不同盐度对生物絮团、对虾生长以及酶活性的影响

在不同盐度条件下进行凡纳滨对虾的生物絮团养殖试验,研究盐度对生物絮团养殖水质和对虾生长及其酶活性的影响。试验设5个盐度梯度(10、15、20、25、30),生物絮团初始量为20 mL/L,对虾密度为500尾/m^3,试验周期30 d。试验结果显示,15盐度组与20盐度组的对虾体质量增长率最大,达70.73%,10盐度组的体质量增长率最小,达50.24%。盐度越高生物絮团生长越快,30盐度组17 d生物絮团沉降量达200 mL/L,之后逐渐降至43 mL/L,其他组呈相同变化趋势。试验过程中水体总碱度与pH持续降低,但不同组间差异不显著(P>0.05)。盐度越高氨氮累积越快,30盐度组在第6 d达到最大质量浓度8.62 mg/L,之后降至0 mg/L,其他组呈相同趋势变化。盐度越低亚硝态氮累积越快,10盐度组在第6 d达到最大质量浓度9.18 mg/L,之后降至0 mg/L,其他组呈相同趋势变化。硝态氮在不同盐度中呈前期上升的趋势,第16 d之后开始缓慢下降。15盐度组的淀粉酶活性显著高于其他组(P<0.05),其他各组之间无显著差异(P>0.05)。脂肪酶在25盐度组活性最高,盐度升高或者降低酶活性均降低。在10、15、20盐度组中,超氧化物歧化酶、碱性磷酸酶、酸性磷酸酶活性均维持在较高水平,在相同盐度下,肌肉酶活性低于肝胰脏。     

Effect of different diets on growth and digestive enzyme activity in Litopenaeus vannamei (Boone, 1931) early post-larvae

Growth rate, soluble-protein content and digestive-enzyme activities were studied in Litopenaeus vannamei (Boone, 1931) early post-larvae under six feeding regimens, which included combinations of freshly hatched Artemia nauplii, an artificial diet and algae. Growth (0.11 mg DW day⁻¹) and soluble-protein content (61.8 μg protein larvae⁻¹ at PL₁₀) of post-larvae fed mixed diets were significantly higher (P < 0.05). An artificial diet used alone or co-fed with algae caused the lowest growth (0.03–0.05 mg DW day⁻¹) and soluble-protein content (13.7–15.5 μg protein larvae⁻¹ at PL₁₀). Trypsin-like activity was higher (up to 10 times) in post-larvae fed Artemia nauplii and an artificial diet alone or plus algae. The artificial diet stimulated chymotrypsin activity, apparently in response to squid meal present in this diet. Amylase activity increased when post-larvae were fed the artificial diet. This was apparently related more to the origin of the starch than to the total carbohydrate level of the diet. No obvious relationship was found between enzyme activity and growth in any feed combination. Based on growth and soluble-protein content, we determined that partial substitution (50%) of Artemia nauplii by artificial diet and the use of algae co-fed beyond the first post-larval stage benefits growth and the nutritional state of L. vannamei post-larvae.     

投喂频率对凡纳滨对虾生长和水质的影响

研究了不同投喂频率(1,2,3,4和5次·d-1)对凡纳滨对虾生长、存活率和水质的影响。试验在室内2m3的圆形水泥池(d=1.6m)中进行,采用全封闭养殖模式,凡纳滨对虾(初始重量为0.24g)养殖密度为50尾·m-3,投喂人工配合饲料(粗蛋白含量为42.98%)。通过7周的试验,结果表明,投喂频率为1～4次·d-1时,随着投喂频率的增加,对虾增重率显著增加;投喂频率由4次·d-1增加到5次·d-1时,对虾增重率略有增加,但差异不显著。凡纳滨对虾的成活率在1次·d-1时最低,2次·d-1时最高,2～5次·d-1时随着投喂频率的增加而降低(投喂频率为1和2次·d-1之间、3和4次·d-1之间差异显著)。投喂频率为3次·d-1时饲料系数最低,蛋白质效率最高。随着投喂频率1～3次·d-1增加,饲料系数逐渐显著降低,蛋白质效率显著递增;而投喂频率从3～5次·d-1增加时,饲料系数增大,蛋白质效率逐渐下降(3和4次·d-1差异显著;4和5次·d-1之间差异不显著)。投喂频率对水环境中的pH值、H2S含量、COD、盐度等水质指标没有显著影响;在养殖后期水环境中投喂频率3～5次·d-1的NH 4和NO-2浓度较投喂频率1～2次·d-1时高。     

Effect of plant protein concentrates on nutrition physiology of Litopenaeus vannamei (Boone, 1883) juveniles

This study was designed to test the effect of soy protein (SPC), wheat gluten (WHG) and potato protein (PPC), in vitro and in vivo digestibility of protein and energy in the juveniles Litopeneaus vannamei. A completely random design was used with nine 400‐L tanks (with three repetitions by treatment). Ten respirometric chambers (500 mL) were used for energy distribution. In vitro digestibility for SPC (8.8%) was higher than for PPC (5.8%) and for WHG (4.3%, P < 0.05). Diets’ degree of hydrolysis ranged between 0.75% and 1.2%, with lowest value in potato protein concentrate diet (0.75 ± 0.09%, P < 0.05). No significant differences were obtained in apparent digestibility coefficient (ADC) for protein (63.4–74.1%). ADC for amino acids ranged between 80% and 90%. Daily growth coefficient ranged from 0.86% to 1.1% day⁻¹, being the best in soybean protein concentrate diet (SPCd) (P < 0.05). Significant differences on heat increment were observed (P < 0.05); highest value was in wheat gluten diet (1.0 ± 0.1 kJ shrimp day⁻¹) that coincided with a peak of trypsin specific activity (16.5 ± 3.7 mU mg protein⁻¹). Highest retained energy for growth was observed in shrimp fed SPCd (0.7 ± 0.03 kJ day⁻¹, P < 0.05). Muscle collagen content presented a minimum of bands with SPCd, whereas shrimp post‐mortem collagenase activity was not affected by any of the three diets (P > 0.05).     

Quantitative dietary threonine requirement of juvenile Pacific white shrimp, Litopenaeus vannamei (Boone) reared in low-salinity water

An 8-week feeding trial was conducted to determine the threonine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low-salinity water (0.50–1.50 g L⁻¹). Diets 1–6 were formulated to contain 360 g kg⁻¹ crude protein with fish meal, wheat gluten and pre-coated crystalline amino acids with six graded levels of l -threonine (9.9–19.0 g kg⁻¹ dry diet). Diet 7, which was served as a reference, contained only intact proteins (fish meal and wheat gluten). Each diet was randomly assigned to triplicate groups of 30 shrimps (0.48±0.01 g), each four times daily. Shrimps fed the reference diet had similar growth performance and feed utilization efficiency compared with shrimps fed the diets containing 13.3 g kg⁻¹ or higher threonine. Maximum specific growth rate (SGR) and protein efficiency ratio were obtained at 14.6 g kg⁻¹ dietary threonine, and increasing threonine beyond this level did not result in a better performance. Body compositions, triacyglycerol and total protein concentrations in haemolymph were significantly affected by the threonine level; however, the threonine contents in muscle, aspartate aminotransferase and alanine aminotransferase activities in haemolymph were not influenced by the dietary threonine levels. Broken-line regression analysis on SGR indicated that optimal dietary threonine requirement for L. vannamei was 13.6 g kg⁻¹ dry diet (37.8 g kg⁻¹ dietary protein).     

Effect of Low Salinity on Growth and Survival of Postlarvae and Juvenile Litopenaeus vannamei

The effect of low salinity on survival and growth of the Pacific white shrimp Litopenaeus vannamei was examined in the laboratory due to the interest of raising shrimp inland at low salinities. In three separate experiments, individual L. vannamei postlarvae (∼ 0.1 g) were cultured at salinities of either 0.5, 1, 1.5, 2, or 3 ppt ( N = 5 or 10/treatment) for 18 to 40 d at 30 C in individual 360-mL containers. In each experiment controls of 0 and 30 ppt were run. There was no postlarval survival at salinities < 2 ppt. Survival was significantly different ( P < 0.01) at 2 ppt (20%) compared to 30 ppt (80%). Growth was also significantly different ( P < 0.01) at 2 and 3 ppt compared to 30 ppt (416%, 475%, and 670%, respectively). A fourth experiment compared juveniles (∼ 8 g) and postlarvae (∼ 0.05 and 0.35 g). Shrimp were cultured at salinities of 0, 2, 4, and 30 ppt for 40 d at 25 C, in individual 360-mL and 6-L containers ( N = 7/treatment). There was no postlarval survival at < 2 ppt. Postlarval survival at 4 ppt (86%) was not significantly different (P > 0.05) from 30 ppt (100%). Juveniles exhibited better survival at lower salinities (100% at 2 ppt) than 0.05 and 0.35 g postlarvae (29% and 14% respectively, at 2 ppt). The effects of salinity on growth varied with sizdage. Final growth of 0.05 g postlarvae at 2 ppt (693%) was significantly less ( P < 0.01) than at 4 ppt (1085%) and 30 ppt (1064%). Growth of 0.35 g postlarvae was significantly less ( P < 0.01) for 4 ppt (175%) than for 30 ppt (264%). There was no growth data for juveniles (8 g). It appears from these experiments that the culture of L. vannamei poses risks when performed in salinities less than 2 ppt.     

Biotic communities and feeding habits of Litopenaeus vannamei (Boone 1931) and Litopenaeus stylirostris (Stimpson 1974) in monoculture and polyculture semi-intensive ponds

Zooplankton, macrozoobenthos and feeding habits of Litopenaeus stylirostris and L. vannamei in monoculture and polyculture semi‐intensive experimental ponds were evaluated. Zooplankton was more abundant in monoculture of L. stylirostris (1002±670 organisms (org.) L^?1) than in monoculture of L. vannamei (470±37 org. L^?1), and polyculture (321±188 org. L^?1). The main zooplanktonic groups were polychaeta larvae, nauplii, copepods and polychaeta. Macrozoobenthos was more abundant in polyculture (6898±11 137 org. m^?2) compared with monoculture of L. stylirostris (3201±350 org. m^?2) and L. vannamei (2384±3752 org. m^?2). The main benthic groups were copepods, polychaeta, ostracods, nematodes and insects. Differences in feeding habits were found between species and regimes. Litopenaeus vannamei showed to be a more voracious species and fed mostly on organic detritus and benthos in both culture regimes. Litopenaeus stylirostris had a more restricted sources of feed in the ponds. The major component in the stomach content of both species was detritus. Macroalgae, sand, exuvia, formulated feed, prey and microalgae were minor components for both species (<7%). Ingestion of formulated feed was <4% for L. stylirostris and was not detected for L. vannamei. The stomach repletion rates were larger for L. vannamei (55.6% and 48.8%) than for L. stylirostris (43.75% and 44.89%). Litopenaeus stylirostris grew better in polyculture (10.3±3.4 g) that in monoculture (9.0±3.8 g). Litopenaeus vannamei grew better in monoculture (16.1±4.8 g) than in polyculture (13.4±4.5 g). For both species, feed conversion ratio was lower in polyculture.     

饲料中添加凹土对凡纳滨对虾存活和生长的影响

研究了饲料中添加凹土（０．０％、０．５％、１．０％、２．０％、４．０％和８．０％）对凡纳滨对虾（１．０４～１．０６ｇ）存活和生长的影响。实验在淮海工学院江苏省海洋生物技术重点建设实验室进行,凡纳滨对虾（Ｌｉｔｏｐｅｎａｅｕｓｖａｎｎａｍｅｉ）幼虾购自海南某育苗场;实验采用单因子６水平设计,每个水族箱放养１０尾对虾,每个水平设３个重复。实验前停食２４ｈ,称其初始体重。日投饵２次,过量投饵;投饵２．５ｈ后从每个水族箱收集残饵、粪便和虾壳。实验周期３０ｄ。所得数据用单因素方差分析和Ｔｕｒｋｅｙ′ｓ多重比较进行处理。结果表明,饲料中添加凹土显著地影响对虾的特定生长率,而对存活率、摄食量、饲料系数和吸收效率的影响不显著;在２．０％凹土水平,凡纳滨对虾的特定生长率显著高于０．０％凹土水平,但与其它处理差异不显著;总的看来,２．０％凹土添加组对虾的饲料系数低于其它处理,而摄食量高于其它处理。     

盐度对菲律宾蛤仔浮游幼体存活和生长的影响

研究结果表明:菲律宾蛤仔受精卵在26℃水温下的最适孵化盐度为23 8～34 8,孵化率平均在80%以上;盐度38 3和21 2组,对受精卵的孵化有一定负面影响,孵化率为30%～60%;盐度低于15 9,受精卵基本上不能孵化;盐度29 5为幼体生长的最适盐度,8d可生长成下潜幼体,平均日生长16μm,成活率90%,盐度高于或低于29 5,其幼体的存活和生长都受到很大影响。     

Growth and performance of the whiteleg shrimp Penaeus vannamei (Boone) cultured in low‐salinity water with different stocking densities and acclimation times

We evaluated the performance of whiteleg shrimp Penaeus vannamei (Boone, 1931) in response to different stocking densities and acclimation periods. Shrimp postlarvae were acclimated from seawater (30 g L^?1) to low‐salinity well water (<1.0 g L^?1) at a constant hourly reduction rate of 40, 60, 80 and 100 h. After acclimation to low‐salinity well water, postlarvae from each acclimation time treatment were stocked in three replicate tanks at densities of 50, 100, 150 or 200 shrimps m^?2 for 12 weeks of growth. Salinity averaged <1.0 g L^?1 for each growth study. The different treatments resulted in significant differences in both the final body weight and the survival rate (SR). Shrimp acclimated for 100 h showed substantially improved survival (83%) relative to shrimp acclimated for shorter periods. Shrimp yields for all cultured periods ranged from 0.32 kg m^?2 in tanks stocked at 50 m^?2 to 1.14 kg m^?2 in tanks stocked at 200 m^?2. We conclude that whiteleg shrimp can be successfully grown in low‐salinity well water, and that the growth, production output and SRs are significantly higher when shrimp are acclimated for longer periods.     

Water quality,production parameters and nutritional condition of Litopenaeus vannamei (Boone, 1931) grown intensively in zero water exchange mesocosms with artificial substrates

The effect of artificial substrates on the water quality, production parameters and nutritional condition was assessed in experimental intensive cultures of Litopenaeus vannamei grown in mesocosm units with zero water exchange. The initial stocking densities in triplicate 1000 L tanks were 600 and 800 g of juvenile shrimp (2.7 g) per unit, with (W) and without (WO) artificial substrates. There were no significant differences between the water quality parameters of the four treatments. In the tanks with the lower stocking biomass, the best survival (96.7% vs. 87.0%), growth rate (1.69 vs. 1.35 g week⁻¹), final biomass (1969.6 vs. 1516.0 g m³) and feed conversion ratio (1.30 vs. 1.90) were obtained with artificial substrates. Similar results were observed for the higher stocking biomass (90.9% vs. 74.5%, 1.50 vs. 1.13 g week⁻¹, 2221.6 vs. 1560.8 g m³, and 1.50 vs. 2.60 respectively). The nutritional condition of shrimp was improved using artificial substrates. The protein content in muscle was higher (21.6% and 20.4%) in ponds with substrates as compared with the control (21.2% and 15.9%).     

饲料中添加不同类型核苷酸对凡纳滨对虾生长性能的影响

以1种对照饲料和3种分别添加200mg/kg鸟苷酸（5′-GMP）、腺苷酸（5′-AMP）和尿苷酸（5′-UMP）的试验饲料饲养平均体重为1.04±0.02g的凡纳滨对虾8周,研究不同类型核苷酸对凡纳滨对虾生长性能及体成分组成的影响。试验结果显示,四组试验虾的增重率组间差异不显著（P〉0.05）;AMP组的存活率显著高于UMP组（P〈0.05）,各添加核苷酸组与对照组之间无显著差异;各组的饲料系数差异不显著（P〉0.05）;各组虾全虾的水分、粗蛋白、粗脂肪及灰分含量均没有显著差异,其中添加核苷酸各组的粗蛋白及粗脂肪含量均高于对照组。     

Effect of salinity on natural community and production of Litopenaeus vannamei (Boone), within experimental zero-water exchange culture systems

Recent efforts have been made to culture marine shrimp in systems operating under low or zero‐water exchange and with decreased water salinity. The aim of this study was to investigate the impact of various salinity levels on qualitative and quantitative characteristics of the natural community and, more particularly, ciliated protozoa, and compare this information with shrimp growth and survival. Tanks with 9‰ salinity were characterized by a higher pH, but also by a significantly higher concentration of chlorophyll a (Chl a) per weight of suspended matter (1.93 ± 0.72 µg Chl a/mg TSS) than tanks with 18‰ (1.29 ± 0.68 µg Chl a/mg TSS) or 36‰ (1.37 ± 0.61 µg Chl a/mg TSS) salinity. Concentrations of ciliates (max 6000 cells mL^?1) showed considerable fluctuations over the sampling period, reflecting the impact of water salinity, dynamic interactions between ciliates and their diverse roles within the shrimp production system. There was no significant difference between survival rates of shrimp reared at 9‰, 18‰ or 36‰, but decreasing salinity from 36‰ to 9‰ led to a significant decrease in final shrimp body weight (from 13.40 ± 0.26 g to 10.23 ± 2.72 g). Future work should address the potential of ciliates as an indicator of aquaculture water quality, as is currently being done in the wastewater industry, and the contribution of ciliates as food sources.     

Activity pattern of the marine shrimp Litopenaeus vannamei (Boone 1931) in laboratory as a function of different feeding frequencies

Management practices on most Brazilian shrimp farms have resulted in high expenses for producers and damage to the environment. Applied ethology could provide information on the pattern of shrimp activity, enabling more efficient feeding frequencies. Behavioural activities of the shrimp Litopenaeus vannamei were recorded during different feeding frequencies. The shrimp were kept in aquariums on a 12:12 h light/dark cycle. They were fed commercial ration three (at 6:00, 12:00 and 18:00 hours), four (at 6:00, 10:00, 14:00 and 18:00 hours) or seven times per day (at 6:00. 8:00, 10:00, 12:00, 14:00, 16:00 and 18:00 hours). We observed animals at 15 min^?1 aquarium^?1 time periods, recording feeding, substrate exploration, swimming and inactivity. Feeding and exploration were the highest for shrimp fed three times per day, swimming was greatest when animals received four feedings, whereas inactivity was higher for shrimp fed seven times per day. There was greater food ingestion between 12:00 and 14:00 hours for animals fed three and four times per day, whereas swimming was high mainly at 18:00 hours for shrimp fed three and seven times per day. The results indicate higher forage‐related activities (exploration/ingestion) when feed was offered three or four times, suggesting optimization in the pattern of shrimp activities based on these feeding frequencies.     

Well-defined multispecies probiotic and enzyme combination outperforms traditional fermented probiotic applications in an intensive Pacific white shrimp,Litopenaeus vannamei (Boone, 1931), culture system

A series of treatments were designed to evaluate the efficacy of feeding commercial multispecies probiotics feeding with enzymes and fermentation process on the growth parameters and culture environment of Pacific white shrimp, Litopenaeus vannamei (Boone, 1931), in an intensive culture system. Commercial multispecies probiotics and enzymes (PEs) were continuously applied in three different doses, namely (i) 0.2, (ii) 0.4, and (iii) 0.6 mg L⁻¹ and designated as 0.2, 0.4, and 0.6 PE during the first 30 days of intensive culture of Pacific white shrimp, L. vannamei (Boone, 1931). The probiotics were continually applied every alternate day, while the enzymes were added every sixth day throughout the trial period. The PE dose for all treated tanks was increased by 0.2 ppm after 30 days of culture and another 0.2 ppm after day 60. Meanwhile, fermentation technique, which has become the common method applied in Indonesia in the control treatment, was added on the same day with the PE group with increasing dosage, following the same trend with the 0.6 PE group. Results showed that the group receiving 0.6 PE showed higher final biomass, higher mean weight, and protein retention efficiency as well as a lower feed conversion ratio compared with the control treatment. Abundance of Vibrio spp. remained below 10³ cfu mL⁻¹ throughout the trial. Water quality indicators TAN, NO₂ N and NO₃ N peaked in weeks 3–5 and then declined after that until the end of the culture period in all tanks. This decline was significantly faster in PE-treated tanks. Multispecies PEs have potential applications in controlling Vibrio spp., maintaining proper water quality condition, and enhancing the growth of shrimp in intensive culture system.     

Digestive enzyme activity and food ingesta in juvenile shrimp Litopenaeus vannamei (Boone, 1931) as a function of body weight

A study was conducted to evaluate variations of digestive enzyme activities in Litopenaeus vannamei (Boone) reared in commercial ponds under semi‐intensive conditions. Shrimp were collected at each body weight increase of 2 g. As the shrimp grew (2–12 g), significant increases in the activities of lipase and chymotrypsin were observed. The total protease activity decreased from 6 g onwards. Trypsin activity showed a peak at 6 g and amylase activity increased two‐fold after 2 g. Additionally, the stomach contents were analysed microscopically for shrimp between 2 and 10 g. Plant matter contributed above 30% of the total stomach content in 6‐, 8‐ and 10‐g shrimp. Detritus represented 58% and 62% of the total stomach content in 2‐ and 4‐g shrimp, respectively, decreasing to 33–43% at greater shrimp weights. Artificial feed showed a maximum contribution of 20% in 6‐g shrimp. The present results show changes in the enzyme activity after the shrimp reach 6 g in body weight, evidenced by a decrease in total protease and an increase in lipase and amylase activities. The amylase/protease ratio was 2.6 in 2‐g shrimp and increased steadily to 9.6 in 12‐g shrimp. These findings suggest an adaptation of the enzymatic activity to diets with lower protein content as body weight increases, and may be related to the variation of the different items found in the stomach.     

低盐度条件下的凡纳滨对虾幼虾亮氨酸营养需求

为了探讨低盐度(0.6～0.8 g/L)条件下初始体质量为(0.38±0.004)g的凡纳滨对虾(Litopenaeus vannamei)幼虾的亮氨酸需求量,以鱼粉、花生麸和L-晶体氨基酸为蛋白源配制含粗蛋白400 g/kg的6种等氮饲料,标记为L7～L12组,各组亮氨酸水平分别为15.95、17.95、19.95、21.95、23.95和25.95 g/kg(饲料干物质).每组3个重复,每个重复30尾虾,进行56 d生长实验.结果表明,凡纳滨对虾幼虾的增重率随饲料亮氨酸水平的升高而升高,当亮氨酸水平达到23.95 g/kg(L11组)时,增重率达到最高值(1143.11±36.40)％,显著高于L7组(P＜0.05);亮氨酸水平继续提高,增重率变化不显著(P＞0.05).幼虾的蛋白质效率、全虾体蛋白沉积率和血淋巴总蛋白随着饲料亮氨酸水平的升高呈现升高趋势,最高值出现在L11组,并显著高于L7组(P＜0.05).各实验组饵料系数、血淋巴谷丙转氨酶、谷草转氨酶活性和尿素氮含量则呈现降低的趋势,最低值出现在L11组,且显著低于L7组(P＜0.05).以增重率为指标,根据折线模型可知,低盐度条件下凡纳滨对虾幼虾的亮氨酸最适需要量为24.80 g/kg饲料,即61.99 g/kg饲料蛋白.     

Effect of different biofloc system on water quality,biofloc composition and growth performance in Litopenaeus 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 (BFT_S), tapioca flour (BFT_T), wheat flour (BFT_W) 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 (BFT_W) 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 (BFT_W) effectively enhanced the biofloc production and contributed towards better water quality which resulted in higher production of shrimp.     

Soybean molasses as an organic carbon source in the farming of Litopenaeus vannamei (Boone, 1931) in a biofloc system

Soybean molasses was evaluated as a partial replacement for sugarcane molasses as a carbon source for biofloc development in the superintensive culture of Pacific white shrimp (Litopenaeus vannamei). A 50‐day study was conducted with juvenile (3.2 g) shrimp stocked in 16 800 L tanks at a stocking density of 250 shrimp m^?3. Control of total ammonia concentration was performed by the addition of combined mixtures of soybean and sugarcane molasses to the culture water. Three different molasses treatments were evaluated using different soybean‐to‐sugarcane molasses ratios: 15–85%, 38–62% and 60–40% respectively. The control group was treated only with sugarcane molasses. Water quality, chlorophyll a concentration, heterotrophic bacterial load, Vibrio spp. concentration and zootechnical indexes were all evaluated. Total ammonia concentration was controlled by heterotrophic and chemotrophic pathways. Biofloc formation, as quantified by measuring the total suspended solids, was not altered. The Vibrio spp. concentration showed a significant reduction in treatments with soybean‐to‐sugarcane molasses ratios of 38–62% and 60–40%. All combined mixtures of soybean and sugarcane molasses could maintain water quality and productivity in the superintensive culture of L. vannamei using the biofloc system. Thus, the potential use of a residue from agroindustry as a carbon source in a biofloc culture is demonstrated.     

Effect of sediment on growth and survival of post-larval Litopenaeus stylirostris (Boone, 1931)

The sediments from four areas that are used or will be used for shrimp culture were evaluated for their effect on post‐larvae growth of Litopenaeus stylirostris. Texture, organic matter, total, and bio‐available fraction of phosphorus, manganese, iron, zinc, copper, and cadmium of the sediments were measured. A positive significant correlation was obtained between total and bio‐available concentrations of iron, cadmium, and manganese, but not for copper, phosphorus, or zinc. Significant differences in final weight, survival rates, and shrimp yield were obtained among treatments. The highest survival rates were obtained with sediments that had the highest manganese levels. This survival high rate was significantly correlated with total manganese content of the sediment (r=0.92). The highest final weight were obtained in treatments with sediments containing higher levels of phosphorus, which was reinforced by a significant positive correlation between final weight and total and bio‐available phosphorus (r=0.94 and 0.95 respectively), while final weight seems adversely affected by high concentrations of copper (r=?0.83) in the sediment. Texture of the sediment influenced shrimp yield, with lower values for sandy sediments relative to silty sediments.