Abstract

Evaluation of bagasse assisted biostimulation in coastal aquaculture through field and molecular approaches

Author(s): K.K.Krishnani, A.Nagavel, V.Kathiravan, K.Ponnusamy, H.G.Solanki, S.M.Pillai, G.Ponniah

A zero-water exchange system is an environmentally friendly alternative to conventional aquaculture for producing high-density shrimp. We present here the development and evaluation of bagasse biostimulation technology for maintaining lower ammonia and achieving higher shrimp production under field conditions. Total thirteen field trials were conducted in zero water exchange systems cultured with tiger shrimp Penaeus monodon. Results demonstrated up to 52% ammonia removal in the biostimulated culture ponds, due to a biofilmmode of growth of nitrifying consortia onto bagasse. The autotrophic ammonia oxidizing bacterial biofilm population was quantified using real-time PCR assay targeting ammonia monooxygenase (amoA) gene, which was found to be in the range of 104-105 and 105-106 amoA gene copies/g of the substrate based on the amount of aeration and duration of the treatment with bagassebiostimulator applied in the ponds. There was no significant difference in total plate counts of heterotrophic bacteria and Vibrio sp. in soil and water of control and the treatment ponds. Higher shrimp production from4-23% in Tamil Nadu and 23-28% in Gujarat was achieved due to periphyton formation onto bagasse serving as a natural feed for the shrimp. Bagassebiostimulation technology is advantageous due to its cost effectiveness and simple technique and can easily be adopted by aqua-farmers using locally available sugarcane bagasse thereby ensuring water remediation and good yield.