Introduction, transmission and aggravation of malaria in desert ecosystem of Rajasthan, India

Background & objectives: Malaria is an important public health problem in northwestern desert partof Rajasthan. Since desert malaria is seasonal or unstable, there is a need to study its epidemiology inthe totality to address factors like how malaria is introduced into desert every year and what are desertspecifictransmission risk factors leading to epidemics?Methods: Twenty-six villages in irrigated, semi-irrigated and non-irrigated settings of the desert havebeen selected. Periodic investigations were undertaken in all the seasons from 2001 through 2002 todetermine causes of introduction of disease, the factors involved in its transmission and the epidemicrisk factors. Standard methods/procedures for mosquito collection, preservation and identification andfor parasitological studies were employed. Rainfall data were analysed and correlated.Results: Importation of malaria infection through individuals was the major cause of introduction ofdisease in all the 12 villages showing some initial load of infection. Areas having higher populationof cattle in relation to humans (human to cattle ratio of 1:25) had less transmission of disease (ratioof primary to secondary cases 1:3) as compared to relatively less cattle (human to cattle ratio 1:3)resulting into high transmission of disease with 1:47 ratio of primary to secondary cases. Introducedthrough migration, prospective transmission of malaria was observed as a resultant interaction ofdensity of three components namely malaria cases, vector density and cattle to human ratio. Rainfallmore than average when coupled with more cases of imported malaria leads to the eruption of malariaepidemics.Interpretation & conclusion: Importation of malaria cases was the major cause of seasonal introductionof malaria in the desert. This initial or primary parasitic load available in a village leads to aparticular transmission quantum depending upon the density of vectors, human and cattle populationat a particular time. Areas with more imported cases when coupled with profuse vector population leadto epidemic malaria situations in the desert

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Not AvailableThis study evaluated the effect of biofloc on water quality and growth performance of Etroplus suratensis for 161 days at ICAR-CCARI, Goa. It included two treatments T1 (wheat flour and formulated feed (2 per cent) of fish biomass) and T2 (wheat flour) and a control (formulated feed) with triplicate in 312 L capacity indoor cement tanks filled with 25 L of pond water and 275 L of tap water. The tanks were left for 15 days to make it favorable for the growth of microbes to develop the biofloc. The fingerlings of Pearlspot, Etroplus suratensis with an average body weight of 9.2 plus or minus 0.2 g were stocked at a rate of 50 number per tank and cultured for a period of 161 days. Specific growth rate (SGR) was recorded significantly (P less than 0.05) higher in T1 (1.06 plus or minus 0.19), followed by T2 (0.79 plus or minus 0.12) and control (0.46 plus or minus 0.09). Lower pH values were recorded in biofloc tanks may be attributed to the higher rate of nitrification and respiration by microbes. Besides, the addition of carbohydrate has significantly reduced the total ammonia nitrogen (TAN), and nitrate-nitrogen in water. The result of this study concluded that the use of wheat flour (carbohydrate source) along with formulated feed has effectively enhanced the biofloc production which contributed effectively in the maintenance of good water quality, resulting higher production of fish.Not Availabl

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Not AvailableThe dynamics of phytoplankton were studied corresponding to the environmental conditions in different aquaculture systems from coastal waters of Goa for a period of two years. A total of 45,39,51 and 24 species were identified from open water system (OWS) with mussel culture, semi-enclosed water systems (SEW) with mussel culture SEW with multispecies culture and OWS with multispecies culture, respectively. Diatoms and dinoflagellates were the major groups in all the culture systems. Nutrients, chlorophyll-a, phytoplankton biomass and diversity were significantly higher in semi-enclosed systems. This observations in semi-enclosed systems is inferred as a reaction to driving forces like polymixis, water-level changes and nutrient loading due to less flow rate in the system.Not Availabl

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Not AvailableA study was conducted for ecological and economic evaluation of four different aquaculture systems in coastal waters of Goa during 2013 to 2015; two semi-enclosed water systems and two open water systems. Economics of all the systems with break-even analysis has been carried out to compute the cost structure of different culture systems. End results revealed that the highest rate of return and lowest payback period were from SEWMS. Benefit cost ratio and rate of return were highest and payback period was found to be shortest for SEWMS. Thus, multi-species culture in semi-enclosed coastal waters was found to be profitable, economically efficient and productive system compared to monospecies culture. Considering all this, an ecological model was constructed for SEWMS and simulated the impacts of multispecies aquaculture at various scales in this ecosystem. An optimal ecologically sustainable scenario was established for a period of ten years. The work concludes that there is enough scope for developing the multi-species aquaculture practices in unutilised semi-enclosed coastal waters of Goa as a secondary livelihood option by giving adequate technical support to the farmers.Not Availabl

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Not AvailableThe objective of this study was to carry out the economic evaluation of different aquaculture systems in coastal waters of Goa. Break-even analysis was used to compute the economic viability of different culture systems. A survey was also conducted to study the perception of farmers on different aquaculture technologies introduced in coastal waters. Among the four aquaculture systems studied, the semi-enclosed multi-species culture system was the most productive. The highest benefit-cost ratio and rate of return and shortest payback period were observed for the semi-enclosed water system with multi-species culture. Thus, the multi-species culture was found more economically viable compared to the single-species system under similar environmental conditions. Moreover, for the semi-enclosed system, the productivity and survival of species were comparatively higher due to the control of water flow through sluice gates. Goa is rich in semi-enclosed water bodies, which have a history of being used for shrimp farming, but these systems can be utilized for multi-species aquaculture. Perception of farmers on the dissemination of culture techniques revealed that adequate technical support increases their confidence level. This paper posits that there is sufficient scope and feasibility for developing multi-species aquaculture practices in unutilised semi-enclosed coastal areas of Goa by giving adequate technical support to the farmers.Not Availabl

Variations in phytoplankton assemblages in different aquaculture systems in coastal waters of Goa

35-45The dynamics of phytoplankton were studied corresponding to the environmental conditions in different aquaculture systems from coastal waters of Goa for a period of two years. A total of 45, 39, 51 and 24 species were identified from open water system (OWS) with mussel culture, semi-enclosed water system (SEW) with mussel culture, SEW with multispecies culture and OWS with multispecies culture, respectively. Diatoms and dinoflagellates were the major groups in all the culture systems. Nutrients, chlorophyll-a, phytoplankton biomass and diversity were significantly higher in semi-enclosed systems. This observation in semi-enclosed systems is inferred as a reaction to driving forces like polymixis, water-level changes and nutrient loading due to less flow rate in the system