提高罗氏沼虾单位水体出苗量试验

１９９１－１９９２年利用对虾育苗进行了提高罗氏沼虾单位水体出苗量试验。１５个试验池总水体７９．５ｍ＾３，共出虾苗４０４．２３万尾，平均５．０８万尾／ｍ＾３，最高６．３５万尾／＾３．１９９２年１２月专家鉴定认为，本成果达国内先进水平。     

黑Jun工厂化育苗技术研究

研究了亲鱼选择、暂养和苗种的饵料转换、日常管理和病害防治等一套工艺流程，在３００ｍ＾３育苗水体中，育出２６．７ｍｍ以上黑Ｊｕｎ鱼苗３２．１５万尾，鱼苗培育成活率３３．５％。专家鉴定认为，本成果总体达国内先进水平，其中产仔率、单位水体出苗量等方面属国内领先。     

利用海带育苗池培育黑鲪苗及苗种的疾病防治

将在近海捕获的１４尾黑亲鱼放在海带育苗池内进行流水培育，让其自然产仔。共产健康仔鱼３６１４００尾，产仔率达２８．５７％。以小球藻、轮虫、卤虫幼体、少量海捕天然浮游动物和鱼、虾肉糜为系列饵料，培育２０～３０天，育出全长１４．２～３０ｍｍ的稚鱼３２２１９８尾，平均成活率８９．１５％；单位水体平均出苗量为６７１２尾／ｍ３。在１８～２４℃水温范围内，仔稚鱼的平均日增长量约为０．５ｍｍ。每３～５天轮流使用１ｍｇ／１的氯霉素，０．３ｍｇ／ｌ的鱼虾安，可以有效地防治仔稚鱼的细菌性疾患；用０．０５ｍｇ／ｌ的孔雀石绿药浴１５～２０分钟，可以防治真菌疾患。     

利用海带育苗池培育黑Jun苗及苗种的疾病防治

将在近海捕获的１４尾黑Ｊｕｎ亲鱼放在海带育苗池内进行流水培育，让其自然产仔。共产健康仔鱼３６１４００尾，产仔率达２８．５７％。以小球藻、轮虫、卤虫幼体、少量捕天然浮游动物和鱼、虾肉糜为系列饵料，培育２０－３０天，育出全长１４．２－３０ｍｍ的稚鱼３２２１９８尾，平均成活率８９．１５％；单位水体平均出苗量为６７１２尾／ｍ＾３。     

中草药防治河蟹溲苗病害的研究

用中草药防治溲苗病害的试验，育苗水用ＣｕＳＯ４处理，用黄芩和五倍子配合使用，可保证后期天然海水育苗的顺利进行，黄岑浓度为１．５－２ｇ／ｍ＾３，五倍子浓度为１．－１５ｇ／ｍ＾３。     

虾夷马粪海胆人工育苗的研究↑（*）

虾夷马粪海胆１９８９年５月从日本北海道引入大连，初引进海胆壳径为０．５～１．３ｃｍ，养至１９９０年１０月性成熟并进行首次育苗，培育出Ｆ１代，其后１９９３年～１９９５年又培育出Ｆ２和Ｆ３代约５００万枚。亲海胆采取海区笼养和室内促熟方法。诱产用阴干与流水、注射０．５ＭＫＣｌ、加入性产物三种催产方法可成功获得成熟精、卵。受精卵孵化需１１．５～１２．５ｈ（１６．０～１８．５℃）达囊胚期上浮，后经二腕、四腕、六腕、八腕幼虫，以纤细角刺藻为饵料，１８～２１天（１５．０～１８．５℃）变态附着为稚海胆并摄食底栖硅藻，３０天～５０天达０．２～０．３ｃｍ以上剥离投喂石莼、囊藻、海带等，当壳径长至０．５～１．０ｃｍ以上时可下海养殖。     

河蟹可繁苗培育幼蟹技术

培育幼蟹选用２月初到３月下旬的早繁苗培育较为适宜，下苗密度控制在１００平方米放１～３公斤，随蟹苗变态调整投饵量，及时分池，促共快速生长。室外水温１５℃可起捕出售。     

锯缘青蟹北方工厂化育苗技术

威海市羊亭水产养殖总公司１９９８和１９９９两年进行了锯缘青蟹的工厂化育苗，均取得成功，现将其育苗技术介绍如下：１方法１．１亲蟹亲蟹均来自当年南方越冬蟹，１９９８年８只，１９９９年１５只，平均体重２７０ ｇ，最大个体５５０ ｇ。１．２育苗设施育苗用 ４０ ｍ３水泥池 ５个，水深１．５ｍ，池内设有盘管式加温设施，并有充气设施。同时配有单胞藻、卤虫和轮虫培养池。１．３亲蟹暂养促熟亲蟹从南方运回后，首先放入池中暂养，使其恢复体力，促使性腺进一步发育。暂养池底部，除留出投饵台外，其它地方均铺设 １０ ｃｍ厚的砂…     

黑鲷幼鱼对饵料蛋白质,脂肪,糖类需求量的研究

实验了９种人工配合饵料，其中，蛋白质，脂肪和糖类含量为４１．２％，１７．６％和１５．９％的４号饵料，使黑鲷幼鱼生长最快，实验４３天，幼鱼增重率为６４．３％，饵料系数为１．３。     

皱纹盘鲍与光棘球海胆筏式混养研究

皱纹盘鲍与光棘球海胆的混养可有效地防治污损生物的附着。综合分析鲍与海胆的生长、存活及防污损生物附着的效果，在生长期、高温期和恢复生长期混养海胆的最适密度分别为１５．２０个／格和１５－２０个／格。     

栉孔扇贝三倍体与二倍体的排泄研究

从温度变化、个体大小和昼夜变化等３个角度研究栉孔扇贝（Ｓｃｈｌａｍｙｓ ｆａｒｒｅｉ）三倍体与二倍体的排泄率。结果表明，栉孔扇贝三倍体与二倍体的排泄率均随温度升高而增大；不同壳宽排泄率（Ｎ）与温度（ｔ）的关系为：Ｎ＝７．２０３３ｅ＾０．１２１５ｔ，Ｒ＾２＝０．８４４１（三倍体ｓ组，壳宽约３．２ｃｍ）；Ｎ＝８．８１５３ｅ＾０．１０３１ｔ，Ｒ＾２＝０．９８６３（三倍体ｂ组，壳宽约４．３ｃｍ）；Ｎ＝６．     

Effects of Ambient Nitrite on Amazon River Prawn,Macrobrachium amazonicum,larvae

The effects of nitrite concentration on larval development of Amazon river prawn, Macrobrachium amazonicum, were studied in laboratory. In Experiment 1, larvae were reared in 600‐mL glass beakers filled with 300‐mL water with nitrite concentration of 0, 0.2, 0.4, 0.8 and 1.6 mg/L NO₂‐N. In Experiment 2, total ammonia nitrogen (TAN, NH₃‐N + NH₄‐N) excretion were analyzed in zoea (Z) I, III, VII and IX exposed to 0, 0.4, 0.8 and 1.6 mg/L NO₂‐N. In both experiments each treatment was conducted in five replicates. The experiments were carried out in test solutions at 10 salinity, constant temperature 30 C and 12:12 h daylight : darkness regime. Survival, productivity, weight gain and larval stage index decreased linearly with increasing ambient nitrite concentration. However, there was no significant difference among larvae reared at concentration ranging from 0 to 0.8 mg/L NO₂‐N by ANOVA in all variables. Individual ammonia‐N and mass‐specific ammonia‐N excretion increased in ZI and ZIX, was almost constant in ZIII and decreased in ZVII from 0 to 1.6 mg/L NO₂‐N. The relationship between individual TAN and body mass suggested that 1.6 mg/L NO₂‐N stress the larvae. Despite of the effects of nitrite on larvae follow a dose‐dependent response and shows large variability among individuals, levels below 0.8 mg/L may be used as a general reference in commercial hatcheries, which should be applied carefully.     

Larval Development of the Giant River Prawn Macrobrachium rosenbergii at Different Ammonia Concentrations and pH Values

The effect of ammonia and pH levels on giant river prawn Macrobrachium rosenbergii larvae were evaluated to provide science-based information on safe levels of ammonia and pH for larviculture. Survival rate, developmental stage, and larval weight gain were determined for larvae kept in water with total ammonia (NH ₄-N)concentrations of 0, 1, 2, 4, and 8 mg\L and pH 7, 8, and 9. The trials were conducted in two phases: phase 1, larvae from stages I through VIII and phase 2, larvae from stage VIII until metamorphose. Oxygen consumption was determined for larvae in stages I and VIII at total ammonia concentrations of 0, 4, and 8 mg/L and pH 8. Survival rate up to stage VIII varied from 86 to 98% and did not differ for total ammonia concentrations in pH 7 and 8 and for 0 mg/L NH₄ N in pH 9. Survival rate was significantly lower (0–20%) for total ammonia concentrations from 1 to 8 mg/L (0.43–3.41 mg/L of unionized ammonia) in pH 9. Larval stage indexes (7.9–8.0 range) and weight gain (1.572–2.931 mg range) of larvae at the end of phase 1 of the experiment did not differ for the different ammonia concentration solutions, but were significantly lower in pH 9. In phase 2, no parameter differed among treatments for pH 7 and 8; however there was total mortality at pH 9 until 96h. Respiration rates diminished when larvae were exposed to total ammonia concentrations of 4 and 8 mg/L (0.28 and 0.55 mg/L of unionized ammonia), but development remained unaltered. Therefore, M. rosenbergii larvae tolerate high levels of total ammonia, while toxicity depends primarily on unionized ammonia concentrations. In addition, alkaline pH (9) acted directly on the larvae, curbing development and causing severe mortality. Larval tolerance to high ammonia and pH levels decreases for the last zoeal stages.     

Ammonia tolerance of Litopenaeus vannamei (Boone) larvae

The tolerance of Litopenaeus vannamei larvae to increasing concentrations of total ammonia nitrogen (TAN) using a short‐term static renewal method at 26°C, 34 g L^?1 salinity and pH 8.5 was assessed. The median lethal concentration (24 h LC₅₀) for TAN in zoea (1‐2‐3), mysis (1‐2‐3) and postlarvae 1 were, respectively, 4.2‐9.9‐16.0; 19.0‐17.3‐17.5 and 13.2 mg L^?1TAN (0.6‐1.5‐2.4; 2.8‐2.5‐2.6 and 1.9 mg L^?1 NH₃‐N). The LC₅₀ values obtained in this study suggest that zoeal and post‐larval stages are more sensitive to 24 h ammonia exposure than the mysis stage of L. vannamei larvae. On the basis of the ammonia toxicity level (24 h LC₅₀) at zoea 1, we recommend that this level does not exceed 0.42 mg L^?1 TAN – equivalent to 0.06 mg L^?1 NH₃‐N – to reduce ammonia toxicity during the rearing of L. vannamei larvae.     

Acute Toxicity of Ammonia and Nitrite to Painted River Prawn,Macrobrachium carcinus,Larvae

This study evaluated the toxicity of ammonia and nitrite to different larval stages of Macrobrachium carcinus. Three replicated groups of larvae in the zoea stages II, V, and VIII (hence named Z₂, Z_5, and Z₈, respectively) were exposed separately to five ammonia (5, 10, 20, 40, and 80 mg total ammonia nitrogen [TAN]/L) and six nitrite concentrations (5, 10, 20, 40, 80, and 160 mg NO₂‐N/L), plus a control treatment with no addition of ammonia and nitrite, at a salinity of 20 g/L. The ammonia LC₅₀ values at 96 h for Z₂, Z₅, and Z₈ were 8.34, 13.84, and 15.03 mg TAN/L (0.50, 0.71, and 0.92 mg NH₃‐N/L), respectively, and the nitrite LC₅₀ values at 96 h for Z₂, Z₅, and Z₈ were 3.28, 9.73, and 34.00 mg NO₂‐N/L, respectively. The estimated LC₅₀ values for NO₂‐N were lower than those for TAN in most of the stages evaluated. This observation suggests that M. carcinus larvae are more tolerant to ammonia, except at Z₈, in which larvae had a higher tolerance to nitrite. Based on the lethal concentrations at 96 h, it may be concluded that the tolerance of M. carcinus to ammonia and nitrite increases with larval development. Safe levels were estimated to be 0.834 mg TAN/L (0.05 mg NH₃‐N/L) and 0.328 mg NO₂‐N/L; therefore, efforts should be made to maintain lower concentrations of these compounds throughout the larval rearing of M. carcinus.     

饵料卤虫的营养强化对黑斑口虾蛄(Oratosquilla kempi) 幼体消化酶活力及其抗逆性的影响

用扁藻、酵母和"鱼油 酵母"强化3种方式处理的卤虫无节幼体投喂黑斑口虾蛄幼体,对各组黑斑口虾蛄幼体消化酶活力和抗逆性差别分析。结果显示,经过"鱼油 酵母"强化的幼体对氨氮、福尔马林、饥饿和盐度的耐受性均强于对照组。经过扁藻和"鱼油 酵母"强化的第Ⅲ相幼体脂肪酶活力是对照组的3倍,经过酵母和"鱼油 酵母"强化的仔虾蛄幼体脂肪酶活力较高。在第Ⅲ相幼体中淀粉酶活力为扁藻>酵母>对照>"鱼油 酵母"强化,仔虾蛄中酶活力为扁藻>对照>酵母>"鱼油 酵母"强化。在酵母强化第Ⅲ相幼体和对照组仔虾蛄中纤维素酶活力最高。第Ⅲ相幼体对照组的胃蛋白酶和类胰蛋白酶活力均为最高,而"鱼油 酵母"强化仔虾蛄幼体的胃蛋白酶和类胰蛋白酶活力均高于对照组。黑斑口虾蛄幼体消化酶活性和抗逆性能力的变化趋势与其成活率、变态率、生长速度、EPA和DHA含量变化趋势相同,可以作为评价饵料质量好坏的重要指标。     

Use of fluidized bed biofilter and immobilized Rhodopseudomonas palustris for ammonia removal and fish health maintenance in a recirculation aquaculture system

Intensive recirculating aquaculture relies on biofilters to sustain satisfactory water quality in the system. Fluidized bed and immobilized cell technologies were used to remove ammonia from the water and maintain fish health. A high‐rate nitrifying fluidized bed biofilter combined with valveless filter was designed for use in a recirculation aquaculture system (RAS). The suspended solids produced during fish culture could automatically be removed using a valveless filter. Natural porosity with fitting proportion, steady fluidization and expanding rate was chosen as the fluidized carrier. The technology of bacterial separation and cultivation was used. The immobilized Rhodopseudomonas palustris (R. palustris) produced through a biotechnologically embedding medium is suitable for fish and could help prevent diseases. Nitrification was promoted through the selective rearing of nitrobacteria in a fluidized bed biofilter. Water quality was improved using fluidized bed biofilter and immobilized R. palustris in the RAS. In addition, the proposed system was able to reduce costs. Maximum fish load was 45 ± 3 kg m^?3 in the closed recirculating water fish culture system, and water use was reduced by 80–90%. The total ammonia nitrogen removal rate of the technology was 80–95%, and nitrite N removal rate was above 80%.     

Degradation of urea,ammonia and nitrite in moving bed biofilters operated at different feed loadings

This study investigated how removal rates of urea, ammonia, and nitrite in laboratory scale moving bed biofilters were affected by long-term feed loading. To generate different loadings, five identical freshwater flow-through systems (100 l/h) with rainbow trout (Oncorhynchus mykiss) were fed increasing fixed rations of a commercial diet. The filtered effluent from each system was lead through a moving bed biofilter installed end-of-pipe. After an acclimatization period of four months, the moving bed biofilters were spiked separately with urea, ammonia and nitrite in batch mode in three successive trials to investigate degradation kinetics. Results showed that urea, in addition to ammonia and nitrite, was degraded although the substrate limited/dependent removal rate of urea (first order kinetic) was lower than that of ammonia and nitrite. Degradation of urea could be described as first order kinetics below 2.5 mg N/l. Degradation of total ammonia nitrogen (TAN) and nitrite was substrate independent (zero order kinetic) above 2 mg N/l and subsequently substrate dependent as substrate concentrations in the bulk water declined. The transition zone from zero to first order degradation was elevated with increase in long-term biofilter loading. For ammonia and nitrite, a significant increase in the zero order removal rate constants related to long-term loading were observed up to a long-term feed loading of 207 g/d, corresponding to 69 g feed/m² filter media/d and an TAN + urea-N concentration of 2.70 mg N/l. Long-term feed loading had no obvious effect on first order removal rate constants of any of the three nitrogenous compounds. Degradation of urea resulted in generation of ammonia demonstrating that urea degradation contributes to the ongoing nitrification activity in aquaculture biofilters. For all three types of spiking (urea, ammonia and nitrite) accumulation of nitrate was observed in the moving bed biofilters, sustaining that nitrification had occurred.     

Effects of acute and chronic toxicity of unionized ammonia on mud crab, Scylla serrata (Forsskål, 1755) larvae

While the effects of ammonia on fish and prawn larvae are well documented, little is known of its effect on mud crab (Scylla serrata) (Forsskål, 1755) larvae. Two experiments were conducted in 5 L hemispherical plastic bowls, containing 3 L of ultra‐filtered and settled seawater and various larval stages of mud crab to (1) determine the acute median lethal concentration (LC₅₀) of unionized ammonia and (2) to determine the chronic effects of unionized ammonia on survival and percentage moulting to zoea and megalop stages. The larval stages that exhibited the highest tolerance to ammonia over 24 h were zoea 1 (LC₅₀ of 4.05 mg L^?1 of unionized ammonia) and zoea 5 (LC₅₀ of 6.64 mg L^?1 of unionized ammonia). The megalop stage had the lowest total ammonia LC₅₀ at both 24 and 48 h, making it the larval stage most susceptible to total ammonia. Exposure to 6.54 mg L^?1 of unionized ammonia resulted in 100% death of all larvae within 24 h. The tolerance of S. serrata larvae to total ammonia did not appear to increase with ontogenetic development. The results indicate that the concentrations at which total ammonia produces an acute or chronic response in mud crab larvae are far higher than those experienced in current larval production systems (0–0.5 mg L^?1 of total ammonia) used as industry standards in Australia.     

Performance of Larval Walleye Cultured Intensively in Clear and Turbid Water1

Experiments were conducted to determine the performance of larval walleye (Stizostedion vitreum) reared in clear, 0.2 nephelometric turbidity units (NTU), and turbid water, 20 or 50 NTU, on formulated feed. Larvae were cultured for 21, 28, or 30 days posthatch in four trials with 3 or 4 replicate tanks per treatment (clear and turbid) in each trial. Duration of each trial was dependent on the arrival of newly hatched larvae for subsequent trials. The desired turbidity levels were obtained by pumping a solution of clay to the culture tanks every 20 (trial 1) or 30 min (trials 2, 3 and 4). Other than turbidity, all environmental conditions (dissolved oxygen, alkalinity, pH, total ammonia, un-ionized ammonia, nitrate, nitrite, chloride, and hardness) and rearing techniques were similar between treatments. Larvae were stocked at 20/L and fed formulated feed (Fry Feed Kyowa B-400 and B-700) every 3 to 7 min, 24 hours per day. Significant differences in feed acceptance and total length between larvae in the clear and turbid water were observed as early as 7d posthatch. Larvae in turbid water began eating the formulated diet one to two days before those in clear water. In all trials, survival, final length, and final weight of larvae reared in water of high turbidity were significantly greater than for larvae reared in clear water. Mean survival (±SE) for all four trials was 27.7 ± 5.6% in high turbidity water and 5.9 ± 1.3% in clear water. At the end of the trials, mean total length of the larvae reared in turbid water was at least 3.2mm (15%) greater than that in the clear water. Mean final weight of the larvae from turbid water was 2.25 times greater than larvae from clear water over the four trials. In two of the four trials, gas bladder inflation (GBI) of larvae reared in high turbidity was significantly greater than for fish reared in clear water, but the difference in GBI was not significant in the other two trials. In this study, performance of larval walleye was greatly enhanced by water with a turbidity of at least IS NTU.