桑沟湾夏季栉孔扇贝养殖笼内水质变化

以2006年桑沟湾筏式养殖的栉孔扇贝为研究对象,测定了网笼内的水质状况及栉孔扇贝的死亡率,探讨了污损生物的可能影响。结果表明,(1)经过7个月的养殖,初始密度低于30个/层的实验组,栉孔扇贝的死亡率低于6%;高密度实验组(40个/层)的死亡率高达27%;(2)网笼内、外的磷酸盐、硅酸盐浓度没有显著性差异,但是,7、8月份的氨氮浓度差异较为明显;(3)同营养盐浓度的变化相比,网笼内、外叶绿素a浓度的变化较大,在9月份,高密度组的网笼内叶绿素a浓度低于0.67mg/m3,食物可能为高密度组扇贝生长、存活的限制因子;(4)8月份,高密度组网笼内的细菌总数显著高于笼外及其他密度组。分析认为,高温期网笼内的水质状况及食物限制可能与养殖栉孔扇贝的死亡有关。     

闽江河口养虾塘水体可溶性有机碳、营养盐和叶绿素a浓度变化特征

为揭示河口区陆基养虾塘可溶性有机碳(DOC)、营养盐、叶绿素a时空动态变化及其生态化学计量特征,在福建省闽江河口鳝鱼滩选择3个陆基养虾塘作为研究对象,于2018年5—10月原位测定养虾塘水温、pH、盐度、溶解氧指标,并采集不同深度水样,实验室测定DOC、可溶性无机氮(DIN)、磷酸盐(PO_4~(3-)-P)、叶绿素a浓度,探讨其主要影响因素。结果表明,养虾塘水体中DOC、DIN、PO_4~(3-)-P和叶绿素a质量浓度分别介于5.73～16.79 mg·L~(-1)、0.04～1.80 mg·L~(-1)、0.03～0.16 mg·L~(-1)和15.02～443.08μg·L~(-1),均存在明显的时空变化特征;养虾塘水体DOC、营养盐、叶绿素a浓度受到养殖水体水环境参数、人为活动、养殖生物的共同影响;养虾塘水体碳(C)、氮(N)、磷(P)营养元素组成与植物、土壤之间具有相似性,并且表现为碳盈余和氮限制。在养殖过程中,加强对养虾塘水体营养盐和叶绿素a的动态变化监测,通过人为方式调节养虾塘水体C、N、P比率,对于防止养虾塘水体富营养化,促进养虾塘生态系统绿色可持续生产具有重要作用。     

渤海中部冬夏季叶绿素a和营养盐结构影响因素对比分析

根据2016年1月(冬季)和6月(夏季)渤海中部叶绿素a(Chl a)、营养盐等数据,对Chl a和营养盐的季节特征、影响因素及趋势变化进行分析,结果表明,Chl a和营养盐呈现明显的季节变化特征(P0.01)。冬季受洋流输入、扰动再悬浮及矿化释放等因素影响,DIN、PO■-P和SiO■-Si含量分别为(10.51±4.52)μmol·L~(-1)、(0.28±0.14)μmol·L~(-1)和(10.63±2.09)μmol·L~(-1),其中DIN主要组分为NO~-_3-N(92%),除部分站位呈现磷潜在限制外,氮硅营养盐限制状况不明显。Chl a含量较低为(0.99±0.25) mg·m~(-3),主要受温度限制(T8℃)。夏季受径流输入、北黄海水交换以及吸收利用等因素影响,DIN、PO■-P和SiO■-Si含量分别为(4.72±4.2)μmol·L~(-1)、(0.04±0.04)μmol·L~(-1)和(3.81±1.72)μmol·L~(-1),较冬季分别降低55.0%、85.7%和64.1%,其中DIN以NH~(4+)-N(48%)和NO~-_3-N(45%)为主。营养盐呈现明显的P限制,且部分站位DIN和SiO■-Si含量低于阈值,不利于浮游植物的生长。Chl a含量达(4.58±5.51) mg·m~(-3),为冬季的4.6倍。在黄河口和莱州湾外高营养盐海域,Chl a含量高达10 mg·m~(-3),存在爆发藻华的风险。     

石膏法测定海水流速

为了测量浅海扇贝养成笼内、外环境因子的变化差异，利用石膏法测定了桑沟湾扇贝养殖海区、养成笼内的海水流速变化，并与挪威产SD6000型自动记录海流计进行了比较。同时，时影响石膏块溶解的因子进行了探讨，得出了石膏块的溶失与水体积、温度、盐度、时间、水流之间的相关曲线。结果表明，石膏块的溶失与水流流速之间具有很好的相关性(R^2=0．982)，经校正后石膏法测得的笼外平均海流流速与海流计测得的流速之间没有显著性差异(P=0．411)。     

大连獐子岛海域虾夷扇贝养殖容量

现场测定了獐子岛海域的叶绿素a浓度、初级生产力的季节性变化和养殖虾夷扇贝的种群结构;采用生物沉积法,测定了不同规格的虾夷扇贝的滤水率和虾夷扇贝的基本生物学特性.调查结果显示,叶绿素浓度在1.23～2.85 mg·m-3范围内,均值为(1.78±0.57)mg·m-3;初级生产力的平均值为(76.6±41.9)mg C·m-2·d-1,虾夷扇贝单位个体的滤水率为(0.55±0.25)L·h-1.结合虾夷扇贝的年产量、海域面积和有关的水文状况等数据,计算了食物限制性指标的数值,摄食压力和调节比率在0.05和1.0之间,而滤水效率小于0.05.结果显示,由于该海域的叶绿素浓度和初级生产力水平较低,海水流速大,因此,水交换带来的悬浮颗粒物为主要食物来源.目前的虾夷扇贝的养殖量(32亿粒)接近生态容量,如果开展筏式养殖,利用整个海域的水体,养殖量增大20倍的空间并达到养殖容量,预计年产量将达到256亿粒.     

牡蛎塭池中多环芳烃的分布、来源和生态风险评价

研究了长沙湾牡蛎塭池环境中多环芳烃的含量分布及其对养殖牡蛎质量安全的潜在风险。结果显示,牡蛎塭池水体、悬浮物、养殖牡蛎和沉积物中多环芳烃质量浓度分别为6.62~21.2 ng·L~(-1)(均值9.87 ng·L~(-1))、92.9~355μg·kg~(-1)(均值198μg·kg~(-1))、12.7~17.4μg·kg~(-1)(均值15.5μg·kg~(-1))和247~615μg·kg~(-1)(均值322μg·kg~(-1))。塭养区悬浮物平均含量高于塭养区外,但是差异不显著。塭养区水中多环芳烃平均含量与塭养区外相近,悬浮物中多环芳烃含量高于塭养区外,而沉积物中多环芳烃含量均值低于塭养区外。表层沉积物多环芳烃组成以3环为主,其次是4环。来源解析表明该区域多环芳烃主要源自化石燃料的燃烧,受养殖区周边燃煤发电工业的影响。风险评价结果显示,塭养区表层沉积物中多环芳烃含量低于效应区间低值,对养殖牡蛎安全潜在风险小,但是芴和蒽等同系物的含量介于效应区间低值和中值之间,可能会对塭养牡蛎养殖安全产生负面影响。     

全自动固相萃取-超高效液相色谱法测定淡水养殖水体中的呋喃丹

本文建立了淡水养殖水体中呋喃丹的全自动固相萃取-超高效液相色谱检测方法。选取HLB固相萃取小柱作为水样的富集和净化小柱,水样以5 mL·min~(-1)的速度上样,用10 mL甲醇洗脱。洗脱液经浓缩、定容后,采用超高效液相色谱-荧光检测法分析,色谱柱为ACQUITY UPLC BEH C_(18)柱(100 mm×2.1 mm,粒径1.7μm),流动相为乙腈-水(40∶60,V/V),流速为0.200 mL·min~(-1),激发波长为270 nm,发射波长为310 nm。呋喃丹在20~1 000μg·L~(-1)范围内线性关系良好,相关系数R~20.999,方法检出限为0.100μg·L~(-1),定量限为0.250μg·L~(-1),在0.250、2.50、10.0μg·L~(-1)三种加标浓度水平下,平均加标回收率为90.4%~96.3%,相对标准偏差为2.55%~5.10%。该方法自动化程度高、操作简便、快速准确、稳定性好,适用于淡水养殖水体中呋喃丹的测定。     

低氧和酸化胁迫对大黄鱼早期发育阶段消化生理的影响

为探究大黄鱼(Larimichthys crocea)早期发育阶段低氧和酸化胁迫对其消化生理的影响,实验设置4个处理组,分别为对照组[溶解氧(DO)=7.0 mg·L~(-1),pH=8.1]、低氧组[溶解氧(DO)=3.5 mg·L~(-1),pH=8.1]、酸化组[溶解氧(DO)=7.0 mg·L~(-1),pH=7.3]和低氧-酸化组[溶解氧(DO)=3.5 mg·L~(-1),pH=7.3],每个处理组4重复,每个重复放置大黄鱼受精卵4.0×10~4粒,并在实验开始后(记录为0 d)和受精卵孵化后1 d、3 d、5 d、10 d、15 d、20 d、27 d分别测定其淀粉酶、胰蛋白酶和脂肪酶活性。实验结果表明:低氧胁迫对大黄鱼早期发育阶段消化酶活性的影响均较为明显;其中对淀粉酶活性的影响主要发生在10 d以后;对胰蛋白酶活性的影响更为明显,其酶活性在前10 d各时间点均显著高于对照组。低氧胁迫和酸化胁迫对脂肪酶活性的影响均主要发生在5～10 d仔鱼刚开口阶段,此阶段低氧胁迫和酸化胁迫均导致脂肪酶活性相比同期对照组显著降低。酸化胁迫对胰蛋白酶的影响则主要体现在5 d之前,导致此阶段胰蛋白酶活性明显较高。低氧-酸化双重胁迫对大黄鱼早期发育阶段消化酶活性的影响相比单一因子胁迫有一定的加剧作用。     

循环流水水产养殖系统接种商品硝化菌的试验研究

与接种成熟滤料等方法相比,利用商品硝化菌接种生物滤器来源广泛,操作简便。本文使用一种商业上已取得一定成功的商品硝化菌液接种循环流水水产养殖系统试验模型的生物滤器。试验开始时定期接人20mL菌液(细菌含量1.5×10~10CFU·mL~(-1))以处理400g饲料产生的4.27mg·L~(-1)氨氮(TAN),12d后TAN浓度低于0.05mg·L~(-1),20d后NO_2~- -N浓度降至同样水平。在为期30d的检验期中,系统内养殖2.15kg·m~(-3)淡水白鲳,日喂饲率2％。期间养殖池TAN最大值0.465mg-L~(-1),最小值0.393mg·L~(-1),平均值0.427±0.019mg·L~(-1);NO_2~- -N最大值0.062mg·L~(-1),最小值0.038mg·L~(-1),平均值0.052±0.007mg·L~(-1);EC呈线性上升状态,每周增加32.8 μs·cm~(-1);而pH呈线性下降,每周降低0.24。系统结束时生物滤器含细菌8.65×10~6CFU·mL~(-1),水质除TP超标外,其余指标均符合我国淡水水产养殖水质标准,在2.1％～1.4％的日喂饲率下淡水白鲳日增重为1.91g,饲料系数1.164。     

河北扇贝养殖海域叶绿素a含量分布特征及初级生产力估算

干2004年9月--2005年11月,对河北扇贝养殖区海域进行了10个航次的叶绿素a含量调查。调查结果表明：（1）养殖区海域表层海水中叶绿素a平均浓度为0．73～4．44μg／L，叶绿素a浓度月均值周年变化呈单峰型。最大值出现在3月份。（2）叶绿素a平均浓度区域分布为：近岸海区〉中岸海区〉远岸海区，呈现从近岸海区向远岸海区逐渐降低趋势。（3）测区初级生产力均值变化范围为52．09～1390．3mg C／m^2·d，最低值出现在11月份．最高值出现在6月份,10个航次总平均值为311．74mgC／m^2·d。海区的营养盐、浮游动物及养殖贝类的摄食是制约影响调查海区叶绿素a周年变化和空间分布的主要因素。     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

美人鱼发光杆菌对凡纳滨对虾非特异性 免疫功能及抗病力的影响

在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。     

Effects of Spirulina platensis as a feed additive on growth and coloration of blue dolphin cichlids (Cyrtocara moorii Boulunger, 1902)

This study was carried out to investigate the effects of replacing fish meal with dietary Spirulina as a feed supplement on the growth performance and coloration of blue dolphin cichlids (Cyrtocara moorii). Five isonitrogenous (47% crude protein) and isocaloric (17.36 kJ/g digestible energy) diets were for formulated to replace FM with 0, 5, 10, 15 and 20% Spirulina (designated as Control, SP5, SP10, SP15 and SP20 respectively) and fed to the fish (initial body weight, 3.15 ± 0.01 g). Fish were randomly distributed into fifteen 120 L aquariums (26.5 ± 1.00°C), 15 fish per aquarium. The diets were tested in triplicate for 12 weeks. Experimental groups were fed twice daily (09:00 and 17:00) by hand to satiation. At the end of the feeding trial, significantly (p < 0.05) higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and lower feed conversion ratio (FCR) were observed in fish fed the SP10 diet when compared to the SP20 diet. There was no significant difference in these parameters between the other groups. The skin coloration of blue dolphin cichlid fed a diet containing Spirulina meal was enhanced. The best coloration was observed in the SP15 group. These impressions were objectively validated by chemical determinations of carotenoids extracted from fish skins and passed statistical tests of significance. The study findings show that Spirulina meal does not diminish growth rates except at very high levels.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

Sea bream culture in Egypt; status, constraints and potential

Marine fish farming in Egypt began in 1976 with the culture of gilthead sea bream, (Sparus aurata) as this fish was notably adaptable to brackish and marine pond conditions. Today, marine fish and shrimp farms amount to about 19,000 ha, out of which 42% is already in production while the rest, i.e., 58% is still under construction. In 1997, cultured gilthead sea bream production of 2,250 tons made up 3% of the 75,000 tons total aquaculture catch. In polyculture, usually with the grey mullet and sea bass, gilthead sea bream contributed 440 kg ha^–1 to the total yield of 1,700 kg ha^–1 (26%) over a period of 16 months. For the same period, the yield of monoculture ponds averaged 100 kg ha^–1, while in marine cages, yields ranged from 4–10 kg m³. In 1996–1997, fry of 0.25–1 g and fingerlings 1–10 g with a total of 3 million, were collected from the wild and 1 million fry were produced in the three marine hatcheries out of the four existing ones. The development of sea bream culture in Egypt is now severely inhibited by the shortage of seeds and adequate feeds. Exports of both sea bream and sea bass, during 1994–1996 averaged 1,300 tons per year.     

Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala (Hamilton)

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg^?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg^?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg^?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg^?1 diet (0.096–0.179 μg thiamin kJ^?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg^?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg^?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg^?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg^?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.     

Fertilization by refrigerator stored sperm of the Indian major carp, Labeo calbasu (Hamilton, 1822)

This study reports on the spermatological properties, and on the development of a protocol for refrigerator storage (4°C) of Labeo calbasu (Hamilton, 1822) sperm for artificial breeding. Volume, motility, concentration and pH of the freshly collected sperm were 2.21 ± 0.53 (μL g^?1 of fish weight) (mean ± SD), 95 ± 1 (%), 1.93 ± 0.44 × 10⁹ (cells mL^?1) and 7.56 ± 0.17 respectively. Sperm activation was evaluated at different osmolalities of NaCl solution, and motility ceased completely when osmolality of the extender was ≥287 mOsmol kg^?1. Sperm retained motility for 24, 72 and 108 h, after refrigerator storage when sperm were undiluted, suspended in Alsever's solution and suspended in Alsever's solution containing 5% methanol respectively. Fertilization rate of fresh eggs with sperm stored at 4°C in Alsever's solution and Alsever's solution containing 5% methanol was 77% and 60% with a hatching rate of 60% and 43% respectively. The fertilization and hatching success of the stored sperm suggests potential to use refrigeration for transporting genetic material to hatcheries for artificial breeding of L. calbasu in Bangladesh.     

A novel approach to denitrification processes in a zero-discharge recirculating system for small-scale urban aquaculture

This paper presents an innovative process to solve the nitrate build-up problem in recirculating aquaculture systems (RAS). The novel aspects of the process lie in a denitrification bioreactor system that uses solid cotton wool as the primary carbon source and a unique degassing chamber. In the latter, the water is physically stripped of dissolved gaseous O₂ (by means of a Venturi vacuum tube), and the subsequent denitrification becomes more efficient due to elimination of the problems of oxygen inhibition of denitrification and aerobic consumption of cotton wool. The cotton wool medium also serves as a physical barrier that traps organic particles, which, in turn, act as an additional carbon source for denitrification. Operation in the proposed system gives an extremely low C/N ratio of 0.82 g of cotton wool/g of nitrate N, which contributes to a significant reduction of biofilter volume. The additional advantage of using solid cotton wool as the carbon source is that it does not release organic residuals into the liquid to be recycled. Operation of the system over a long period consistently produced effluents with low nitrate levels (below 10 mg N/l), and there was only a very small need to replace system water. The overall treatment scheme, also incorporating an aerobic nitrification biofilter and a granular filtration device, produced water of excellent quality, i.e., with near-zero levels of nitrite and ammonia, a sufficiently high pH for aquaculture, and low turbidity. The proposed system thus provides a solution for sustainable small-scale, urban aquaculture operation with a very high recovery of water (over 99%) and minimal waste disposal.     

Effects of metomidate anaesthesia or transfer to pur sea water on plasma parameters in ammonia-exposed Atlantic salmon (Salmo salar L) in sea water

Atlantic salmon (Salmo salar L) postsmolts weighing 150 ± 53 g were exposed to 14–15 mg l^–1 TA-N (total ammonia-N) in sea water in 1 m³ tanks for 24h. Blood samples were then taken A) immediately after the fish were netted from the exposure tanks and stunned by a blow to the head; B) 2–20 min after the fish were transferred to 15 l of an anaesthetic solution of metomidate in ammonia-free sea water; or C) 2–20 min after the fish were transferred to 15 l of ammonia-free sea water. Plasma TA-N level was 18% lower in the anaesthetised fish compared to in the fish sampled directly from the exposure tanks (p 0.05), and accordingly 16% lower in the fish transferred to pure sea water although this difference was not significant (p = 0.07). Plasma glucose level was higher in the fish transferred to pure sea water than in the fish receiving the two other treatments (p 0.05), but plasma urea, osmolality, Na^{+, Cl–, Ca2+ or Mg2+} levels did not vary significantly between the different treatments. Plasma TA-N level increased with time in the fish in the metomidate solution (p 0.02).