凡纳滨对虾(Litopenaeus vannamei)工厂化养殖系统微藻的群落特征分析

2015年6-9月期间,对青岛市宝荣水产科技有限公司凡纳滨对虾(Litopenaeus vannamei)工厂化养殖车间的6个实验池进行采样调查,分析了水体中微藻的种类组成、丰度、多样性和优势种演替特征,并结合养殖情况进行了讨论.共检出微藻5门28属49种(其中优势种14种),丰度范围为5.2×105-9.4×108 cell/L,生物量范围为1.23-208.00 mg/L,多样性指数范围为0.42-2.44.多样性指数低于0.9时,生态系统稳定性差,对虾易发病.不同养殖阶段微藻优势种种类不同,前期主要是绿藻门(Chlorophyta)、硅藻门(Bacillarionphyta)和部分甲藻门(Pyrrophyta)的种类,中、后期以蓝藻门(Cyanophyta)的微囊藻(Microcystis sp.)和颤藻(Oscillatoria sp.)为主.对虾养殖密度显著影响微藻优势种演替,300 ind/m2养殖密度(A1池)藻相稳定且以绿藻和硅藻为优势种,对虾生长良好;400-500 ind/m2养殖密度(B1、C1和C2池)颤藻在中、后期演替成为绝对优势种,对虾易发病死亡.本研究为优化对虾工厂化养殖环境、指导养殖生产提供参考.     

The Effects of Cold Plasma Application on Quality and Chemical Spoilage of Pacific White Shrimp (Litopenaeus vannamei) during Refrigerated Storage

Pacific white shrimp (Litopenaeus vannamei) is an important species in aquaculture worldwide. Post-mortem changes during cold storage reduce the quality of shrimp and shorten its shelf life. Cold plasma (CP) was applied for 45, 90, and 150s as T₁, T₂, and T₃, respectively, to fresh harvested shrimp. The biochemical parameters and melanosis were analyzed in comparison to metabisulphite treated (T_M) and control during 12 days of refrigerated storage. The results highlighted lower rate of increase in pH, total volatile base nitrogen (TVB-N) content, thiobarbituric acid reactive substances (TBARS), free fatty acid (FFA), peroxide value (PV), and fluorescent compounds (FC) in shrimp exposed to CP and metabisulphite compared to control (P < 0.05). Although CP lowered biochemical changes in T₁ and T₃ shrimp, T₂ was the most effective treatment in reducing undesirable changes and improving quality of shrimp. In all storage periods, melanosis was significantly lower in T₂, T₃, and T_M samples. Results demonstrate that CP exposure effectively decreases relative activity of polyphenol oxidase (PPO) enzyme, and prolonging the exposure to CP for 150 s resulted in 50% reduction in enzyme activity. We conclude that application of CP for 90 s was the most efficient circumstance to extend shelf life of white shrimp during cold storage.     

混养锦鲤对微咸水凡纳滨对虾池水质及产量的影响

在6口面积均为0.4 hm2的微咸水池中养殖凡纳滨对虾,密度为7.5×105尾/hm2,其中4口混养锦鲤,密度分别为1500、3000、60001、2 000尾/hm2,研究混养锦鲤对凡纳滨对虾池水质及产量影响。结果表明:混养池水质比较稳定,透明度、NH4+-N和NO2--N波动幅度较小且数值较低,混养池对虾平均产量为3345 kg/hm2,比单养池平均产量2268 kg/hm2高47.5%,其中混养锦鲤3000尾/hm2的池虾产量最高,达到3765 kg/hm2。     

Experimental Infections with Baculovirus penaei in the White Shrimp Penaeus vannamei (Crustacea: Decapoda) as a Bioassay

Infections of the virus Baculovirus penaei (BP) have historically impacted penaeid shrimp production in both hatcheries and ponds. BP causes cytopathological alterations and mortality in at least four species, including Penueus vannamei . This study established experimental infections with BP in laboratory-reared P. vannamei . The most useful protocol involved BP infection in third substage protozoea (P₃) induced by feeding virus-contaminated material to rotifers and, in turn, feeding those rotifers to the shrimp larva. Infections were also established by delivering virus-containing brine shrimp to mysis (M) and postlarval (PL) stages. When virus originating from infected adults and juveniles was fed to P₃'s, the shrimp exhibited patent infections with hypertrophic nuclei, polyhedra, free virions, and occluded virions five or six days after being fed the virus. In contrast, when the source of virus material was from bioassay larvae rather than from adults and juveniles, similar patent infections developed in P₃'s by one to two days. A significant mortality in the resulting M's and PL's was associated with the infections with short but not long prepatent periods. In experimentally infected shrimp, examination by light microscopy and transmission electron microscopy revealed extensive viral infection in many cells in the anterior midgut and as many as 80–90% of the proximal and medial hepatopancreatic tubular cells. Free and occluded virions capable of producing disease ruptured into the gut lumen soon after infections became patent. Tests conducted in 1 L Imhoff cones, 160 L spat-cones, and aquaria all produced infections, usually with a prevalence of 100%. The system provides a useful method to detect and assay for infective agents, to amass infective material for research purposes, and to assess the biology of and host response to the virus under different conditions.     

Comparison of Physical,Thermal and Chemical Methods to Measure Protein Denaturation in Frozen Pacific Whiting (Merluccius productus)

The potential of using the torsion test and differential scanning calorimetry (DSC) to determine the effect of frozen storage on protein denaturation in fish fillets was investigated. Pacific whiting fillets were stored for 12 weeks at three temperature conditions: -20¦C, -8¦C, and at a level varying between 0 and -8¦C. Salt soluble protein (SSP) extractability and Ca++-ATPase activity were used to evaluate the torsion test and DSC. The shear strain value of the torsion test provided a good correlation with SSP extractability, Ca++-ATPase activity, and myosin transition enthalpy as measured by DSC. Therefore, shear strain can be considered as a useful tool for the determination of protein denaturation in Pacific whiting during periods of frozen storage. Because Ca++-ATPase activity, shear stress and shear strain, and myosin transition enthalpy all decreased within one week, protein deterioration in frozen Pacific whiting appears to be rapid at the temperatures tested.     

凡纳滨对虾急性肝胰腺坏死病(AHPND)病原分离鉴定及其致病性分析

本研究从患急性肝胰腺坏死病(Acute hepatopancreatic necrosis disease,AHPND)的凡纳滨对虾(Litopenaeus vannamei)肝胰腺中分离到一株优势菌,编号为20160303005-1,通过16S rRNA和分子伴侣蛋白groEL基因序列分析,并结合生理生化特征,将该细菌鉴定为副溶血弧菌(Vibrio parahaemolyticus),其血清型为O1:KUT(K untypeable)。基因分析结果显示,该菌株携带可引起对虾AHPND的相关毒力蛋白基因pirA~(VP)和pirB~(VP),但不携带副溶血弧菌临床菌株毒力基因:耐热直接溶血毒素(Thenmostable direct hemolysin,tdh)和相对耐热直接溶血毒素(TDH-related hemolysin,trh)基因。菌株对凡纳滨对虾具有较强的致病性,浸泡感染的半数致死剂量(LD_(50))为7.96×10~3 CFU/ml。对虾急性感染后,6 h肝胰腺颜色变浅,肠胃变空;9 h肝胰腺呈浅白色,萎缩变小。9 h死亡数过半,24 h全部死亡。组织病理学分析显示,感染后对虾肝胰腺小管崩塌,上皮细胞严重脱落,呈现出典型的AHPND病理症状。药敏实验结果显示,该菌对庆大霉素、环丙沙星和头孢他啶等16种药物敏感,对阿莫西林、替卡西林和头孢噻吩等5种药物表现为耐药。上述研究可为该病原的流行病学及药物防控研究提供基本数据。     

凡纳滨对虾(Litopenaeus vannamei)选育群体与杂交群体遗传多样性差异及其在低温条件下生长性能的比较

选取连续3年选育的凡纳滨对虾(Litopenaeus vannamei)群体作为选育群体(SP),选育群体与引进的凡纳滨对虾群体的杂交F1代群体(HP),探究了这2个群体在低温条件下的生长性能及遗传多样性的差异.结果显示,在生长性能方面,HP群体与SP群体的平均体重分别为(13.18±3.65)g和(12.20±3.14)g,变异系数(CV)分别为27.69％和25.74％.HP群体的体重和其他可测量性状的平均值均大于SP群体.单因素方差分析(One-way ANOVA)表明,2个群体体重(BW)和第3腹节宽(TASW)存在极显著差异(P＜0.01).HP群体的特定增长率(SGR)和绝对增重率(AGR)分别为(5.09±0.61) ％/d和(0.26±0.60) g/d,SP群体的SGR和AGR分别为(4.94±0.57) ％/d和(0.24±0.63) g/d,HP群体的SGR和AGR均极显著高于SP群体(P＜0.01),表明HP群体相对于SP群体有着明显的生长优势.在遗传多样性方面,HP群体的平均等位基因数(Na=7.9)略高于SP群体(Na=7.6).HP群体和SP群体的平均多态信息含量(PIC)分别为0.63和0.62,均为高度多态.2个群体的平均观测杂合度(Ho)分别为0.492(HP群体)和0.483(SP群体),平均期望杂合度(He)分别为0.675(HP群体)和0.663(SP群体),HP群体的He和Ho均略高于SP群体,表明HP群体相比SP群体有着更加丰富的遗传多样性.遗传分化分析表明,2个群体间遗传分化指数(Fst)为0.1556,表明群体间遗传分化水平显著.     

Effects of replacing fish oil with stearine as main lipid source in diet on growth and survival of Pacific White Shrimp,Litopenaeus vannamei (Boone, 1931)

The stearine fraction from raw fish oil refinement has been treated as a waste material. This study was conducted to evaluate effects of replacing prime refined fish oil with stearine as the main lipid source to a control diet on shrimp growth and survival as well as on pellet water stability of diets. Test diets were processed containing three levels (0.7%, 1.3% and 2.7%) of either stearine or refined fish oil in a semi‐purified control diet. These diets were each assigned to five or six replicated tanks and each tank was stocked with seventeen juvenile shrimp (ca. 0.50 g) in an indoor seawater recirculating system. At the end of 6 weeks, the survival of shrimp was 89.4–95.3% with no significant difference (P > 0.05) among dietary treatments. The six test diets obtained significantly higher (P < 0.05) shrimp growth rates (1.46–1.83 g week^?1) than the control diet (1.38 g week^?1). The shrimp that were fed the three stearine‐added diets exhibited high growth rates (1.75–1.83 g week^?1). Increasing the inclusion level of the stearine improved pellet water stability (91.7–93.9%; P < 0.05). These results suggest that stearine can replace fish oil in shrimp feed based on the growth performance.     

Physicochemical and Microbiological Changes in Dried Small-Spotted Catshark (Scyliorhynus canicula): Contributing to the Developing an Alternative Shark-Based Salted-Dried Seafood Product

Our aim is to contribute to the valorization and optimization of a salted-dried seafood product prepared from small-spotted catshark (Scyliorhynus canicula) akin to “litão seco,” the high-priced, traditional dried blackmouth catshark (Galeus melastomus). This work focused on studying the changes in physicochemical and microbiological parameters of S. canicula salted (for 3 h or 24 h) and dried (convection oven for 24 h or tray drier for 3 h). As expected, salting and drying reduced the water content and water activity, while chloride content in fillets increased. Also, significant but distinct changes in color, namely CIE L* and b*, were observed. Total viable counts were significantly reduced in the salted-dried shark, but the later still presented Staphylococcus aureus, though at marginally acceptable, non-hazardous levels. The abundance of yeasts was reduced by 3 log(cfu/g) in samples oven-dried for 24 h but only by 0.8 log after 3 h in the tray-drier. From our results, salted-dried S. canicula has the required physicochemical characteristics and microbiological quality to be apt for human consumption and is a suitable candidate for becoming a traditional seafood product comparable to “litão seco.”     

Effect of carbon and nitrogen ratio (C:N) manipulation on the production performance and immunity of Pacific white shrimp Litopenaeus vannamei (Boone, 1931) in a biofloc‐based rearing system

A 16‐week indoor culture trial was conducted to evaluate the effect of varying C:N ratio on growth performance, physico‐chemical parameters, microbial dynamics, feed utilization, and immunological parameters. The experiment comprised of five biofloc treatment groups (with varying C:N ratio 5:1, 10:1, 15:1, 20:1) and a control with three replicates each, having 100 nos/m³ as stocking density in 500 L tanks with constant aeration. The C:N ratios of the treatments were manipulated using molasses as an organic carbon source whereas there was no carbon source added in control. The water quality parameters monitored throughout the experiment were found to be within permissible limits in shrimp culture. At the end of the experiment, it was observed that there were significant differences between the treatment groups and the control regarding absolute growth, SGR, FCR, PER, and FER. Furthermore, a considerable difference in immunological parameters, namely, THC, phagocytosis, and PO activity (17.5 × 10⁶ cells per ml, 43.5%, 0.112 Units min^?1 mg min^?1), was recorded among the treatments compared to that of the control groups (6.2 × 10⁶ cells per ml, 31.5%, 0.051 Units min^?1 mg min^?1) respectively. Enhanced growth and survival with substantial disease resistance were recorded in C15 treatment. The results indicate that the CN15 ratio coupled with minimal water exchange is optimal for improved survival, growth, and immune activity.     

The replacement of fish meal with fermented soya bean meal or soya bean meal in the diet of Pacific white shrimp (Litopenaeus vannamei)

The present study evaluated the effects of replacing fish meal (FM) with soya bean meal (SM) or fermented soya bean meal (FSM) on growth, nutrient utilization, digestive enzyme activity and intestinal histology of Pacific white shrimp. The basal diet (control) contained 18% FM, and then, FM in basal diet was replaced by 1/6 (17%), 1/3 (33%) and 1/2 (50%) by the inclusion of SM and FSM, referring to SM17, SM33, SM50, FSM17, FSM33 and FSM50 respectively. The shrimp (3.0 g) were fed one of the seven diets for 8 weeks. The results showed that the control group had the highest weight gain (WG) (653.8%) and the lowest feed conversion ratio (FCR) (1.61). SM33, SM50 and FSM50 groups showed significantly lower WG, crude protein (CP) digestibility, hepatopancreatic protease, amylase activity and higher FCR than the control (p < .05). The villi height of SM33, SM50 and FSM50 groups and the intestinal wall thickness of SM groups and FSM50 group were significantly lower than those of the control (p < .05). In conclusion, fish meal (18%) in white shrimp diet could be replaced by 1/6 (17%) and 1/3 (33%) with SM and FSM respectively. Fermented soya bean meal could replace more fish meal than soya bean meal did.     

Growth modelling including size heterogeneity: Application to the intensive culture of white shrimp (P. vannamei) in freshwater

This article models the growth of a population in aquaculture, including the phenomenon of size heterogeneity. Experimental observations of six initial densities (90, 130, 180, 230, 280 and 330 shrimps m⁻²) in an intensive culture of Penaeus vannamei in freshwater were used to fit a growth model. For this, three mathematical functions were analysed (Gompertz, von Bertalanffy and Pütter), which were modified in order to include the effect of initial density. Two models were constructed, one assuming the hypothesis of homogeneous individual growth and the other including size-heterogeneity throughout the culture cycle. For the second case, a stabilisation time was evaluated which defines the future heterogeneity of the cohort. In each initial density, the stabilisation phase was reached at approximately 2 g. However, the time taken for this phase to start increased with increasing initial culture density. The modified von Bertalannfy function was the most effective of the three equations in predicting growth. The weight predictions, assuming homogeneity and variability of sizes, presented low Percentage Root Mean Square Errors (PRMSE). However, the inclusion of size variability in the fit produced better statistical results than when they were not included (PRMSE decreased from 16% to 12%). This confirms the importance of taking into account size heterogeneity at an intensive level. Particularly at the technical level when the aquaculture producer is required to make stocking and harvest plans.     

Effects of addition of Navicula sp. (diatom) in different densities to postlarvae of shrimp Litopenaeus vannamei reared in a BFT system: Growth,survival, productivity and fatty acid profile

The objective of this study was to evaluate the effect of the addition of Navicula sp. on the growth and fatty acids profile of Litopenaeus vannamei postlarvae in a biofloc system (BFT). Four treatments were used: BFT; BFT 2.5N (addition of 2.5 × 10⁴ cells/ml of Navicula sp.); BFT 5N (addition of 5 × 10⁴ cells/ml of Navicula sp.) and BFT 10N (addition of 10 × 10⁴ cells/ml of Navicula sp.), all in triplicate. The shrimp (1 ± 0.01 mg) were stocked at a density of 3,000 postlarvae/m³ and fed with commercial feed. The diatom was added every 10 days, and at the end of 42 days, shrimp performance, water quality and proximal composition were evaluated. The BFT 5N and BFT 10N treatments had higher performance values, highlighting the values of productivity (2.30 and 2.42 kg/m³) and specific growth rate (15.92 and 16.08%/day), which were higher than the other treatments. In addition, the highest levels of fatty acids were observed in treatments with diatom (BFT 5N and BFT 10N), indicating the benefits of Navicula sp. on growth enhancement and fatty acid content of L. vannamei postlarvae grown in biofloc systems.     

The role of açaí (Euterpe oleracea Mart. 1824) as a chemoprotective agent in the evaluation of antioxidant defence,oxidative damage and histology of juvenile shrimp Litopenaeus vannamei (BOONE, 1931) exposed to ammonia

This study investigated the effects of the use of the inclusion of açaí on the diet of shrimp Litopenaeus vannamei on antioxidant and histopathological responses after exposure to ammonia. The shrimps were fed two experimental diets: control and with 10% of açaí inclusion (W/W), for 35 days. Afterwards, the organisms were exposed at four concentrations of ammonia (0.01‐control; 0.26; 0.48 and 0.91 mg NH₃‐N L^?1) for 96 hr. The total antioxidant capacity (ACAP) of the gills decreased significantly in both diets when exposed to ammonia, whereas in the muscle, the açaí promoted an increase in ACAP. Concomitantly, lipid peroxidation levels increased in the gills and decreased in muscle. After exposure to ammonia, glutathione‐S‐transferase activity increased in hepatopancreas in shrimps fed with açaí facilitating the detoxification of lipid peroxidation by‐products, and the concentration of protein sulfhydryl groups decreased in the gills and muscle of the shrimp of the control diet, evidencing protein damage, an unobserved response in shrimps that received the açaí diet. Histopathological changes decreased in açaí‐fed shrimps about the control diet after exposure to ammonia. It is concluded that açaí mitigated ammonia‐induced histopathological changes, improved the antioxidant defence system (gills and muscle) and attenuated the lipid damage in the muscle.     

The feeding ecology of larval Pacific hake (Merluccius productus) in the California Current region: an updated approach using a combined OPC/MOCNESS to estimate prey biovolume

A combined optical particle counter (OPC) and multiple opening and closing net and environmental sensing system (MOCNESS) was used to obtain simultaneous measurements of the fine‐scale distribution of ‘prey‐sized’ particles and the vertical distribution of larvae of Pacific hake (Merluccius productus). Physical properties were also measured. The data were used to describe the feeding ecology of Pacific hake larvae, and to explore the effects of prey abundance, time of day, temperature and depth on feeding. Pacific hake larvae consumed a wide variety of prey including copepod eggs, nauplii, copepodites, and euphausiid metanauplii. Calanoid copepodites comprised > 75% of the ingested prey volume. First‐feeding larvae were 2.5–3.0 mm SL. These larvae consumed prey 40–200 μm wide. Larvae 3.0–6.5 mm long ingested prey 40–400 μm wide and larvae > 6.5 mm long ingested prey 400–700 μm wide. There were clear diel patterns in feeding incidence and prey volume ingested. Feeding commenced between 06:01 and 08:00 hours PST and continued until ～ 16:00 hours. Ingested prey items remained in the gut until complete gut evacuation occurred near dawn. The volume of food ingested was estimated using two indices, the cube root of the prey volume (CRPV) and the cube root of the stomach volume (CRSV). Standard length, log elapsed time since gut evacuation, depth and particle biovolume contributed significantly to variation in both indices. Temperature did not contribute to variability in either CRPV or CRSV.     

The effects of partial replacement of fishmeal protein by hydrolysed feather meal protein in the diet with high inclusion of plant protein on growth performance,fillet quality and physiological parameters of Pengze crucian carp (Carassius auratus var. Pengze)

Goal of this research is to explore the effects of graded dietary levels of hydrolysed feather meal (HFM) protein as an alternative of fishmeal protein on Pengze crucian carp (Carassius auratus var. Pengze). Five isonitrogenous (35% crude protein) diets were formulated as Control diet and four other diets F15, F30, F45 and F60 wherein 15%, 30%, 45% and 60% fishmeal protein replaced by HFM protein fed for 70 days. The results showed that fish growth was unaffected up to 45% fishmeal protein replacement. Dietary HFM protein could reduce the crude protein composition of body and further affect fillet quality through a significant increase in springiness, gumminess, chewiness and/or resilience. Activity of digestive enzymes (amylase, lipase and tryptase) increased as the fishmeal protein replacement increased, whereas a higher replacement level had negative impacts on absorptive capacity of intestine by decreasing its absorptive area, following by a reduction in concentration of lactate dehydrogenase, total cholesterol, high‐density lipoprotein, low‐density lipoprotein and ammonia in serum. Although intestinal antioxidant parameters were elevated by dietary HFM protein , the content of malondialdehyde in intestine was also positively associated with the protein replacement level. Overall, our results indicate that up to 45% of fishmeal protein could be replaced by HFM protein in diet without significant impact on the growth of Pengze crucian carp, whereas the crude protein content of whole body, fillet quality and oxidative status would significantly be affected when the replacement level of fishmeal protein reaches 30% together with a negative effect on the intestinal histology.     

The ecological role of bivalve shellfish aquaculture in the estuarine environment: A review with application to oyster and clam culture in West Coast (USA) estuaries

Aquaculture is viewed as a potential mechanism to meet the growing demand for seafood around the world. The future of bivalve shellfish aquaculture in the U.S. hinges on sustainable practices on the part of industry and a more consistent regulatory regime. Bivalve shellfish aquaculture is a recent practice relative to its history in other countries, beginning in the late 1800s along the U.S. West Coast where it is now well established with farm raised product utilizing land-based hatcheries and grow-out directly in numerous estuaries. Bivalve shellfish aquaculture can be viewed as a disturbance which modifies the estuarine system in three ways: 1) changes in material processes — bivalves process food and produce wastes; 2) addition of physical structure — aquaculture introduces the cultured organisms and in some cases a physical anchoring structure; and 3) pulse disturbances like harvest and bed maintenance disturb sediments, remove species in addition to the cultured organisms themselves, and change resource or habitat availability. In U.S. West Coast estuaries, water column and sediment nutrient concentrations are relatively high and influenced by large tidal exchange and proximity to deeper nearshore ocean waters where upwelling controls production during summer months. Bivalves are unlikely to influence material processes except at local bed scales in these systems, although estuary-wide effects could appear as the fraction of cultured area rises or in poorly flushed bays. Bivalve culture clearly modifies estuarine habitat at local community and at landscape scales and effects are most often evaluated against existing structured habitat in the form of submerged aquatic vegetation. Individual activities act as pulse disturbances and the recovery of eelgrass (Zostera marina) to pre-disturbance levels is variable (< 2 to > 5 years). The extent of disturbance depends on the aquaculture practice and the distribution of eelgrass reflects a balance of space competition, pulse disturbance and recovery, and is therefore at dynamic equilibrium on aquaculture beds. Structure provided by aquaculture appears functionally similar to eelgrass for small benthic infauna and mobile epibenthic fauna while use of aquaculture as habitat by larger more mobile invertebrates and fish depends on mobility and varies with life-history stage and taxon being evaluated. Scale seems a very important management consideration and further research at estuarine landscape scales, especially for habitat use by important invertebrates and fish, may prove useful in designing and implementing best management practices. Though local and short term effects from aquaculture are clearly evident in U.S. West Coast estuaries, bivalve aquaculture does not remove area from the estuary or degrade water quality like other anthropogenic influences, and thus has not been implicated in shifts to alternate states or reduced adaptive capacity of the larger ecological system.