Organic Matter and Benthic Fauna Analysis in a Pond Based Multi Trophic Aquaculture System

Abstract

The study was carried out to evaluate the variation of soil parameter and benthos diversity in pond based IMTA (Integrated Multi Trophic Aquaculture) system. An experiment was conducted in the research ponds of Fisheries and Marine Resource Technology Discipline, Khulna University from December 2021 to May 2022. Samplings were done at fortnightly intervals. There were four treatments and one control, each of which had three replications. The experiment was designed by incorporating rohu, mola, snail, aquatic vegetable (kolmi) along with main crop prawn and tested in different treatments viz C-only prawn, T1-prawn+rohu, T2-prawn+rohu+mola, T3-prawn+rohu+mola+snail and 'I4-prawn+rohu+mola+snail+aquatic vegetable (kolmi) with specific stocking densities like prawn at 2/m2, rohu at 0.1/m2, mola at 2/m2, snail at 0.25/m2. Same feed was applied in all four treatments and the control. The soil quality parameters of the experimental ponds were analyzed. The highest mean pH value was found to be 8.02 (C), whereas the lowest soil mean pH value 7.88 was found in T3. The highest and the lowest mean electrical conductivity value were found to be 4.58 (T3) and 4.22 (TI), followed by organic matter 3.19 (T3) and 2.93 (T4), total nitrogen 0.18 (C) and 0.16 (T3, T4), phosphorus 10.38 (T3) and 8.53 (TI) respectively during the study. In total 9 species of benthos belonging to 4 genera were identified and among them, Melanoides was the most dominant genera. Highest quantity of species was recorded In T4 (M maculate=83.50±15.61, M granifera=56.50±8.71, M polymorpha=69.50±7.41, P. globosa=8.33±3.86, B. angularis=10.17±6.34, Indoplanorbis exustus=7.83±3.08) followed by TI (M tuberculate=47.33±13.25) and in T2 (B. javanica=16.17±6.52, P. polita=1O.50±0.50). The highest number of species of macrobenthos species was recorded in T4 and minimum number of species was recorded in control pond.