Research project: Indian aquatic ecosystems – impact of deoxygenation, eutrophication and acidification

Project leader: Naqvi, S.W.A.

Objectives:

  • To understand processes responsible for formation of oxygen minimum zones in the North Indian Ocean and to evaluate the extent of ongoing changes in oxygen
  • distribution in the region through observations and modeling.
  • To establish trends in changes in seawater pH in the North Indian Ocean and evaluate the impact of acidification on biogeochemistry and ecosystems.
  • To understand the fate of fertilizers, especially nitrogen, in terrestrial ecosystems in order to evaluate their fluxes to the ocean and consequent modification of coastal
  • biogeochemistry and ecology.
  • To improve the understanding of OMZ processes such as redox transformations of biogenic elements and their interactions, microbial ecology, trophic transfers in lowoxygen waters, and effect of oxygen deficiency on benthic processes, and to evaluate the current and future impacts of human activities on these processes.
  • To reconstruct paleo-redox conditions from sedimentary record from the Indian continental margin.

Abstract:
Aquatic ecosystems face three major threats from human activities: (1) Uptake of CO2 released to the atmosphere due to anthropogenic activities is lowering water pH (acidification), which will have negative effects on calcification, metabolism, fertility, survival and growth of organisms; (2) High nutrient loading (eutrohication) is stimulating plant/algal growth in both freshwater and coastal marine systems; and (3) A combination of slower ventilation and greater oxygen demand in subsurface waters is resulting in an expansion of oxygen minimum zones in the open ocean and appearance of hundreds of hypoxic sites in coastal areas. These alterations in aquatic biogeochemistry and ecosystems are expected to have a profound impact on water quality and living resources (biodiversity and fisheries) besides providing feedback to global change. Such changes are of special relevance to India because (a) natural processes make aquatic environments in and around India extremely sensitive to human perturbations; and (b) the magnitude of anthropogenic perturbations through drivers such as population increase, industrial growth and land use changes including agriculture that leads to massive release of fertilizers to the environment is much larger in South Asia than in most other geographical areas. Aiming to evaluate the combined effect of the three drivers, this project will focus on relevant biogeochemical and ecological processes across various landscapes and seascapes – from freshwater systems on land to open ocean. The project will have a freshwater component and an oceanic component. The freshwater component will focus on nutrient over-enrichment (eutrophication), especially on the nitrogen cycle, in groundwater, selected natural lakes and man-made reservoirs.

This information is completely missing from the Indian freshwater systems. The oceanic component will deal with the naturally-formed oxygen-minimum zones (OMZs) both in coastal and offshore areas. These environments, that are also characterized by naturally-low pH conditions, are being affected by eutrophication as well, especially in coastal regions. Thus, in such systems, eutrophication, deoxygenation and acidification are expected to interact with each other to produce greatly amplified impact on marine biogeochemistry and ecology. Some important issues that this project will address for the first time are (a) Factors responsible for formation of OMZs and prediction of future changes in their intensity due to global warming and eutrophication; (b) Trends of acidification and its impact on biogeochemistry and ecosystems; (c) Benthic ecology and benthic-pelagic coupling over the continental margin in contact with OMZ; (d) Ecology of the suboxic zone and production and consumption of organic matter, and characterization of the organisms using microscopic and molecular techniques; (e) Links between redox cycles of important biogenic elements (such as nitrogen sulphur and iron); and (f) Reconstruction of past changes in the environment, using high resolution cores and corals.

The project will be implemented as a CSIR Network project involving NIO, National Geophysical Research Institute (NGRI), Centre for Cellular & Molecular Biology (CCMB) and CSIR Centre for Mathematical Modelling and Computer Simulation (CMMACS). It will involve field observations on cruises and through deployment of automated instrumentation (mooring, floats, autonomous vehicles, etc) as well as experiments (laboratory as well as mesocosm). These will be complimented by mathematical modelling.

Concept:
Aquatic ecosystems face three major threats from human activities: (1) Uptake of large amount of CO2 released to the atmosphere due to anthropogenic activities is lowering water pH (acidification), which will have negative effects on calcification, metabolism, fertility, survival and growth of organisms; (2) High nutrient loading (eutrophication) is stimulating plant/algal growth in both freshwater and coastal marine systems; and (3) A combination of slower ventilation and greater oxygen demand in subsurface waters is resulting in an expansion of oxygen minimum zones in the open ocean and appearance of hundreds of hypoxic sites in coastal areas. These alterations in aquatic biogeochemistry and ecosystems are expected to have a profound impact on water quality and living resources (biodiversity and fisheries) besides providing feedback to global change. Such changes are of special relevance to India because (a) natural processes make aquatic environments in and around India extremely sensitive to human perturbations (e.g. about 2/3 of the total global continental margin area exposed to dissolved oxygen < 0.2 ml/l is found in the seas around India); and (b) the magnitude of anthropogenic perturbations through drives such as population increase, industrial/economic growth and land use changes including agriculture that leads to massive release of fertilizers to the environment) is much larger in South Asia than in most other geographical areas. Aiming to evaluate the combined effect of deoxygenation, eutrophication and acidification, this project will focus on relevant biogeochemical and ecological processes across various landscapes and seascapes – from freshwater systems on land to open ocean.

Relevance :
This project will for the first time attempt to investigate and link processes in aquatic systems on land and in the sea. Despite the huge human perturbation on land (e.g. massive use of fertilizers), freshwater systems of India have not been systematically studied so far. Moreover, the impact of ocean acidification and its interaction with deoxygenation are important emerging topics that remain hitherto poorly investigated in the oceans as a whole and the North Indian Ocean in particular.

Envisaged Outputs:
Scientific Knowledge Creation:
The project aims at improving our understanding of current biogeochemical processes and ecosystem functioning and how these are going to be affected by human activities. There are two types of outputs expected from the project:
(a) Advancement of science – results will be published in peer-reviewed international journals (target about 50 papers); and (b) Models for prediction of future changes, which will be used to offer advice to policy makers on possible measures to be taken for addressing issues arising from such changes.

Technology Development:
It is expected that new technology will be developed in the next few years to observe the oceans at a higher spatial and temporal resolution. Automation of measurements is including increasingly larger number of parameters with constantly improved accuracy and precision. The technology for carrying out experiments in reasonably large (mesocosm) set ups in situ has also developed rapidly in recent years, and this project will use many of such advanced instrumentation.

Envisaged Outcomes:
(a) Capacity building in climate change research
(b) Generation of new knowledge on biogeochemical cycling and ecosystem functioning in low-oxygen waters
(c) Assessment of ongoing changes in the water quality and health of aquatic ecosystems (both on land and in the sea) including impact on fisheries and biodiversity
(d) Models to predict future responses of regional biogeochemistry and ecosystems to various scenarios of global change
(e) Advisory to policy makers on possible mitigation measures.

National Institute of Oceanography, India. Project description.


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