The Government of India, assisted by the United Nations Development Programme (UNDP) and the Food and Agriculture Organization of the United Nations (FAO), is engaged in the Intensification of Freshwater Fish Culture and Training Project (IND/75/031) whose main purpose is to strengthen central research, training and demonstration facilities, to train specialized staff and to formulate and implement research and demonstration programmes.
As part of the project operation, FAO assigned Dr Janos Olah as Consultant (Pond Microbiology) from 6 February to 5 April 1985 with the following terms of reference:
Under the supervision of the National Project Director:
to assist in investigations into the organic microbiological and viral properties of decomposing sediment on pond bottom and their role in the production process both in drainable and undrainble ponds
to assist in investigation into the biochemical transformation of autochthonous and allochtonous organic and inorganic nutrients to sediment fertility in drainable and undrainable ponds
to review the progress of research carried out on quantification of the basic production process both in water column and at the sediment water interface
to plan future research to determine production processes in drainable and undrainable ponds
The Freshwater Aquaculture Research and Training Centre (FARTC), Bhubaneswar, is involved in extensive research on increasing the survival and growth rates of fish in nursery, rearing and stocking ponds. By various environmental manipulations, nutrient addition as organic and inorganic fertilizers and provision of supplementary feeds, high fish production of 10 t ha-1 year-1 have been achieved. However, the basic architecture of the pond remains to be understood in terms of productivity and the inorganic, organic and microbial characteristics of water and sediment media. An understanding of the basic production and recycling processes is essential for formulating and implementing measures for an optimized fish production.
The author was based at FARTC, Bhubaneswar, India. He worked with a group of nine scientists comprising chemists, biologists and microbiologists, including Messrs V.R.P. Sinha, S. Ayyappan, C.S. Purushothaman, Radheyshyam, Dilip Kumar, D.K. Chatterjee, P.K. Saha, K.C. Pani and H.K. Muduli.He was in close touch with the ongoing research work and also had discussions on the problems of undrainable ponds with the National Project Director, Dr V.R.P. Sinha.
During the earlier consultancy, a comprehensive environmental monitoring model for the rural undrainable ponds had been evolved and studies initiated on 32 undrainable ponds in Orissa. Considering the fish yields in these allochthonously, organic-enriched ponds and their high production potentials, further investigations on the basic production processes were planned. Details of methodologies for quantification of the processes, results of the investigations carried out and certain measures for realizing the potential fish yields are described in the report.
The pond environmental studies were initiated in 1983, during the first term of consultancy at FARTC, India. A brief evaluation of the work carried out in the last two years is presented here.
Detailed chemical and microbial investigations on the fish ponds in FARTC, Bhubaneswar, have been carried out to assess the effect of bleaching powder that is applied as a toxicant. Four ponds with and without treatment were monitored for water and sediment microflora and the differences were significant.Further investigations are proposed.
Together with a detailed hydrobiological investigation of a perennial lake in Bangalore, monthly studies on fifteen bacterial groups involved in nutrient cycles in the water and sediment media, decomposition of macrophytes and organic substrates, diurnal oxygen and nutrient cycles, gas production at the pond bottom and related aspects were made. This accounts for the first attempt at understanding the productive potential of a lake using the above indices.
Diversified and broad-ranging studies into the production and decomposition aspects of aquatic ecosystems by microbiology laboratory, together with specific bacterial studies.
Detailed studies on the production and decomposition processes of undrainable rural ponds which are a particular type of system. Community structure including microbial communities, primary production and respiration (also sediment) organic decomposition and nutrient uptake, sediment water interactions, energy flow are to be covered.
Environmental monitoring of fish ponds with increased organic fertilization, with cowdung at 10 000, 20 000, 40 000, 60 000, 80 000 and 100 000 kg/ha/year and fish growth studies with different methods of applications.
Investigations on the macrophyte decomposition, detritus formation and nutrient recycling in different ecosystems and identification of trophic levels with accumulation of energy.
Nutrient diffusion studies and exchange processes between water and the sediment media in fish ponds.
Initiation of studies on nitrogen fixation, denitrification and other processes to obtain information on the protein metabolism of fish pond ecosystems.
Standardization of fish culture practices based on the knowledge of the basic processes contributing to production, for an effective utilization of natural fish food organisms abundant in tropical waters.
Seven methods were introduced and applied with sophisticated equipment and procedures. Descriptions of methods used are supplied with principles, necessary equipment, chemicals, procedures, calculations:
determination of nitrogen fixation in pond water
determination of nitrogen fixation in pond sediment
determination of ammonia and nitrate uptake in pond water with enzyme kinetics
determination of denitrification in lake water with the acetylene inhibition method
determination of denitrification in lake sediment with the acetylene inhibition method
determination of the actual diffusion of nutrients at the sediment water interface
determination of potential diffusion of nutrients at the sediment water interface
Five research aspects were covered comprising of field work, laboratory studies, data processing and evaluation.
primary production and related fish yields in fish ponds with varying management practices
community metabolism in tropical undrainable fish ponds
sediment oxygen consumption in tropical undrainable fish ponds
detritus associated respiration during macrophyte decomposition
introduction of daily manuring practice into composite fish culture technology and its environmental monitoring.
