PERFORMANCE OF RECIRCULATING AQUACULTURE SYSTEM (RAS) IN SUPER-INTENSIVE WHITELEG SHRIMP (LITOPENAEUS VANNAMEI) CULTURED WITH DIFFERENT WATER SALINITY LEVELS

• Main Author: Rosefa, Syafira
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57862
• Institution: Institut Teknologi Bandung

Closed-system Aquaculture is an alternative technology for sustainable aquaculture. Recirculating Aquaculture Systems (RAS) applies technology where water is circulated continuously in a closed system through physical/mechanical, chemical and biological filtration processes so that the stability of water quality in the culture tanks can be maintained optimally during the culture period. This study aims to: (1) determine the performance of RAS on super-intensive whiteleg shrimp (Litopenaeus vannamei) cultured using different salinities; (2) determine the optimum salinity of whiteleg shrimp cultured in the RAS system; and (3) identify the microbial community profile in white shrimp cultured with the RAS system at different salinities. In this study, three separate units of the RAS system were used, each of which consisted of the following components: (1) a culture tank - a shrimp farm, (2) a settling tank - for settling and filtering coarse organic matter, (3) a protein skimmer - for capturing fine particulate and dissolved organic matter, (4) activated-carbon tanks for chemical contaminant filtration, and (5) biofilters for the nitrification process. The RAS was operated at three different salinities, namely 5 ppt (low), 20 ppt (medium) and 30 ppt (high). The salinity treatment was applied to the cultivation of Post-Larvae 25 shrimp fry (PL-25) during the 90 day culture period at a super-intensive stocking density of 500 PL/m3. Analysis of water quality parameters, shrimp biology, was carried out every week during the culture period. and Microbiological parameters to determine the profile of the microbial community were carried out at the beginning, middle and end of the culture period. This analysis was carried out by the Total Plate Count (TPC) test on shrimp samples and cultured water samples, then the analysis was carried out by 16S rRNA sequencing from isolates obtained in shrimp and water sample. The results showed that 5 ppt salinity treatment had the best performance based on productivity parameters with biomass production of 5.6±0.4 kg/m3 followed by 20 ppt (4.9±0.1 kg/m3) salinity treatment and 30 ppt salinity treatment (4.4±0.6 kg/m3) (p<0.05). The highest shrimp survival of 76.7±12.7% was found in the 30 ppt salinity treatment followed by the 20 ppt salinity (69.3±4.6 %) and 5 ppt (66.0±4.0%) salinity treatment (p >0.05). The lowest feed conversion ratio was found in the 30 ppt salinity treatment of 0.6±0.1 (p<0.05). Based on the culture water quality parameters, it was seen that all treatments had optimum concentrations of NH4 +, NO2 -, and NO3 - during the culture period. The results of the microbial community analysis showed that the use of the RAS system in shrimp culture had an impact on the stability of the community profile of heterotrophic bacteria in shrimp gut samples (102-104CFU/mg) and water (105-107 CFU/ml) and Vibrio bacteria in shrimp gut samples (101-103 CFU/mg) and water (103-105 CFU/ml) in the three salinity treatments. Based on the results of microbial abundance analysis using 16S rRNA sequencing analysis on shrimp and water samples, six pre-dominant bacterial isolates were obtained, namely Ruegeria arenilitoris, Stenotrophomonas maltophilia, Micrococcus sp., Demequina sediminicola, Pseudoalteromonas spongiae, and Shewanella algae which are potential probiotic candidate bacteria. The percentage of bacterial abundance in general showed a relatively stable microbial abundance during the cultivation period. The results of the analysis of the Shannon-Wienner Diversity Index which showed the highest microbial diversity was found in the 30 ppt salinity treatment. In general, shrimp cultivation carried out at high salinity showed increased microbial diversity during the culture period compared to low salinity. This is inversely proportional to the dominance index at high salinity which has decreased. It can be concluded that, RAS technology can be used for white shrimp cultivation at three different salinities and provides stable water quality and microbial community profiles during the culture period. Shrimp cultivation at low salinity can result in higher shrimp growth, while increasing salinity of culture water can increase the diversity of shrimp gut microbes which are thought to play a role in increasing shrimp survival by increasing Vibrio biocontrol in shrimp culture.