Inhibition of embryo development of the Mytilus galloprovincialis marine mussel by organic pollutants; assessment of risk for its extensive culture in the Galician Rias

This study evaluates the risk posed by selected organic pollutants on the culture of the marine mussel in the Galician coast (NW Iberian Peninsula), which depends on collection of natural seed in densely populated coastal areas. With this aim toxicity tests were carried out with embryos of the Mytilus galloprovincialis mussel, and the toxicity of the surfactant sodium dodecyl sulphate (SDS) and the biocides TBT, chlorpyrifos and lindane was quantified in terms of median effective concentration (EC₅₀) and toxicity threshold (EC₁₀ and LOEC), using embryogenesis success as end point. The EC₁₀ and EC₅₀ values were 161 and 377 ng/L for TBT, 79 and 154 µg/L for chlorpyrifos, 495 and 2353 µg/L for SDS, 1.41 and 1.99 mg/L for lindane. Toxicity thresholds for mussel embryos from this study and crustacean larvae from the literature were compared to environmental concentrations in coastal waters, either directly measured or estimated from mussel bioaccumulation data, in an attempt to evaluate the risk posed by those pollutants to these commercial species. It was concluded that SDS and, especially, chlorpyrifos and lindane, do not pose a threat to these commercial resources. In contrast, TBT risk quotients derived either from actual seawater measurements or mussel bioaccumulation data were both unacceptably high. TBT pollution represents thus a potential threat to natural availability of spat, the basis of extensive mussel culture. At the light of the data presented, current TBT seawater quality criterion seems underprotective and it should be revised.     

Replacement of living microalgae with spray-dried diets for the marine mussel Mytilus galloprovincialis

Growth experiments were carried out in which juvenile mussels Mytilus galloprovincialis were fed diets composed of spray-dried algal products (Sanders Brine Shrimp) which included Schizochytrium sp. (SZ; Docosa Gold), Spirulina platensis (Sp) [=Arthrospira platensis] and Hematococcus pluvialis (H) either alone or in combination with partial rations of living microalgae. Growth of mussels fed 1/4 ration of living algae plus a mixed supplement of 50/50% w/w SZ:Sp grew significantly (SNK; P<0.05) faster than mussels fed a full live algal ration. Furthermore, growth (both wet weight and dry organic weight increase) of mussels fed diets composed of either 70/30% w/w SZ: ground Sp (GSp; <20 μm) or 25/50/25% w/w H:SZ:GSp was significantly (PLSD; P<0.05) greater than that of mussels fed an equal ration (by dry weight) of living Tahitian Isochrysis galbana.     

厚壳贻贝胚胎和早期幼虫神经系统发育的初步研究

采用免疫细胞化学技术和荧光染色技术初步研究了厚壳贻贝胚胎及早期幼虫的神经发育情况以及含有不同类型神经细胞的时空分布.在厚壳贻贝从受精开始至囊胚期的整个胚胎发育过程中,均未发现FMRF酰胺类免疫阳性信号和5-羟色胺免疫阳性信号,神经最初形成于担轮幼虫阶段,出现了FMRF酰胺类免疫阳性信号和5-羟色胺免疫阳性信号,36 hpf时,更多的FMRF酰胺类免疫阳性信号出现在幼虫顶部区域左右两侧,伸出的阳性纤维延伸后形成基底神经纤维,并延伸至正在发育的中足所在区域.在顶端区所有阳性信号中,第一个免疫信号始终处于腹部,位置未发生变化.D形幼虫阶段神经系统的FMRF酰胺类免疫阳性信号分别是顶器官的3个顶部阳性信号、侧部2个阳性信号以及足区形成的2个阳性信号.顶器官中的信号延伸出免疫活性纤维形成基底神经纤维.18 hpf时,第1个5-羟色胺免疫阳性信号出现在早期担轮幼虫的顶器官前端.在早期D形幼虫阶段,阳性信号伸出一个短小的基底神经纤维,并延伸至后来发育成的顶器官神经纤维网部位,42 hpf时,更多5-羟色胺阳性信号细胞出现在顶区域,数量增至2～3个.D形幼虫阶段(48 hpf),5-羟色胺免疫阳性信号数量增至4个,分布于脑神经节的周围,其发出的基底纤维延伸至紧密的顶神经纤维网.     

Evaluation of electrical stunning of sea bass (Dicentrarchus labrax) in seawater and killing by chilling: welfare aspects, product quality and possibilities for implementation

The objective was to assess neural, behavioural responses and product quality in farmed sea bass (Dicentrarchus labrax) upon electrical stunning in seawater. The electrical sinusoidal 50 Hz or pulse square wave alternating 133 Hz current induced a general epileptiform insult with a current of 3.3±0.2 or 3 A dm^?2, respectively, for 1 s head to tail in seawater. The total duration of the insult was 48±34 and 23±11 s. After stunning, the electro‐cardiogram revealed fibrillation and ceased or showed malfunction. Product quality was assessed in a group electrically stunned, followed by chilling in ice water and the controls were only chilled in ice water. The pH of the fillets was 0.1–0.2 lower (P<0.01) when stunned electrically at days 1, 2, 8 and 10 postmortem, where the colour did not differ. The percentage of sea bass effectively stunned using an electrical sinusoidal or pulse square wave current was above 85% within a confidence level of 95%. A combination of electrical stunning for 10 s, followed by chilling in seawater with ice flakes resulted in the death of all fish. The former method is recommended to be adapted for implementation in practice.     

配合饲料和冰鱼对单体养殖中华绒螯蟹生长、性腺发育及其肌肉品质的影响

为研究配合饲料和冰鱼对中华绒螯蟹的养殖性能和营养状况的影响,本实验通过连续采样分析了单体养殖中华绒螯蟹的生长性能、性腺发育和肌肉的营养成分,并进一步比较了终末体质量、增重率、特定增长率、成活率和蜕壳间隔.结果 显示:①配合饲料组的成活率极显著高于冰鱼组,而终末体质量、增重率、特定增长率和蜕壳间隔二组无显著差异;在不同蜕...     

Plant‐associated invertebrates and ecological quality in some Mediterranean shallow lakes: implications for the application of the EC Water Framework Directive

• 1. The EC Water Framework Directive requires that Member States assess the ecological quality of their water bodies on the basis of a wide set of variables, including benthic invertebrates.
• 2. The aim of the study was to find one or more faunistic indices that could be related to ecological status of shallow lakes, independent of different macrophyte types.
• 3. Six invertebrate indices were calculated from abundance and biomass data in 10 Spanish shallow lakes: total abundance and biomass, Shannon's index, percentage of predators, percentage of Ephemeroptera, Plecoptera and Trichoptera, Orthocladiinae as a percentage of the total Chironomidae, and Chironominae as a percentage of the whole macroinvertebrate community. Taxon richness was also calculated.
• 4. Differences in the values of indices across different macrophyte types were explored by means of a one‐way analysis of variance. Significant differences were occasionally found when indices were calculated from biomass data. Total abundance was also significantly different across some architecture types.
• 5. No significant correlations were found between the overall values of the indices for each lake and the environmental variables measured (ecological status, total nitrogen, total phosphorus, chlorophyll a concentrations, dynamics of the water flow, and naturalness of the shore), except in the case of total biomass.
• 6. Values of indices were plotted (box plots) to detect potential differences between lakes of different ecological status. None of the index values was clearly related to ecological status. Thus, the approach used here, requiring relatively little sampling effort and taxonomic expertise, was of little use as a quality indicator for shallow lakes. The implementation of the Directive will therefore require different approaches to be developed and tested.

Copyright © 2004 John Wiley & Sons, Ltd.     

The effects of the decomposition of mangrove leaf litter on water quality, growth and survival of black tiger shrimp (Penaeus monodon Fabricius, 1798)

An experiment was conducted for 8 weeks at the Cantho University, Vietnam, to determine the acceptable level of mangrove leaf litter load and its effect on water quality, growth and survival rate of tiger shrimp (Penaeus monodon). Shrimps were cultured in plastic tanks containing 50 L of brackish water (salinity of 15‰). Leaf litter of Rhizophora apiculata, Avicennia officinalis, Excoecaria agallocha and Acacia auriculiformis were loaded to tanks at rates of 0.0 (control), 0.125, 0.25, 0.5, 1.0 and 2.0 g L^− 1 with and without aeration. Tiger shrimp post-larvae (PL; 0.05 ± 0.01 g) obtained from the shrimp hatchery of Cantho University were stocked at a density of 20 PL per tank and fed with pelleted feed containing 38% protein at a rate of 10% body weight (BW) day^− 1.

The high leaf-loading rates significantly reduced dissolved oxygen (DO) and survival rates of shrimp in the non-aerated treatments, and all shrimps died after 2 days in the treatments with loading rates above 0.5 g L^− 1. Leaf litter loads significantly increased tannin content, chemical oxygen demand (COD), H₂S and pH in the aerated treatments. Stepwise regression analysis showed COD, tannin and H₂S concentrations had negative effects on shrimp growth in the aerated treatments. Tannin concentration was found to be highest in the treatments with Excoecaria (32 mg L^− 1) and Avicennia (24 mg L^− 1) leaves. However, there were no significant differences in growth and survival rates of shrimp among the aerobic treatments loaded with different leaf types. The results of this study showed that moderate load of mangrove leaves could play an important role in promoting shrimp growth and survival in aerobic condition. Mangrove leaves at a loading rate of 1 g L^− 1 positively influenced both the survival and growth rate of shrimps.     

Comparison of the effects of six stunning/killing procedures on flesh quality of sea bass (Dicentrarchus labrax,Linnaeus 1758) and evaluation of clove oil anaesthesia followed by chilling on ice/water slurry for potential implementation in aquaculture

The effects of different stunning/killing procedures on flesh quality of European sea bass were investigated: (1) anaesthesia with clove oil, (2) anaesthesia with 2‐phenoxyethanol, (3) percussive stunning, (4) immersion in ice/water slurry, (5) chilling on ice and (6) anaesthesia with clove oil followed by immersion in ice/water slurry. Muscle pH values were significantly lower in sea bass anaesthetized or stunned by a blow to the head compared with fish immersed in ice/water slurry, chilled on ice or immersed in ice/water slurry after clove oil anaesthesia. Lightness was highest in sea bass anaesthetized by 2‐phenoxyethanol or percussively stunned and lowest in ice‐chilled fish. Redness and yellowness were highest in fish chilled on ice and lowest in fish anaesthetized with clove oil. Liquid loss, fat loss and shear values were not significantly different among the procedures. In general, lipid oxidation values during refrigerated or frozen storage did not significantly differ among treatment groups. Combination of clove oil anaesthesia followed by chilling on ice/water slurry appears to improve both flesh quality and welfare of sea bass, although the implementation of further studies is warranted to consolidate this finding.     

A stochastic approach for analysis of the influence of white spot disease, zootechnical parameters, water quality, and management factors on the variability of production of shrimp Litopenaeus vannamei cultivated under intensive commercial conditions

We investigated the variability of shrimp Litopenaeus vannamei production by incorporating stochastic elements into deterministic stock models and determined the contribution that white spot disease, zootechnical parameters, water quality, and alternative management strategies have on variability. The model was calibrated for intensive shrimp cultivation in the State of Nayarit, Mexico. Mean annual production increased as a consequence of improved management from 8000 kg ha⁻¹ to 22,000 kg ha⁻¹ when cultivation was not affected by the disease and from 3200 kg ha⁻¹ to 10,400 kg ha⁻¹ when the disease affected production. When simultaneously considering both cases, mean annual production increased from 6300 kg ha⁻¹ to 16,800 kg ha⁻¹. White spot disease was a major factor determining variability of production. Shrimp production was particularly sensitive to levels of dissolved oxygen when management was inadequate, while final weight and mortality rate of shrimp were more sensitive when management improved. Water temperature and salinity had intermediate importance, and mortality caused by the disease and the time when mortality occurred had intermediate or low relevance. Improving management increased shrimp production and diminished variability. The duration of cultivation and stocking density were the most important management variables controlling variability of production when cultivation was affected by the white spot disease. When the disease was not present, pond size and duration of cultivation were the main factors affecting production. Starting time of aeration had relatively lower importance in determining variability, while the stochastic values of dissolved oxygen, in contrast, became most important. These results call for studies on improving aeration management to reduce variability of dissolved oxygen in ponds.     

Dynamic stock model for analysing semi‐intensive production of whiteleg shrimp Litopenaeus (Penaeus) vannamei affected by the acute hepatopancreatic necrosis disease: Assessment of disease severity indicators and relationships with pond water quality parameters

The production of Litopenaeus vannamei was analysed when affected by the acute hepatopancreatic necrosis disease using a dynamic stock model and primary data of seven production cycles from a shrimp farm in Mexico from 2013 to 2016. Significant results (p < .05) of the correlation analysis indicated that during those years mortalities by the disease were more severe when water salinity was high and productivity was low. Significant results from ANOVA showed that throughout the period, disease severity and salinity diminished while pond productivity initially declined but subsequently improved. Significant results from regression analyses conducted for each production cycle also indicated the importance of salinity and productivity on disease severity and showed that early mortality by the disease occurred in ponds with warmer water. Within the observed range of water quality parameters, increases of 1 cm in water transparency and 1 g/L in salinity resulted in increments within 0.17%–0.25% and 1.7%–3.1% in shrimp mortality by the disease. When increases of 1°C in water temperature were recorded, outbreaks occurred 0.2–1.57 weeks earlier. In conclusion, the disease strongly determines the dynamics of shrimp production, and the role of salinity, productivity and temperature is worthy of further delving.     

壳白长牡蛎基因型与环境互作(G×E)效应分析

为探索壳白长牡蛎品系的壳色性状和生长性状的基因型与环境互作(G×E)效应,利用巢氏设计构建全同胞家系,每个家系分成两组分别在乳山和荣成海域进行养殖。利用线性混合模型和REML法分析11月龄壳白长牡蛎生长性状和壳色性状的遗传力及G×E效应。采用最佳线性无偏预测法(BLUP法)估计壳高和L~*两个性状的育种值,并通过加权获得综合育种值来筛选优良家系。结果显示,乳山组和荣成组的壳白长牡蛎生长和壳色性状的遗传力不同,分别为(0.14±0.08)～(0.62±0.18)和(0.01±0.03)～(0.78±0.19),可能存在尺度效应。以不同环境为固定效应,综合两个环境计算出的生长和壳色性状的遗传力为(0.02±0.02)～(0.51±0.09),然而由于部分全同胞家系缺失和模型不收敛的原因,估计模型中未包括母本/共同环境效应和显性效应,上述遗传力估计值偏高。本研究中生长和壳色性状在两个环境间的遗传相关为(–0.47±0.40)～(0.75±0.18),均小于0.8,表明壳白长牡蛎品系的生长和壳色性状都具有明显的重排效应,壳白长牡蛎品系其选育需要针对不同的养殖环境培育不同适应性的选育家系。综合育种值排名前20的个体其家系来源比例表明,家系G1和G21对于乳山海域表现出特殊的适应性,而家系G4、G22和G5对荣成海域环境具有特适性,家系G2则对两个环境具有普适性。研究为壳白长牡蛎品系的良种选育提供了重要的参考依据。