Gede Suantika

Advancement of rotifer culture and manipulation techniques in Europe

Abstract Since no artificial feed formulation for first feeding of marine larval fish has been developed yet, live prey feeding remains essential in commercial marine hatchery operations. Because cultured rotifers are relatively poor in eicosapentaenoic acid (EPA: 20:5n-3) and docosahexaenoic acid (DHA: 22:6n-3), it is essential and therefore common practice to enrich these live prey with emulsions of marine oils. The short-term exposure to oil emulsions results in lipid-encapsulated rotifers with high EPA and DHA levels. However, these rotifers are prone to fast losses of their gut content and show a distortion in their protein/lipid balance. Rather than submerging rotifers in oil emulsions, it is often preferred to use formulated culture diets when medium to low enrichment values are needed in live prey. The use of these diets contributes not only to the filling of the gut of the rotifers with nutrients, it generally creates a more stable entire body composition which is important especially when rotifers are not consumed immediately by the larvae. New culture techniques for rotifers, such as closed recirculation systems, are offering new possibilities for continuous supplies of high quality rotifers at 10 times higher densities than in batch cultures. The production increase in these systems is explained by the better water quality obtained by the introduction of protein skimmers, ozone treatment, and biological filtration. Although disinfection of rotifers remains a bottleneck, it has been observed that rotifer populations cultured at high densities are not prone to higher bacterial infestation. Also, the problem of unexplained mortalities in batch cultures seems to be partly solved by the introduction of recirculation systems or by bacterial management (introduction of probionts), which allow more reliable rotifer production.

High-density production of the rotifer Brachionus plicatilis in a recirculation system: consideration of water quality, zootechnical and nutritional aspects.

Rotifers were reared on the artificial diet culture Selco® in batch and recirculation conditions at different water exchange rates. The different rearing conditions resulted in considerable changes in water quality, which in their turn affected rotifer growth and food consumption. At a daily water exchange rate of 100%, no positive effect was obtained in rotifer growth compared to the batch rearing system, but the rotifer culture period could be prolonged by 1 week. By increasing the daily water exchange rate from 100 to 300% the maximum rotifer density could be significantly (P<0.05) increased from 1800 to 2500 individuals ml−1. At the highest recirculation rate (daily water exchange of 500%) the highest rotifer production (2800 individuals per milliter in 11 days) was obtained after adjustment of the feeding scheme. This adjustment was necessary to compensate for food losses in the recirculation system. The use of a modified culture Selco (CSH) could further improve the performance of the rotifers. Using this experimental diet, a rotifer density of 8000 individuals per milliter could be obtained in 8 days without rinsing and restocking during the production period. When the rotifer populations were kept below their maximal density by daily harvests the culture period could be extended to more than 1 month. During this period the cultures were not subjected to any water exchange or restocking except the replacement of the water to compensate for the daily harvested rotifers (±20% of the standing population). In general terms it can be stated that the use of a recirculation system has proved to reduce labour and maintenance cost while ensuring stable physico-chemical rearing conditions resulting in more reliable and healthy rotifer cultures.

Monitoring of the evolving diversity of the microbial community present in rotifer cultures

Abstract The genetic fingerprint of the microbiota in the culture water of two different rotifer culture systems (batch versus recirculation) was obtained by means of denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. The genetic profile of the bacterial community present in the culture water of a batch culture system changed daily due to shifts occurring at the level of the dominance of bands. By means of statistical tools, it was possible to distinguish three different periods during the development of the microbiota in the recirculation experiment, each corresponding to a typical period during the production of rotifers. Overall, it was obvious that the microbiota in such a recirculation system was less susceptible for variation relative to the microbiota in a batch system. However, some shifts in the genetic profile were observed when technical problems occurred resulting in a reduced water quality or performance of the biofilter. Characterisation of the microbial community present in the recirculation system indicated that the sequences of typical bands showed the highest level of identity to the sequences from the bacterial strain MMB-1 T (representing a species in the genus Marinomonas , Marinomonas mediterranea sp.), M. vaga and Pseudoalteromonas haloplanktis spp. tetraodonis strain IAM 14160 (98%).

Technical and economical feasibility of a rotifer recirculation system

Abstract A feasibility study was performed on the use of a recirculation system for the mass culturing of rotifers at industrial level. Rotifer culture systems with a culture volume of 750 l were operated at three different stocking densities (3000, 5000 and 7000 individuals ml−1) in a completely closed recirculation system. At all operating rotifer densities, a reliable production of 2.2 billion rotifers could be obtained on a daily basis during 3 weeks. Excellent water quality was maintained by the use of protein skimmers, the use of ozone and a submerged biofilter. The microbial counts remained stable during the whole culture period (106 CFU ml−1 on marine agar and 104 CFU ml−1 on TCBS after 15 and 23 days, respectively). No difference in HUFA and protein content were obtained between rotifers harvested from the recirculation system or from a conventional batch culture system. Compared to a commercial batch culture system, the use of a recirculation system can contribute to a 43% saving on the capital investment and the annual operation cost. By using this system, capital investment cost is considerably reduced by 46%. Savings are also made on labour cost (65%) and feed cost (21%) during a 1-year production. In general terms, it can be stated that by using a simple recirculation system, a cost-effective technology and a reliable rotifer culture can be obtained.

Oil productivity of the tropical marine diatom Thalassiosira sp.

To understand the potential of cultivating tropical marine diatom Thalassiosira sp. to produce biofuel, biodiesel product properties and growth characteristics of Thalassiosira sp. in three different media were investigated. After medium evaluation, significant Thalassiosira sp. cell growth was observed in both Walne and enriched seawater media, but not in plain seawater medium. The microalgae grew well in alkaline condition (pH range of 8.0-8.8). The average biomass density cultured in Walne and enriched seawater media on the 6th day was 4.36 and 2.50 g L(-1), respectively. Based on ESI-IT-MS spectra, the TAGs of algal oil were identified as POP, POO, and SOO, and the FAMEs as oleic acid methyl ester. The oil productivity of Thalassiosira sp. cultured in Walne and enriched seawater media were 150 and 290 μL L(-1) d(-1), respectively. The density and kinematic viscosity of Thalassiosira sp. biodiesel were 0.857 g mL(-1) and 1.151 mm(2) s(-1).

The Use of Indigenous Probiotic Halomonas aquamarina and Shewanella algae for White Shrimp (Litopenaeus vannamei Boone) Hatchery Productivity in Zero Water Discharge System

This research was aimed to improve the performance of white shrimp postlarvae culture through the application of indigeneous probiotic bacteria, Halomonas aquamarina and Shewanella algae in zero water discharge system. The research was conducted by following two consecutive steps: (1) pathogenicity test of both probiotic in white shrimp culture, and (2) probiotic effect test to water quality and vibriosis syndrome control. From the first step, the use of probiotics had no pathogenocity effect to shrimp PL since survival rate of 84-98% was documented. From step two, the application of both probiotic bacteria was able to inhibit the population growth of V. harveyi in which the highest survival rate of 93.94% obtained from H. aquamarina addition, followed by S. algae addition (92.12%), H. aquamarina: S. algae addition (90.60%), S. algae: V. harveyi addition (89.39%), H. aquamarina: S. algae: V. harveyi addition (87.87%), H. aquamarina: V. harveyi addition (87.57%), no addition of bacteria (84.84%) and V. harveyi addition (82.42%). There was no significantly different (p>0.05) among the treatments on all water quality parameters which were still in tolerance range of white shrimp PL culture (salinity 26-30 ppt; temperature 26-28°C; pH 7.5-8.5; DO 5.7-6.4 mgL-1; ammonia 0.1-0.5 mgL-1; nitrite 0.02-0.25 mgL-1; nitrate 5-40 mgL-1). In term of other biological parameter, the use of these probiotics was significantly affecting the weight increase of shrimps. Bacterial identification showed that there was a major similarity of microbial diversity found both in water and L.vannamei intestine. It could be concluded that the use of H. aquamarina and S. algae as indigene probiotics contributed to the increase of shrimp survival rate. However this effect was not clearly described by the effect of water quality parameters improvement and it most probably due to the inhibition activity of these two probiotics on V. harveyi.

Use of Zero Water Discharge Technology through the Application of Nitrifying Bacteria and Textile Vertical Substrate in Grow-Out Phase of Macrobrachium rosenbergii De Man

This study was conducted to develop a zero water discharge technology for Macrobrachium rosenbergii growth in order to solve the unpredictability of prawn production during grow-out phase.The system consists of three major compartments: (1) Prawn culture tank, (2) Trickling biofilter for nitrification process, and (3) Textile vertical substrate for prawn territory expansion. The trial was conducted in three diferent stages: (1) nitrifying bacteria of 105 Colony Forming Units.mL-1(CFU.mL-1) was inoculated into the culture 24 hours prior to juvenile stocking and every 10 days during culture period, (2) the culture was grouped into five treatments: 30 individuals.m2 (control), 40 individuals.m2, 50 individuals.m2, 60 individuals.m2, and 70 individuals.m2, and (3) measurements of biological, physicochemical, and microbiological culture parameters. Optimum culture performance was obtained in the culture with initial stocking density of 30 individuals.m-2 (control) with final metabolic body weight, length, specific growth rate (SGR), survival rate (SR), feed conversion rate (FCR) of (11.37 ± 4.92) g, (10.69 ± 1.45) cm, 2.569%.day-1, 78.3%, and 0.99, respectively. However, from an economic perspective, stocking with 70 individuals.m-2 (treatment IV) produced the highest total final biomass (975 g) and highest profit (Rp. 19.285 per kg) compared to the other treatments. Results indicate that use of the developed zero-water discharge rearing system with the application of nitrifying bacteria and textile vertical substrate can maintain good water quality to support a higher stocking density, better growth and larval survival rate and profit of prawn M. rosenbergii de Man grow-out culture.

Does zero-water discharged technology enhance culture performance of pacific white shrimp (Litopenaeus vannamei Boone.)?

Litopenaeus vannamei or white leg shrimp is an introduced shrimp which has successfully cultured in Indonesia. In Indonesia, L. vannamei is commonly cultured on outdoor/earthen pond that requires renewal of water, less control in term of water quality and disease and attributed to unpredictable yield production. Based on the existing culture condition, a system that enable to minimize water consumption, improve the hygiene of the culture and at the same time maintain a more stable yield production is urgent to be developed by using a zero water discharge system. The system consists of: (a) culture tank – to retain and culture the shrimp; (b) CaCO3 grained – buffering agent and substrate of nitrifying bacteria; (c) aeration line – to provide O2 and homogenize the culture; (d) ancho (feeding) – to control an appropriate feed; (e) nitrifying bacteria adding – to consume ammonium and nitrite then convert it to nitrate, and also control pathogen Vibrio sp.; (f) diatom microalgae (Chaetoceros gracilis) – to upt...

Application of Indoor Recirculation Aquaculture System for White Shrimp ( Litopenaeus vannamei ) Growout Super-Intensive Culture at Low Salinity Condition

The use of close aquaculture system including Recirculation Aquaculture System (RAS) has been implemented to allow a more stable water quality, good hygiene and efficient use of water resources in wide shrimp aquaculture production. This study aims to optimize shrimp stocking density and to evaluate microbial community profile in super-intensive culture of Pacific white shrimp (Litopenaeus vannamei) using RAS technology at low salinity. Before stocking, post larvae shrimp was gradually acclimatized from salinity level of 32 ppt to 5 ppt within 14 days. Different stocking density of 500 PL/m3, 750 PL/m3 and 1,000 PL/m3 were tested in four replicates. During 84 days grow out period, no differences in water quality parameters were observed. At the end of grow out period, significant differences were found in final body weight (14.87 ± 0.24 g, 13.09 ± 0.78 g, 11.32 ± 0.71 g), survival (70 ± 1.42%, 53.67 ± 4.16%, 44 ± 1.35%), specific growth rate (7.12%BW/day, 6.95% BW/day, 6.79% BW/day), and feed conversion ratio (1.32 ± 0.09, 1.45 ± 0.16, 2.05 ± 0.24) for the 500 PL/m3, 750 PL/m3, and 1,000 PL/m3 treatment group, respectively. However, similar total productivity of 5.20 kg/m3, 5.24 kg/m3, and 4.99 kg/m3 was observed for 500 PL/m3, 750 PL/m3, and 1,000 PL/m3 treatment group, respectively. The implementation of RAS can allow a stable community structure of culturable bacteria even at high shrimp density of up to 1,000 PL/m3, with the observed bacterial abundance of 1.28 × 103 to 5.28 × 104 CFU/mL and 9.49 × 104 to 2.27 × 106 CFU/mL in shrimp and culture water, respectively. It is suggested that the application of RAS at the optimal shrimp density of 500 PL/m3 allowed a high shrimp culture productivity of up to 5.20 kg/m3 within 84 days grow out period.