providing a universal index to quantify
holistic changes in the water quality (Satyamurthy 2017). For a universal applicability, an index should have intricate links with ecosystem structure and functioning
(Peterson and Stevenson 1992). Sediment-based biomonitoring tools are now being
suggested to be more accurate in designing empirical relationships to uncover the
ecosystem responses and magnitude of degradation (Turley et al. 2016; Pandey and
Yadav 2017).
For lotic ecosystems, where hydrologic forcing drives unpredictability, selecting
a suitable response variable is difficult. There is no study so far available, except
Jaiswal and Pandey (2019a), linking simultaneously the carbon-heavy metal-ecosystem responses to quantitatively predict the human-driven alterations in large
rivers (Table 10.2). The indices developed so far for the assessment of pollution
load, toxicity, and trophic status, such as enrichment factor (Buat-Menard and
Chesselet 1979), trophic state index (Carlson 1977), potential ecological risk index
(Håkanson 1980), pollution load index (Tomilson et al. 1980), pollution index
(Nemerow 1991), and geoaccumulation index (Müller 1969), consider the
10 Ecosystem Responses to Pollution in the Ganga River: Key Issues to Address. . .
241
Cocconeis placentula, Cymbella affinis, Cyclotella meneghiniana, and Synedra ulna
were found abundantly at P-poor sites, and high-profile guilds representing species
such as Diatoma vulgaris, Gomphonema parvulum, and Fragilaria intermedia were
present at P-rich sites (Pandey et al. 2017).
The excessive nutrient loading alters the diatom dominance pattern (Fig. 10.1 and
Table 10.1), and a marked skewness in diatom dominance-diversity linkages has
been observed in the Ganga River (Pandey et al. 2017). The synchrony between
skewness and altered water quality shows the ability of diatoms to cope with nutrient
stressors and disturbances. Among the TEP producers, species such as Cocconeis
placentula, Cyclotella meneghiniana, and Cymbella affinis have been reported to
flourish at nutrient-poor sites, while Aulacoseira granulata, Diatoma vulgaris,
Melosira varians, and Fragilaria intermedia show extensive growth in nutrientrich condition (Pandey et al. 2017; Fig. 10.2). These results indicate that the diatom
ecological guilds can be used as holistic and alternative indicators of short-term
changes or disturbances in the aquatic environment. Additionally, the dependence of
TEP on Chl a biomass and N/P stoichiometry makes it an indicator of trophic status
and nutrient pollution. Because the TEP production is maintained partly by changes
in diatom dominance-diversity linkages despite variable ecological conditions and
human perturbations, the TEP coupled diatom dominance transference can be used
as a key node to cue nutrient pollution and ecological assimilation capacity of
anthropogenically impacted large rivers.
10.6.4 Ecological Response Index
Quantitative estimation of ecosystem responses against increasing human perturbations has become a growing research area in aquatic pollution control. Despite urgent
need, only few studies so far are available, providing a universal index to quantify
holistic changes in the water quality (Satyamurthy 2017). For a universal applicability, an index should have intricate links with ecosystem structure and functioning
(Peterson and Stevenson 1992). Sediment-based biomonitoring tools are now being
suggested to be more accurate in designing empirical relationships to uncover the
ecosystem responses and magnitude of degradation (Turley et al. 2016; Pandey and
Yadav 2017).
For lotic ecosystems, where hydrologic forcing drives unpredictability, selecting
a suitable response variable is difficult. There is no study so far available, except
Jaiswal and Pandey (2019a), linking simultaneously the carbon-heavy metal-ecosystem responses to quantitatively predict the human-driven alterations in large
rivers (Table 10.2). The indices developed so far for the assessment of pollution
load, toxicity, and trophic status, such as enrichment factor (Buat-Menard and
Chesselet 1979), trophic state index (Carlson 1977), potential ecological risk index
(Håkanson 1980), pollution load index (Tomilson et al. 1980), pollution index
(Nemerow 1991), and geoaccumulation index (Müller 1969), consider the
10 Ecosystem Responses to Pollution in the Ganga River: Key Issues to Address. . .
241