ROLE OF SEAWEED EXTRACT (Sargassum sp) ALONG WITH FERMENTED TRASH FISH BASED LIQUID FERTILIZER IN ENHANCING PLANKTON PRODUCTIVITY
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Date
2019
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Fisheries College and Research Institute, Thoothukudi, Tamil Nadu Dr. J. Jayalalithaa Fisheries University
Abstract
A study was conducted to utilize the drifted seaweeds available along the coastal region of Gulf of Mannar and trash fish waste from Thoothukudi landing centers to develop liquid based fertilizers for aquaculture applications. The dominant drifted brown seaweed, Sargassum spp., was used to prepare a Seaweed based Liquid Fertilizer (SLF) on an anaerobic fermentation for 8 weeks (Rama Rao, 1990). Trash fishes were collected and mixed with jaggery and fermented for 14 days to prepare fermented Trash Fish Fertilizer (TFF) (Vincent etal. 2014). The fermented based SLF and TFF contained micro and macronutrients including N, K, P, Ca, Mg and Zn content were analyzed once in 3 days using ICP-OES. The macro nutrients were increased its concentration from 16th day onwards and it was continued up to 60 days. The increased ranges of N, P and K were 10.71 ± 0.599 mg/l to 33.14 ± 0.602 mg/l, 0.074 ± 0.051 mg/l to 2.193 ± 0.025 mg/l and 20.80 ± 0.362 mg/l to 238.17 ± 1.503 mg/l respectively. Micronutrients viz., Ca, Mg and Zn were observed in the ranges of 1.162 ± 0.171 mg/l to 10.05 ± 0.0321 mg/l, 4.103 ± 1.124 mg/l to 41.59 ± 0.965t mg/l and 0.001 ± 0.000 mg/l to 0.006 ± 0.005 mg/l respectively up to 15th of fermentation. The nutrient concentration was increased from 17th day onwards and continued up to 60 days. The increased ranges of Ca, Mg and Zn were 8.603 ± 0.020 mg/l to 35.333 ± 0.338 mg/l, 11.11 ± 0.509 mg/l to 54.26 ± 1.510 mg/l and 0.006 ± 0.002 mg/l to 0.007 ± 0.005 mg/l respectively. The concentration of the macro and micro nutrients during the fermentation for TFF was analyzed once in two days. The initial concentration of macro and micro nutrients were ranged from N (0.788 ± 0.194 to 25.23 ± 0.315), P (1.915 ± 0.047 to 65.74 ± 8.84), K (11.22 ± 0.378 to 131.59 ± 52.06), Ca (2.106 ± 0.397 to 85.74 ± 2.083), Mg (5.143 ± 0.08 to 40.79 ± 1.124) and Zn (0.013 ± 0.003 to 0.161 ± 0.002). The physical characteristics such as pH, odour and colour for SLF and FTF were observed throughout fermentation period. Based on the results of the study, an experiment was conducted using marine microalgae such as Nannochloropsis oculata and Chlorella marina to study the effect of SLF and TFF (organic medium) and combination of both for the growth to compare with standard WM (inorganic medium). At 1.5 ml concentration for 100 ml of seawater, the maximum cell density of 16.1n x 106/ml of Nannochloropsis oculata was recorded on 13th day which retained for 2 days. In this study, maximum algal density of 11.79 n x 16 6 / ml of C.marina was reached on 15th day at 1.5 ml of extract in 100 ml of seawater. No observable growth was recorded for TFF and combination of SLF and TFF for C.marina and N. Oculata during the experimental period. Nutrient quality parameters viz., N, P and NO3 of the cultured algal medium were increased when compared to initial nutrient
level. The photosynthetic pigments such as chlorophyll a, b and c contents were estimated for algae cultured using SLF at 1.5 ml and fermented TFF for N.Oculata and C.marina. Chlorophyll concentration was slightly higher in algae cultured using WM than the algae cultured using SLF at 1.5 ml of extract.
The study reveals that SLF can enhance the growth of microalgae and nutrient uptake at the concentration of 1.5ml of the extract. Therefore, SLF could be used as an organic fertilizer to reduce the chemical fertilizer usage for sustainable aquaculture practices. Fermented extracts of SLF and TFF can be stored up to 6 months at room temperature.
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