Biofloc Production Research Articles

Effect of different biofloc system on water quality, biofloc composition and growth performance inLitopenaeus vannamei(Boone, 1931)

The experiment was conducted with three biofloc treatments and one control in triplicate in 500 L capacity indoor tanks. Biofloc tanks, filled with 350 L of water, were fed with sugarcane molasses (BFTS), tapioca flour (BFTT), wheat flour (BFTW) and clean water as control without biofloc and allowed to stand for 30 days. The postlarvae of Litopenaeus vannamei (Boone, 1931) with an Average body weight of 0.15 ± 0.02 g were stocked at the rate of 130 PL m−2 and cultured for a period of 60 days fed with pelleted feed at the rate of 1.5% of biomass. The total suspended solids (TSS) level was maintained at around 500 mg L−1 in BFT tanks. The addition of carbohydrate significantly reduced the total ammonia-N (TAN), nitrite-N and nitrate-N in water and it significantly increased the total heterotrophic bacteria (THB) population in the biofloc treatments. There was a significant difference in the final average body weight (8.49 ± 0.09 g) in the wheat flour treatment (BFTW) than those treatment and control group of the shrimp. Survival of the shrimps was not affected by the treatments and ranged between 82.02% and 90.3%. The proximate and chemical composition of biofloc and proximate composition of the shrimp was significantly different between the biofloc treatments and control. Tintinids, ciliates, copepods, cyanobacteria and nematodes were identified in all the biofloc treatments, nematodes being the most dominant group of organisms in the biofloc. It could be concluded that the use of wheat flour (BFTW) effectively enhanced the biofloc production and contributed towards better water quality which resulted in higher production of shrimp.

Performance of a temperate-zone channel catfish biofloc technology production system during winter

Channel catfish (Ictalurus punctatus) have been grown successfully in an outdoor biofloc technology production system. Outdoor biofloc production systems in the tropics are operated year-round, whereas the channel catfish studies were conducted only during the growing season and biofloc production tanks were harvested and idled for the winter. If an outdoor biofloc production system is to be adopted by farmers at temperate latitudes, then data gaps related to system and fish performance over the winter must be addressed. The present study was conducted to address these data gaps for channel catfish culture. Waters from a recently completed biofloc production experiment that contained low (153.3mg/L) and high (790.0mg/L) total suspended solids were retained for this study. Three 15.7-m3 tanks per water type each were stocked (8kg/m3) with market size channel catfish from that same study for a 152-day study from November to April. Mean chlorophyll a concentrations were similar in both treatments during the first 55 days, after which treatments diverged and chlorophyll a concentration increased linearly (P<0.001, R2=0.721) to a mean final concentration of 2251.7mg/m3 in the low solids treatment. Ammonia from ammonium chloride spikes (1.25–1.5mg TAN) added on three occasions during the experiment was biotransformed completely, putatively by algal uptake and nitrification. Ammonia biotransformation rate was linearly related to mean water temperature in the high solids (P<0.001, R2=0.920) and low solids (P=0.002, R2=0.761) treatments. Catfish survival through the winter was high (99.75%) in biofloc tanks and did not differ significantly between treatments. Net fish yield did not differ significantly between treatments. However, net fish yields were 1–4% less than initial fish biomasses. Water in the biofloc production tanks appeared to retain through the winter the ability to biotransform ammonia regardless of whether phytoplankton or suspended solids predominate and despite sustained input of ammonia-nitrogen. Having an active biofloc in the spring obviates the start-up time required to establish a new, fully functional biofloc and the associated TAN and nitrite spikes.

Sustainable Growth of Shrimp Aquaculture Through Biofloc Production as Alternative to Fishmeal in Shrimp Feeds

As capture fisheries are now fully exploited in Egypt, aquaculture is considered the only source for meeting the demand of seafood for rapidly growing populations in Egypt. To meet these demands for seafood, aquaculture has to grow fast and to be more intensive. Fishmeal sources from capture fisheries are fully exploited and thus become costly ingredient in fish and crustacean feed formulations. The present study evaluated biofloc technology as a sustainable alternative to fishmeal in the shrimp feeds using cheap carbon source for stimulation of the microbial biofloc growth, in addition to reduce protein content of the shrimp feeds. The shrimp were fed on three different diets (Control 45% CP, BF25.10 and BF30.10). The shrimp were cultured for 150 days. The water quality in biofloc-based pond was maintained with the promotion and development of biofloc through rice bran addition during the experiment. At the end of the experiment, the total yields of the shrimp in the two biofloc treatments were significantly higher than those of the shrimp in the control group (P < 0.05). The results indicated that promoting biofloc through carbohydrate addition in culture systems could enhance growth performance and water quality of cultured shrimp under the conditions of the present study. Feed conversion ratio (FCR) was significantly (P < 0.05) differed among treatments compared to control diet (1.51 ± 0.11; 1.66 ± 0.13 and 1.80 ± 0.10 for BF25.10; BF30.10 and control, respectively). There were significant differences (P < 0.05) in shrimp mean final weight between treatments and control diet (37.10 ± 2.22 g; 35.31 ± 1.52 g and 33.24 ± 2.17 g for BF25.10; BF30.10 and control, respectively). Mean survival (70 ± 8.30%; 66 ± 9.10% and 57 ± 11.00%, for BF30.10 ; BF25.10 and control, respectively. was significantly differed among treatments compared to control diet. The data suggests that substituting high-protein (Control 45% CP) with low-protein (BF25.10 and BF30.10) feed in a biofloc dominated system operated with minimal discharge may provide an alternative to improve shrimp farming technology, through improved water quality, cheaper (lower protein) feed and reduced environmental impact. The biochemical composition of the biofloc treatments did not vary significantly. Biofloc grown on BF25.10 had higher protein content (23 ± 7 % DW) than BF30.10 treatment (18 ± 5 %DW). The composition of the PUFAs in the biofloc showed that the treatment of biofloc with BF25.10 contained significantly more total n-3 PUFA and total n-6 PUFA than that with treatment of BF30.10. The results of the present study proofed that biofloc is a possible additional nutritious aquaculture feed for shrimp.

Sustainable Growth of Shrimp Aquaculture and Protection of Natural Fisheries Through Biofloc Production as Alternative to Fishmeal in Shrimp Feeds

As capture fisheries are now fully exploited in Egypt, aquaculture is considered the only source for meeting the demand of seafood for rapidly growing populations in Egypt. To meet these demands for seafood, aquaculture has to grow fast and to be more intensive. This expected growth in aquaculture require utilization of inputs mainly, sources for high quality seeds and fishmeal for production of feeds for cultured fish and crustacean. Fishmeal sources from cap-ture fisheries are fully exploited and thus become costly ingredient in fish and crustacean feeds formulation. There is a need to develop technology that will increase economic and environ-mental sustainability. The present study evaluated biofloc technology as a sustainable alterna-tive to fishmeal in the shrimp feeds. It based on using cheap carbon source for stimulation of the growth of the microbial biofloc in addition to reduce protein content of the feeds and in-crease carbohydrate content. This lower feed price without affecting shrimp growth. Also, shrimp are not efficient in the digestion of the carbohydrates, which will be released in the wa-ter in shrimp faeces and in turn stimulate biofloc production. The shrimp were fed diets with low fishmeal content had a slightly better growth and FCR. The biochemical composition of the biofloc treatments didn’t vary significantly. Bioflocs grown on 25.20 % CP + rice bran have a high protein content 20 ± 7 DW. Regarding the composition of the PUFAs in the bio-flocs, the bio-flocs with 25.20 % CP + Rice bran treatment contained significantly more LNA (18:3(n-3)) than that with 30.10 % CP+ Rice bran treatment and the opposite for LA (18:2(n-6)). In particular bio-flocs with 25.20 % CP + Rice bran treatment had a total n-6 PUFAs. The biofloc proofed to be a possible good additional nutritious aquaculture feed and accepted by the shrimp which play a crucial role in the use of bioflocs technology in aquaculture.

Performance of Pacific White Shrimp, Litopenaeus vannamei, Reared in Zero‐Exchange Tank Systems Exposed to Different Light Sources and Intensities

The development of biofloc production technology has generated significant commercial and research interest directed toward the inland culture of Pacific white shrimp, Litopenaeus vannamei. Most work to date has been conducted in greenhouses, where photoautotrophic organisms are significant contributors to system functionality. In more temperate locations, operations in insulated buildings would reduce heating costs. This experiment was designed to evaluate the effect of light on shrimp cultured in intensive biofloc systems. A 92‐d experiment was conducted in 3.8‐m3 tanks. There were five light treatments: (1) natural sunlight (SUN) as a control (midday: 718 lx); (2) one metal halide light (MHL) (1074 lx); (3) one fluorescent light (1FL) (214 lx); (4) two fluorescent lights (2FL) (428 lx); and (5) three fluorescent lights (3FL) (642 lx). Artificial light treatments operated on a 12:12 daily cycle. There were three replicate tanks per treatment and each was separated by black plastic to prevent light transmission between replicates. Each tank was stocked at 465 shrimp/m2 of tank bottom (initial mean weight = 0.4 g). Light treatment had a significant (P≤ 0.05) impact on average individual weight, survival, harvest yield (kg/m2), and feed conversion ratio (FCR). Harvest yield and survival among shrimp in the SUN, MHL, and 1FL treatments were not significantly different. However, there was an inverse linear relationship (P≤ 0.05; R2 = 0.76) between the number of fluorescent fixtures and survival, which was related to greater concentrations of filamentous bacteria as the intensity of fluorescent light increased, causing gill fouling. Natural light and MHL did not result in high concentrations of filamentous bacteria. These results indicate that natural light, metal halide lighting, and/or relatively low levels of fluorescent lighting are suitable for indoor production of Pacific white shrimp in biofloc systems. Light spectrum and intensity can affect bacterial community structure, which has a profound effect on shrimp survival and production.

Development of phytoplankton communities and common off-flavors in a biofloc technology system used for the culture of channel catfish (Ictalurus punctatus)

The use of biofloc technology production systems continues to increase in the aquaculture industry worldwide. Recent research demonstrated that outdoor biofloc systems can be used to produce high yields of channel catfish (Ictalurus punctatus). However, studies have not yet been performed to determine the development and composition of phytoplankton communities and related off-flavor problems in these biofloc production systems. In this study, water samples were collected biweekly from May to November and channel catfish samples were collected during harvest in November from nine 18.6m2 biofloc culture tanks. Water and fillet samples were analyzed for levels of the common off-flavor compounds geosmin and 2-methylisoborneol (MIB). The development and composition of phytoplankton communities in each culture tank was also monitored. In addition, water and biofloc samples were evaluated to assess the microbial sources of geosmin and MIB within the culture tanks. Phytoplankton (including algae and cyanobacteria attached to bioflocs) biomass, as determined by concentrations of chlorophyll a in the water, gradually increased in all tanks over time. Phytoplankton communities that developed in the culture tanks were dominated by fast-growing, unicellular and small colonial types of green algae (chlorophytes) and diatoms (bacillariophytes) and slower growing, small colonial types of cyanobacteria (cyanophytes). A positive correlation (p<0.05) between cumulative feed addition and chlorophyll a concentration was found. Although geosmin and MIB were present in the culture water of each tank during most of the study, levels were typically low and only one tank yielded catfish with geosmin and MIB in their flesh at levels high enough to be designated as off-flavor. A positive correlation (p<0.05) between cumulative feed addition and MIB concentrations in the water of culture tanks indicates a greater potential for MIB-related off-flavor problems at high feed application rates. The microbial sources responsible for production of geosmin and MIB in the culture tanks remain unknown.

Evaluation of Two Textiles with or without Polymer Addition for Dewatering Effluent from an Intensive Biofloc Production System

Intensive, recirculating aquaculture systems create concentrated wastes high in solid content. Geotextile has successfully dewatered aquaculture effluent; however, burlap, made from natural plant fiber, may provide similar filtering capabilities at a lower cost. The trial was designed as a 2 × 2 factorial to evaluate burlap bags and geotextile bags with or without polymer addition for dewatering Nile tilapia, Oreochromis niloticus, effluent from an intensive biofloc production system. There were no significant interactions (P > 0.05) between the main effects on the removal efficiency of total suspended solids (TSS) concentration. There were no significant differences (P > 0.05) in the main effect of textile; however, there were significant differences (P≤ 0.001) in the main effect of polymer on the removal efficiency of TSS concentration from effluent. Overall, TSS removal efficiency in textile-only treatments was 81%, whereas textile treatments in combination with polymer removed 98%. Partial budget analysis indicated that the cost per kilogram of solids (dry weight) removed from untreated effluent was US$1.52, 1.51, 0.16, and 0.14 for the geotextile with polymer (GP), geotextile without polymer (GNP), burlap with polymer (BP), and burlap without polymer (BNP) treatments, respectively. The BP could provide an effective treatment process for removing TSS in discharged effluent.

Optimization of biofloc production in Azospirillum brasilense (MTCC-125) and evaluation of its adherence with the roots of certain crops

The phenomenon of flocculation in Azospirillum brasilense (MTCC-125) was studied under different combinations of carbon and nitrogen sources. Fructose and Potassium nitrate at a pH of 6.4 in the cultural medium favour a higher bio-floc production. The biofloc was studied for root adhesion and its survival efficiency in the rhizoplane and rhizosphere of certain crops such as sorghum and sunflower under dryland condition. It has been demonstrated that the flocculated cultures of Azospirillum were found to have maximum adhesion to the root surface and higher survival rate in the rhizoplane and rhizosphere under different moisture stressed conditions as compared to the log phase cells of Azospirillum.