Studies on Optimum Carrying Capacities of Mariculture Systems by Modelling Trophic Interactions

David, Neetha Susan (2009) Studies on Optimum Carrying Capacities of Mariculture Systems by Modelling Trophic Interactions. Doctoral thesis, ICAR - Central Marine Fisheries Research Institute.

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    Abstract

    An attempt was made to construct trophic models of different aquaculture systems where shrimp was used as the key species of culture. The three different systems of culture viz., extensive system of aquaculture (where shrimp was cultured with crabs), modified extensive system (where shrimp and fish are stocked and fed with manufactured feed ) and polyculture system ( where shrimp was stocked along with different types of fish and mussel ) were modeled using the trophic modeling software ECOPATH. Two scenarios of each system i.e., initial (the day of stocking) and final (day of harvest) were created to know the ecological changes brought about by the aquaculture process. The different input requirements of the model were biomass, production per biomass, consumption per biomass, harvest details and diet compositions of all the organisms associated with the system. About 11 - 12 ecological groups were created in each system. On mass balancing ecological information of the species, ecosystem indices and flow indices were obtained. The results of the model give an overview of the resources found in the pond simultaneously and reveal the degree of trophic interactions. The ecotrophic efficiency (EE) of phytoplankton and detritus was very low in all the system showing that it is very sparsely utilized. Hence energy transfer from lower trophic level seemed to be very low. The cultured species had a high EE as they were completely harvested from the system. On comparing the initial and final model it was found that the final stages of the extensive system and polyculture system of culture was having better ecosystem stability while the modified extensive system was highly unstable. The relative ascendancy was high in modified extensive system indicating its unstable situation. Also the system overhead decreased showing a decrease in “strength in reserve”. The flow to detritus was found to increase in the modified extensive system where formulated feed was used. A hypothetical model was constructed by introducing mussels in the feed aquaculture system. On modeling it was found that the introduction of mussels could bring about better stability to the system as there was high variation in the ecosystem indices. Carrying capacity of the above modeled systems could be calculated and optimum stocking densities of the cultured species are also given.

    Item Type: Thesis (Doctoral)
    Uncontrolled Keywords: Optimum Carrying Capacities; Mariculture Systems; Trophic Modelling
    Subjects: Aquaculture > Farming/Culture
    Aquaculture > Mariculture
    Marine Fisheries > Trophic Modelling
    Divisions: CMFRI-Kochi > Marine Capture > Molluscan Fisheries
    Subject Area > CMFRI > CMFRI-Kochi > Marine Capture > Molluscan Fisheries
    CMFRI-Kochi > Marine Capture > Molluscan Fisheries
    Subject Area > CMFRI-Kochi > Marine Capture > Molluscan Fisheries
    Depositing User: Arun Surendran
    Date Deposited: 02 Feb 2019 06:04
    Last Modified: 02 Feb 2019 06:04
    URI: http://eprints.cmfri.org.in/id/eprint/13380

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