10.7 Conclusions and Suggestions
Quantitative estimation of ecosystem-level responses against increasing human
perturbations has become a growing research area in aquatic pollution control.
However, despite urgent need, only few studies so far are available providing a
universal index able to quantify holistic changes in the water quality. Studies
conducted on the Ganga River generally consider parameters bifurcating eutrophy
and metal pollution and, in most cases, without considering ecosystem-level consequences. A critical analysis of available studies/data and emerging trends leads to the
following conclusions/suggestions to cue management strategies on the Ganga
River:
1. Future research needs to focus on the changing state of ecosystem functions
coupling human perturbations with ecosystem feedbacks such as denitrification,
sediment-P and sediment-metal release, and ecological assimilation capacity of
the Ganga River.
2. Because in human-impacted rivers eutrophication and metal pollution generally
occur simultaneously, multi-temporal and multi-scale data base is needed for
understanding ecosystem responses coupling eutrophy and metal pollution in the
river.
3. The wastewater treatment technologies, available so far, generally address
removal of biological oxygen demand (BOD) only. Because the increasing load
of other oxygen-demanding substances (ODS) is contributing substantially to
dissolved oxygen deficit (DOD) causing a greater pressure on overall dissolved
oxygen (DO) levels, these need proper control and management. Also, advance
metal removal technologies are needed because metal pollution in the river is
continuing to rise.
4. Because sediment-based biomonitors are relatively stable and because microbial
extracellular enzymes (EE) respond concordantly to carbon and metal enrichment, the EE activities such as β-D-glucosidase and FDAase can be a good
indicator of river responses toward metal pollution and C eutrophy.
5. Shifts in nutrient stoichiometry can be used as an alternative response indicator of
shifting ecosystem structure and functioning, driven by increasing anthropogenic
perturbations. Diatom ecological guilds, rather than individual species, can be
used as a holistic indicator of short-term disturbances in the aquatic environment.
Initiatives can be taken to enhance micro-niches to increase the diversity of
diatoms, the most important water purifiers in the Ganga River. Furthermore,
because the production of transparent exopolymeric particles (TEP) is maintained
partly by changes in diatom dominance-diversity linkages, the TEP coupled
diatom dominance transference can be used as a key node to cue nutrient
pollution and ecological assimilation capacity of the river.
Acknowledgments We acknowledge CSIR, New Delhi, India, for financial report as fellowship to
DJ.
10 Ecosystem Responses to Pollution in the Ganga River: Key Issues to Address. . .
245
Quantitative estimation of ecosystem-level responses against increasing human
perturbations has become a growing research area in aquatic pollution control.
However, despite urgent need, only few studies so far are available providing a
universal index able to quantify holistic changes in the water quality. Studies
conducted on the Ganga River generally consider parameters bifurcating eutrophy
and metal pollution and, in most cases, without considering ecosystem-level consequences. A critical analysis of available studies/data and emerging trends leads to the
following conclusions/suggestions to cue management strategies on the Ganga
River:
1. Future research needs to focus on the changing state of ecosystem functions
coupling human perturbations with ecosystem feedbacks such as denitrification,
sediment-P and sediment-metal release, and ecological assimilation capacity of
the Ganga River.
2. Because in human-impacted rivers eutrophication and metal pollution generally
occur simultaneously, multi-temporal and multi-scale data base is needed for
understanding ecosystem responses coupling eutrophy and metal pollution in the
river.
3. The wastewater treatment technologies, available so far, generally address
removal of biological oxygen demand (BOD) only. Because the increasing load
of other oxygen-demanding substances (ODS) is contributing substantially to
dissolved oxygen deficit (DOD) causing a greater pressure on overall dissolved
oxygen (DO) levels, these need proper control and management. Also, advance
metal removal technologies are needed because metal pollution in the river is
continuing to rise.
4. Because sediment-based biomonitors are relatively stable and because microbial
extracellular enzymes (EE) respond concordantly to carbon and metal enrichment, the EE activities such as β-D-glucosidase and FDAase can be a good
indicator of river responses toward metal pollution and C eutrophy.
5. Shifts in nutrient stoichiometry can be used as an alternative response indicator of
shifting ecosystem structure and functioning, driven by increasing anthropogenic
perturbations. Diatom ecological guilds, rather than individual species, can be
used as a holistic indicator of short-term disturbances in the aquatic environment.
Initiatives can be taken to enhance micro-niches to increase the diversity of
diatoms, the most important water purifiers in the Ganga River. Furthermore,
because the production of transparent exopolymeric particles (TEP) is maintained
partly by changes in diatom dominance-diversity linkages, the TEP coupled
diatom dominance transference can be used as a key node to cue nutrient
pollution and ecological assimilation capacity of the river.
Acknowledgments We acknowledge CSIR, New Delhi, India, for financial report as fellowship to
DJ.
10 Ecosystem Responses to Pollution in the Ganga River: Key Issues to Address. . .
245