Dept of Bio-Chemistry

University of Calcutta 

Human dependence on coastal ecosystems is increasing at an unprecedented rate, which is likely to rise to over nine billion by 2050, according to United Nations Population Division. The impacts of human pollution and habitat alteration are most evident and of greatest concern at the microbial level, where a bulk of production and nutrient cycling takes place. Vibrant marine and coastal ecosystems provide valuable services in terms of nutrition security, resources for economic development and restitution to a weary being as he scouts for some places along the shoreline in the quest of tranquillity. The changes in ocean chemistry due to global warming or greenhouse gases will adversely affect the physical and biological characteristics of coastal systems, modifying their ecosystem structure and functioning. As a result, coastal nations face losses of marine biodiversity, fisheries, habitat loss, nutrient pollution, shorelines, etc. unless some scientific intervention is there for restoration of the equilibrium.

The eastern part of the coastal region of West Bengal is characterized by the spectacular mangrove forest of Sundarbans. The forest performs several important ecological functions for its sustenance. On one hand, the mangrove forest acts as a bio-shield against severe storms and cyclones coming from the Bay of Bengal that have the potential of causing large scale damage to the coastal areas. On the other hand, the mangrove forest participates in complex physical, chemical and biological interactions that produce a unique ambience for healthy and luxuriant growth of the forest. People living in and around the forest draw their livelihood from the living and renewable resources provided by the forest. The forest acts as a sink of carbon in as much as it is suspected that they emit methane, a greenhouse gas, to the atmosphere. It is also known that carbon dioxide is produced by heterotrophic activity in a mangrove swamp. However, a correct assessment of the contribution of mangrove forest towards controlling the climate change/global warming is still not available due to absence of reliable measured data. Conversely, the expected changes in carbon bio-geochemical cycle in the mangrove system in relation to the anticipated climate change/global warming are still to be understood due to the aforementioned reasons.

The life forms in the Sundarbans have a complex inter-related existence to maintain equilibrium dynamics within the extant of physical and chemical environment. The mangrove produces rich organic debris (consisting of decaying spores, pollens, seeds, leaves, fruits, twigs and branches of trees, etc.) due to its high biological productivity with unique concentrations of nutrients in the debris.  The nutrients are released both to the water and soil of the mangrove wetland of Sundarbans. Parts of these “foods” are consumed by a group of organisms (like fishes, birds, amphibians, mammals, etc) either directly or through the water or the soil medium to sustain their body metabolic functions. The other parts are assimilated in the substrate soil, “consumed” by various forms of microbes which return some part of the “digested” consumed food to the soil as organic fertilizers. The fertilized soil (humification) thus supports further luxuriant growth of the mangrove forest. There is, however, a residual flow of nutrients and organic carbon from the mangrove system to the coastal water. The microbial diversity of a mangrove forest is mind-boggling and the various forms interact with the environment at various energy levels to set up a complex food web and growth of mangrove vegetation.

Background

It has been noted that the coastal and estuarine wetlands in the Sundarban region are in dire risk due to sea-level rise and saltwater intrusion. The impact of natural and anthropogenic stressors on biogeochemical cycles in coastal and inland wetlands is also taking its toll on the fragile ecosystem of Sundarban as gradually the salinity gradient moved into the saline/tidal marshes, then brackish marshes, freshwater marshes, and ending with freshwater/forested wetlands.

It has been worked out that within the ICZMP, Calcutta University will act as one of the Pilot Investment Executing Agencies that will perform basic research work to explore diversity of microbes in Sundarban and their role on withstanding coastal erosion and other ecological processes, etc. The University of Calcutta is supposed to investigate the following:-

·         Understanding the functioning of the Sundarbans mangrove system through the research on activities of the microbes present in the substrate sediments and understanding the role of microbial diversity in maintaining the system.

·         Understanding the natural process of capture of carbon and emission of greenhouse gases from mangrove forests of Sundarbans thereby assessing the contribution of mangrove forest towards controlling global warming.

·         Predicting the changes in carbon bio-geochemical cycle in the mangrove system of Sundarbans in relation to climate change/global warming.

·         Understanding the natural process of flow of the nutrients and organic carbon from the mangrove system to the coastal sediment and water in Sundarbans to self-support the mangrove system of Sundarbans.  

·         Assessing the amount of carbon sequestration through mangrove forest of Sundarbans towards controlling global warming.

In order to achieve the above objectives, one research program has been envisaged. Planned procurement of the instruments as envisaged in the present project will essentially support two research programs as part of capacity building of the participating departments of the Calcutta University.

The first program will involve collection of representative soil and water samples from areas of Sundarbans having different vegetation assemblages and analysing the microbial diversity using structural and functional metagenomics. For this purpose one Pyrosequencer and Thermocycler or PCR machine have already been purchased. Pyrosequencer is the main instrument which provides detailed DNA sequence of the DNA samples. Pyrosequencer can also be used for performing both structural and functional metagenomics in order to understand microbial diversity. A Gel Documentation System has also been procured. Thermocycler has been used for the purpose of DNA amplification.

The program includes the following objectives:

• measurement of CO₂ sequestration and CH₄ emission from the mangrove forest and water,
• estimation of bacterial abundance (BA) and bacterial productivity (BP),
• measurement of inadvertent fertilization by nutrient flux (dissolved inorganic nitrogen), dissolved inorganic phosphate silicate from rivers
• measurement/estimation of residual flow of nutrients and organic carbon from the mangrove system to the coastal water

The other instrumental facilities that have been procured are:

·         Upright wide field research microscope with bright field, dark field, phase contrast and fluorescence with CCD camera and software

·         Total carbon analyzer

·         Liquid scintillation counter

·         Variable temperature programmable Incubator with Shaker system (BOD incubator)

·         Nitric oxide analyser

·         Fluorescence spectrometer with life time measurement

The University of Calcutta planned to execute the entire task in micro stages that are as noted as:

¨       Reconnaissance survey of the entire area, selection of field stations, gathering of basic knowledge about the area, recruitment of research personnel, procurement of instruments.

¨       Sample collection for bacterial culture and to undertake organic, pollutant and chemical analysis of coastal sediments.

¨       Metagenomic analysis and cataloguing of bacterial population.  Estimation of primary productivity of the ecosystem. Measurement of nutrient flux.

¨       Collation of data and Information, computational and bio-informatics study, model development.

Expected Outcome

Expected outcome of the project is cataloguing and describing the microbial diversity of Sundarban which is needed for the conservation and sustenance of this heritage site. The capacity building through this project will also construct an instrumental facility to support marine research. The third outcome is to create awareness among the new generation regarding the importance of coast and marine areas.

The project cost has been estimated at `5.6 crores out of which capital cost will be about `3.125 crores towards procurement of equipment and recurring cost will be about `2.475 crores.