Viability of the marine microalga Tetraselmis suecica grown free and immobilized in alginate beads

The growth responses of free and immobolized cultures of the marine alga Tetraselmis suecica (Chlorophyta, Prasinophyceae) were compared. Algal cells were immobilized in 2% calcium alginate solution; both entrapped and free cultures were maintained in synthetic sea water at 19 salinity and 14°C constant temperature. Algal growth was evaluated by cell abundance, growth constant (K) and generation time (gt), calculated from data obtained during the exponential phase. The biomass of T. suecica, in terms of chlorophyll a content, was also determined. Cell abundance of both immobilized and free cultures was quite similar. Analysis of the T. suecica life cycle showed the higher viability of the alga after immobilization in calcium aginate gel. In addition, the mean chlorophyll a content of the immobilized cells was higher in comparison to free cells. The growth rate of the entrapped cells, on the other hand, was lower. © Rapid Science Ltd. 1998     

Cell growth, effect of filtrate and nutritive value of the tropical Prasinophyte Tetraselmis tetrathele (Butcher) at different phases of culture

A local algal isolate Tetraselmis tetrathele was studied to determine the suitable levels of three growth factors (nutrient medium, light intensity and photoperiod) for mass culture. Significantly higher population cell count (141.92 × 10⁴) were found in 4‐day‐old cultures (exponential phase) enriched with Conwy medium and exposed continuously to 93.31–103.5 μmole photon m^?2 s^?1 light intensity compared with two other media (F, SEAFDEC/AQD) under the same light conditions. Cultures exposed to higher levels of photosynthetic photon flux density and continuous photoperiod had a significantly higher cell count regardless of nutrient media used. The chemical composition of T. tetrathele varied as the culture aged. Significantly higher crude protein (49.6%) and crude ash (15.9%) were found in cultures harvested at exponential than at stationary phase of growth. In contrast, significantly higher carbohydrate (55.2%) was noted as the culture aged. There was an increase in the percentage of saturated, monoenoic and n‐3 highly unsaturated fatty acids at the stationary phase of growth. Addition of filtrate from various phases of growth and from 10‐day‐old cultures at various concentrations stimulated cell growth of T. tetrathele. This study identified the optimum growth conditions for mass culture of T. tetrathele and demonstrated its change in the chemical composition as the culture aged.     

Approach to biomass production of the marine microalga Tetraselmis suecica (kylin) butch using common garden fertilizer and soil extract as cheap nutrient supply in batch cultures

We report the possibility of an economic cultivation of the marine microalga Tetraselmis suecica, using different mixtures of a common garden fertilizer, soil extract, micronutrients and vitamins. Maximum cellular densities were obtained with a nitrogen concentration of 14 μg/ml and maximum protein concentrations were obtained with 28 μg N/ml, in all cases. The mixture of fertilizer + soil extract + micronutrients gave the best results for obtaining maximum cellular densities and protein concentrations per ml of culture. An economic evaluation showed a maximum of 2770 g of microalgal protein/dollar and 210 × 10¹² microalgal cells/dollar with the mixture of the fertilizer and soil extract.     

Sterol dynamics of heterotrophic Tetraselmis suecica and its nutritional implication in the bivalve aquaculture

Employment of heterotrophic culture of microalgal foods in the hatchery‐based seed production of oysters is still controversial because some algae produced using the method appear to loose sterols, a key nutritional factor for bivalve growth. We traced the changes in sterol content of Tetraselmis suecica growing under photoautotrophic and heterotrophic conditions with the aid of gas chromatography (GC) and GC–mass spectrometry. The photoautotrophic T. suecica at the mid‐logarithmic growth phase contained six major (cholesta‐5,22‐dien‐3β‐ol, ergost‐5‐en‐3β‐ol, cholest‐5‐en‐3β‐ol, 24‐methylcholesta‐5,22‐dien‐3β‐ol, 24‐methylcholesta‐5,24‐dien‐3β‐ol, and 24‐ethylchlolesta‐5,24‐dien‐3β‐ol) and two minor sterols (24‐methylcholesta‐5‐en‐3β‐ol and 24‐ethylchlolesta‐5en‐3β‐ol). In the comparison of algal growth and sterol level, photoautotrophic alga appeared to need higher amounts of major sterols for cell growth over heterotrophic alga. These findings, that heterotrophic alga needed less amount of sterols for growth, may have significant implications in the introduction of the method in bivalve hatcheries. We also reviewed the sterolic properties of the alga obtained from heterotrophic method with respect to bivalve aquaculture.     

Effects of dietary marine microalgae,Tetraselmis suecica,on production,gene expression,protein markers and bacterial count of Pacific white shrimp Litopenaeus vannamei

The marine flagellated Chlorophyta Tetraselmis suecica is among the most important live food species in marine aquaculture. In the present study, the effects of dietary supplementation of dried marine microalgae, Tetraselmis suecica, on growth performance; feed utilization; chemical composition; gene expression of superoxide dismutase (SOD), glutathione peroxidase (GPx) and insulin‐like growth factor 2 (IGF‐II) gene of Pacific white shrimp, Litopenaeus vannamei; muscle protein polymorphism; and microbial count were assessed and evaluated. Three hundred and sixty L. vannamei (postlarvae) Pls (0.124 ± 0.002 g) were randomly stocked into 40‐L glass aquaria (30 shrimp/aquarium) and fed three times daily four tested diets: a basal diet (control), diet incorporated with 2.5 g kg^?1 dried T. suecica (T1), 5 g kg^?1 dried T. suecica (T2) and 7.5 g kg^?1 dried T. suecica (T3) in triplicates, for 90 days. At the end of the trial, the survival rate (SR) of L. vannamei fed diets supplemented with different levels of T. suecica was significantly (p < .05) higher than the control diet. The highest weight gain and specific growth rate and the best feed conversion ratio were recorded on L. vannamei fed a diet supplemented with a 7.5 g/kg dried T. suecica. The highest protein, lipid and ash contents were obtained in L. vannamei fed the diet containing 7.5 g/kg T. suecica, when compared with the remaining tested diets. The gene expression of antioxidant genes SOD and GPx was the lowest in the T3 group in comparison with the control group. Meanwhile, expression level of IGF‐II was higher in the T2 group. The total heterotrophic bacterial count was significantly (p < .05) increased with the cumulative T. suecica level, while no significant (p > .05) differences were found in the total Vibrio count among treatments. Overall, the present results have shown that the diet supplemented with the highest inclusion level of dried T. suecica resulted in improved growth and nutrient utilization.     

Outdoor turbidostat culture of the marine microalga Tetraselmis sp.

Abstract. Biomass productivity, photosynthetic efficiency and fatty acid profiles of the marine microalga Tetraselmis sp. in a turbidostat culture system using an outdoor photobioreactor are described. The maximum productivity depended on the units in which it was expressed; it reached 5·41 × 10⁻³ g/l/h in volumetric units, and 7·26g/m²/day in surface units, the former at the smallest culture depth (0·12m) and the latter at the greatest culture depth (0·25 m). Data from the experiments were adjusted to an equation for light limitation. The comparison of fatty acid composition at both depths showed that biosynthesis of polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid (EPA), was favoured when available light was low (0·17 m). Moreover, fatty acid 16:0 seemed to be an indicator of the type of limitation in the culture, i.e. nutrient or light limitation.     

Effect of the Inclusion of Dried Tetraselmis suecica on Growth,Feed Utilization,and Fillet Composition of European Sea Bass Juveniles Fed Organic Diets

Dried Tetraselmis suecica was evaluated as a fish protein substitute when incorporated to replace (protein basis) 10% (TETRA10) and 20% (TETRA20) of the control diet. The diets were offered to nine groups of European sea bass (72 g) over 63 days. Test diets did not affect zootechnical performances nor carcass or fillet yields and proximate analysis of edible portion. Feeding TETRA20 resulted in lower apparent digestibility coefficients of protein, lipid, and organic matter, and hepatosomatic index compared to the control diet. T. suecica was able to replace up to 20% of fish protein without hampering growth performance and major quality traits of sea bass.     

Tissue distribution and cellular uptake of Aeromonas salmonicida lipopolysaccharide (LPS) in some marine fish species

Τhe uptake and distribution of lipopolysaccharide (LPS), isolated from Aeromonas salmonicida, was investigated in Atlantic cod, Gadus morhua L., turbot, Scophthalmus maximus L., and Atlantic halibut, Hippoglossus hippoglossus L. LPS was radiolabelled by bromine oxidation and subsequent sodium borotritide reduction (³H-LPS), and fluorescence-labelled by introducing a fluorescein isothiocyanate derivative (FITC-LPS). After intravenous and intraperitoneal injections in cod, high amounts of radioactive LPS (³H-LPS) were present in heart, spleen and kidney throughout the experimental period (1–168 h). After peroral administration, a high amount of ³H-LPS was observed in intestinal tissues, whereas internal organs and tissues contained considerably lower amounts. Following intravenous administration of ³H-LPS in turbot, high contents of radioactivity were revealed in spleen, liver and kidney, whereas the content in heart was lower than in blood at the sampling times (1–24 h). The same pattern was observed after intraperitoneal administration. The spleen and liver contained high amounts of radioactivity when the turbots were intubated perorally with ³H-LPS. The spleen, kidney and heart were the main scavenging organs following intravenous administration of ³H-LPS in Atlantic halibut. A minor amount of radioactivity was present in the liver. The same pattern emerged after intraperitoneal injection in halibut. As observed for turbot, the spleen was the main accumulation site for ³H-LPS following peroral administration. Fluorescence microscopy of sections of organs and tissues from cod, intravenously and intraperitoneally injected with FITC-LPS, revealed that endocardial cells of both atrium and ventricle contained large amounts of the fluorochrome, whereas in turbot and halibut only atrial endothelial cells accumulated the substance. In all species, macrophages in kidney and spleen contained FITC-LPS and in the spleen the fluorochrome was trapped in the ellipsoidal walls. At later time points (e.g. 48 h) in the turbot spleen, FITC-LPS was located in cells adjacent to the ellipsoidal walls. Halibut endothelial cells that were located in the connective tissue of the intestine and gills also contained FITC-LPS. After peroral administration to the different fish species, specific fluorescence was found only in intestinal epithelial cells of halibut and in cells located in the lamina propria. Fluorescence was not detected in internal organs such as the kidney, spleen and liver after peroral administration of FITC-LPS. Gel chromatographic analysis of plasma samples from cod, turbot and halibut after intravenous and intraperitoneal injections showed that high molecular weight radioactivity was present. A minor amount of radioactivity that corresponded to low molecular weight substances was also observed. In conclusion, there is a high degree of variation with respect to the site of accumulation and some variation in the type of cells involved in the uptake of purified LPS in cod, turbot and halibut.     

Nutritional values of Apocyclops dengizicus (Copepoda: Cyclopoida) fed Chaetocerous calcitrans and Tetraselmis tetrathele

The cyclopoid copepod Apocyclops dengizicus was isolated from a marine shrimp pond, Penaeus monodon, Kuala Selangor, Malaysia, and reared in the laboratory for 3 months to establish a pure population stock. Amino acids and fatty acids of A. dengizicus were determined when fed Chaetocerous calcitrans (C), Tetraselmis tetrathele (T) and their combination (CT) (1:1 by number). The protein contents in A. dengizicus that received C, T and CT were 46.8%, 60.5% and 55.3% of dry weight respectively. Correspondingly, the lipid was 19.0%, 17.8% and 19.1% of dry weight for C, T and CT respectively. The A. dengizicus cultured on C, T and CT had total essential amino acids without tryptophan measurement of 57.1, 60.3 and 67.8 and total non‐essential amino acids of 42.9%, 40.0% and 32.2% of total amino acids. The fatty acid content of A. dengizicus showed that it was able to synthesize docosahexenoic acid (22:6n‐3, DHA), eicosapentaenoic acid (20:5n‐3, EPA) and arachidonic acid (20: 4n‐6, ARA) from examined microalgal diets. The DHA:EPA:ARA ratios of A. dengizicus fed on C, T and CT were 6.8:3.0:1, 14.0:5.8:1 and 11.6:2.6:1 respectively. Apocyclops dengizicus could be suitable live food for larval fish and shrimp rearing because it meets their nutritive requirements.     

Influence of the marine abundance of pink (Oncorhynchus gorbuscha) and sockeye salmon (O. nerka) on growth of Ozernaya River sockeye

The length and weight of Russian sockeye ( Oncorhynchus nerka ) returning to the Ozernaya River (Kamchatka) was substantially reduced in years when the ocean abundances of Kamchatkan pink ( O. gorbuscha ) and sockeye salmon were high. We found that the density-dependent reduction in sockeye growth on a per-capita basis was greater for sockeye than for pink salmon. However, the overall effect of pink salmon abundance on sockeye growth was greater because of the higher numerical abundance of pink salmon. The strongest statistical relationships were found for sockeye from separate age groups; pooled data combining all age classes were statistically insignificant. We estimate that, if pink salmon were absent, the most strongly affected age group of sockeye salmon (2.1 males) would weigh twice as much at maturity than if pink salmon populations from eastern and western Kamchatka were both simultaneously at peak observed abundances. Trophic competition in the ocean between pink and sockeye salmon can therefore have a significant influence on the productivity of sockeye populations for the most strongly affected age groups. These effects are large enough that they should be explicitly considered in the management of salmon populations.     

三种大型海藻吸收营养盐的动力学研究

研究大型海藻孔石莼(Ulva pertusa)、条浒苔(Enteromorpha clathrata)和巨角叉菜(Chondrus nipponicus)对氨氮、硝酸态氮和磷酸盐磷的静态吸收动力学。三种海藻对氨氮的吸收可用一级动力学方程描述,孔石莼、条浒苔和巨角叉菜的吸收速率常数分别为:0.244/h(R2=0.992)、0.124/h(R2=0.962)、0.096/h(R2=0.951)。孔石莼和条浒苔对氨氮的吸收分快速、平稳和缓慢吸收3个阶段,而巨角叉菜对氨氮的吸收开始较慢,随后加快,最后缓慢;三种海藻吸收硝酸态氮规律相似,可用一级动力学方程描述。巨角叉菜对硝酸态氮吸收最好,条浒苔则吸收不理想。三种海藻对硝酸态氮的吸收速率远低于氨氮。孔石莼和巨角叉菜对磷酸盐磷有吸收,孔石莼的吸收速率高于巨角叉菜,条浒苔对磷酸盐磷吸收不明显。     

Biological evaluation of phytoplankton (Chlorella sp., Tetraselmis sp. and Isochrysis galbana) as food for milkfish (Chanos chanos) fry

Phytoplankton cultures of Chlorella sp., Tetraselmis sp. and Isochrysis galbana were used alone as feed to rear separate batches of newly caught milkfish (Chanos chanos) fry (about 21 days old). Ultrastructural studies of fry hepatocytes and pancreatic acinar cells indicated that they cannot directly utilize Chlorella, which has a rigid cell wall. The fry can directly utilize Tetraselmis and Isochrysis, but neither is nutritionally adequate for growth and survival if used as the only feed. Tetraselmis is nutritionally inferior to Isochrysis.     

pH和氮磷比对微小原甲藻和青岛大扁藻生长竞争的影响

为探讨pH和氮磷比对青岛大扁藻(Tetraselmis helgolandica)和微小原甲藻(Prorocentrum minimum)生长竞争的影响,本研究首先根据对虾养殖水体pH值的范围设置了7.5,8.0,8.5和9.0共4个pH梯度,获得了青岛大扁藻抑制微小原甲藻的最佳pH;在该pH条件下,设置了氮磷比分别为3:2(高富磷组),6:1(富磷组),24:1(对照组)和96:1(富氮组)等4个梯度,其中,单种培养体系中只接种青岛大扁藻或者微小原甲藻,混合培养体系中同时按照1:1的比例接种青岛大扁藻和微小原甲藻。结果表明,混合培养体系中,青岛大扁藻在pH 8.5和pH 9.0时,出现拐点时间最晚,均为7 d;而微小原甲藻在pH 8.5和pH 9.0时,出现拐点时间最早,均为3 d。pH 8.5时青岛大扁藻对微小原甲藻的竞争抑制参数最大,青岛大扁藻抑制微小原甲藻的最佳pH为8.5。单种培养体系中,微小原甲藻拐点出现的时间在高富磷组、对照组和富氮组中均晚于青岛大扁藻;混合培养体系中,对照组中微小原甲藻和青岛大扁藻拐点出现时间分别为4 d和3 d,而其他处理组2种微藻拐点出现的时间分别相同。氮磷比影响混合培养中2种微藻的竞争抑制参数,其中,96:1(富氮组)中拐点之后青岛大扁藻对微小原甲藻的竞争抑制参数(α)的平均值为9.2063,微小原甲藻对青岛大扁藻的竞争抑制参数(β)为3.4886。以上研究表明,对虾养殖水体中,青岛大扁藻抑制微小原甲藻的最佳条件是:pH为8.5,氮磷比为96:1。     

聚苯乙烯微塑料长期暴露对海水青鳉 (Oryzias melastigma) 亲代生长、繁殖及子代发育的影响

海水青鳉 (Oryzias melastigma) 作为雌雄异体的模式动物,在研究外来污染物毒性效应性别差异上具有优势。运用转录组学技术系统研究了雌、雄海水青鳉肝脏组织中的差异表达基因,结果显示雌、雄青鳉肝脏中共有1 351个显著差异表达基因,其中683个在雌鱼肝脏中高表达,668个在雄鱼肝脏中高表达。雌鱼肝脏中高表达的差异基因主要涉及生殖和性激素合成相关通路,如卵黄蛋白原和雌激素受体。雄鱼肝脏中高表达的差异基因主要涉及能量代谢、细胞骨架和肌肉收缩等相关生物过程,如丙酮酸激酶、肌酸激酶、肌球蛋白和肌钙蛋白等。实时荧光定量PCR验证结果显示,除DNA错配修复蛋白基因以外,其他17个基因差异表达倍数与RNA-seq对应基因差异表达趋势基本一致,表明转录组分析数据基本可靠。研究表明,雌、雄海水青鳉肝脏中基因表达具有差异调控模式,研究获得的差异基因和调控通路将为海水青鳉对外来污染物性别差异响应分子机制研究提供一定的理论基础。     

The behaviour of the microalgae Tetraselmis chuii in cadmium-contaminated solutions

The accumulation of cadmium by living and dead cells of the green microalgae Tetraselmis chuii was studied both in cell suspensions and in growing conditions. Microalgal cell suspensions accumulated a maximum of 292.60 (23.09) and 210.54 (16.05) mg Cd (g biomass)-1 when living and dried cells were used, respectively. After biosorption, the total cadmium accumulated was efficiently desorbed with concentrated EDTA solution, indicating that cadmium accumulation took place through surface structural components. During cell growth in cadmium-contaminated medium, the toxic effect of the metal proved to be higher for increasing metal concentrations in the medium. This increasing toxicity had a marked influence upon cell productivity. Cadmium was not incorporated during growth of T. chuii cells.     

海洋环境变化对北太平洋柔鱼个体生长的影响

海洋环境变化会对海洋生物个体大小及其生长产生影响,特别是短生命周期的种类.为此根据2009—2012、2015—2016年8—10月采集的6091尾北太平洋柔鱼样本,对其渔业生物学特征进行了研究,并分析海洋环境因子对其个体生长的影响.结果显示,雌雄个体生物学特征在不同海洋环境年均存在显著差异.柔鱼胴长与太平洋年代际涛动...     

Effect of marine Eubothrium sp. (Cestoda: Pseudophyllidea) on the growth of Atlantic salmon, Salmo salar L.

Atlantic Salmon, Salmo salar L., experimentally infected with marine Eubothrium sp. were kept together with uninfected salmon in the laboratory for 11 months in two tanks, 80 infected and 80 uninfected in each tank. The infected fish had a reduced growth rate compared with the uninfected fish. Significant differences in growth between infected and uninfected fish were not observed until several months post-infection. There was no correlation between the number of Eubothrium sp. and fish weight, indicating that even low intensity alters the growth rate of the salmon. The cestode had the same effect on both sexes of salmon. Haematocrit level was found to be significantly lower in infected compared with uninfected salmon in one of the samples during the experiment.