Effects of a low-radiotoxicity uranium salt(uranyl acetate) on biochemical and hematological parameters of the catfish,Clarias gariepinus

Specimens of Clarias gariepinus were treated with lethal(70,75,80,85,90,and 95 mg/L) and sub-lethal concentrations(8,12 and 16 mg/L) of uranyl acetate,a low-radiotoxicity uranium salt. The LC 50 value was registered as 81.45 mg/L. The protein and glycogen concentrations in liver and muscles were decreased in the fish exposed to sub-lethal concentrations. The red blood cell(RBC) and white blood cell(WBC) counts,haemoglobin(Hb) concentration and haematocrit(Hct) values were decreased. Different blood indices like mean corpuscular volume(MCV),mean corpuscular haemoglobin(MCH) and mean corpuscular haemoglobin concentration(MCHC) were negatively affected. Level of plasma glucose was elevated whereas protein was decreased. The level of calcium concentration(Ca) was declined in the blood of exposed fish whereas magnesium(Mg) remains unchanged. The activity level of glutamic-oxaloacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) was elevated in exposed fish. These effects were more pronounced in the last period of exposure and in higher concentrations. Results of the present study indicate that uranyl acetate has adverse effects on C larias gariepinus and causes changes in the biochemical and hematological parameters of the fish.     

Effect of hypoxia on the blood of large yellow croaker (Pseudosciaena crocea)

Large areas of hypoxic water have recently been reported in the East China Sea. It is hypothesized that hypoxia may be partially responsible for the decline of some fish stocks. We evaluated the effect of hypoxia on large yellow croaker (Pseudosciaena crocea). The fish were exposed to three concentrations of dissolved oxygen (DO; 1.5 mg/L and 2.0 mg/L, and 6.5 mg/L control). We collected blood after 6, 12, 24, 48, and 96 h exposure. There was a significant increase in red blood count, hematocrit, hemoglobin concentration, and mean corpuscular hemoglobin in the group exposed to 1.5 mg/L DO after 6 h or 12 h, and a delayed increase (only elevated after 48 h and 96 h) in these indices in the group exposed to 2.0 mg/L DO. Plasma glucose concentrations increased significantly in both hypoxic groups after 24 h. Furthermore, plasma lactate and lactate dehydrogenase activity increased significantly after the first 6 h exposure in both hypoxic groups. Our results suggest that large yellow croakers could not maintain the aerobic pathway and instead use anaerobic metabolism for survival when DO levels fall below 2.0 mg/L. We conclude that the occurrence of hypoxia (<2 mg/L DO) in the East China Sea could cause metabolic stress for large yellow croakers and may be partially responsible for the population decline of this species.     

Biochemical response of the mussel Mytilus coruscus (Mytiloida: Mytilidae) exposed to in vivo sub-lethal copper concentrations

Many aquatic organisms are negatively affected by exposure to high copper concentrations.We investigated the biochemical response of the mussel Mytilus coruscus(Mytiloida:Mytilidae) to copper exposure.In vivo bioassays using M.coruscus and different copper concentrations were conducted.The activity of six biomarkers,namely superoxide dismutase(SOD),catalase(CAT),acid phosphatase(ACP),alkaline phosphatase(AKP),glutamic-oxaloacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) were measured.Survival rates decreased with increased copper concentrations and exposure times.The LC50 values at 48,72,and 96 h exposure were 0.48,0.37,and 0.32 mg/L,respectively.Within digestive glands,CAT activity increased with increasing Cu concentrations.The activity of AKP showed no significant change,while the remaining four enzymes showed decreasing activity with increasing Cu concentrations.Within the gills,AKP activity increased when the Cu concentration was 0.05 mg/L,but showed no significant changes at higher concentrations.Activity of CAT and ACP within gills tended to decrease with increasing Cu concentration.The activity of SOD and GPT decreased at an exposure concentration of 0.2 mg/L.GOT activity within gills decreased at 0.1 mg/L and increased at an exposure concentration of 0.2 mg/L.Within the adductor muscle,AKP activity increased at 0.05 mg/L but did not change at higher exposure concentrations.ACP activity within adductor muscle tissue showed no change,while activities of CAT,GOT and GPT decreased with increasing Cu concentrations.SOD activity within the adductor muscle tissue significantly decreased at the 0.02,0.05 and 0.2 mg/L exposure concentrations.Our results show tissue specific differences for the six biomarkers in for M.coruscus.Our findings provide the basis for the establishment of reference activity levels against which biomarker changes can be estimated,and are essential preliminary steps in development of in vivo bioassays.     

Low temperature stress on the hematological parameters and <Emphasis Type="Italic">HSP</Emphasis> gene expression in the turbot <Emphasis Type="Italic">Scophthalmus maximus</Emphasis>

To study the effect of low temperature stress on hematological parameters and HSP gene expression in the turbot (Scophthalmus maximus), water temperature was lowered rapidly from 18 to 1°C. During the cooling process, three individuals were removed from culture tanks at 18, 13, 8, 5, 3, and 1°C. Blood samples and tissues were taken from each individual, hematological indices and HSP gene expression in tissues were measured. The red blood cell count, white blood cell count, and hemoglobin concentration decreased significantly (P < 0.05) as temperature decreased. Enzyme activities of plasma alanine transaminase and creatine kinase increased as temperature decreased, whereas aspartic transaminase and γ-glutamyl transpeptidase activities displayed no obvious changes above 1°C and lactate dehydrogenase activity increased first and then decreased. Blood urea nitrogen and uric acid levels were highest at 8°C, and creatinine concentration was highest at 3°C. The concentrations of plasma cortisol, cholesterol, and triglyceride all increased significantly (P < 0.05) as temperature decreased. The serum glucose concentration increased first and then decreased to the initial level. The HSP70 mRNA expression showed various patterns in different tissues, whereas HSP90 mRNA expression showed the same tendency in all tissues. Overall, these results indicate that temperature decreases in the range of 8 to 5°C may induce a stress response in S. maximus and that temperature should be kept above 8°C in the aquaculture setting to avoid damage to the fish.     

Laboratory study on the ecological impact of sophorolipid used for harmful algae elimination

We studied the role of sophorolipid in inhibiting harmful algae bloom (HAB). Different sophorolipid concentrations were tested on marine microalgae, zooplankton, fish, and bivalve (Mytilus edulis) in laboratory. The result shows that sophorolipid could inhibit the growth of algal species selectively. Among three algae species selected, Platymonas helgolandica var. tsingtaoensis was promoted with increasing sophorolipid concentration; Isochrysis galbana was inhibited seven days later in sophorolipid concentration below 40 mg/L; and Nitzschia closterium f. minutissima was inhibited obviously in only a high sophorolipid concentration over 20 mg/L. Therefore, sophorolipid in a low concentration at <20 mg/L could remove certain harmful algae species effectively without harming other non-harmful microalgae. For other animals, sophorolipid could inhibit the growth of ciliate Strombidium sp. by 50% at 20 mg/L sophorolipid concentration after 96 h. The concentration in 96-h LC₅₀ for Calanus sinicus, Neomysis awatschensis, Lateolabrax japonicus, and Paralichthys olivaceus was 15, 150, 60, and 110 mg/L, respectively. The 24 h LC₅₀ value for Artemia salina was 600 mg/L. The relative clearance rate of mussel Mytilus edulis decreased to 80%, 40%, and 20% of the control group after being exposed to 20, 50, and 100 mg/L sophorolipid for 24 h. Therefore, the toxicity for mitigation of harmful algae bloom at previously recommended concentration of 5–20 mg/L sophorolipid is low for most tested organisms in this reaserch.     

Effects of waterborne Fe(II) on juvenile turbot Scophthalmus maximus: analysis of respiratory rate, hematology and gill histology

The concentration of Fe(Ⅱ) is high in some groundwater supplies used in turbot culture,and the toxicity of waterborne Fe(Ⅱ) is unknown.We investigated the stress responses of juvenile turbot,Scophthalmus maximus,exposed to Fe(Ⅱ) of different concentrations (0.01,0.05,0.1,0.5,1,and 2 mg/L) for 1,7,14,and 28 d,under the same ambient conditions of other parameters.Changes in respiratory rate,hematological parameters,and gill structure were determined.The results show that waterborne Fe(Ⅱ) did not cause severe hematological perturbation to turbot.A low-medium Fe(Ⅱ) concentration (lower than 0.1 mg/L) could boost the respiratory rate,and caused no or very limited damage to fish.A high Fe(Ⅱ) concentration (0.1 mg/L or higher),however,caused gill damage,such as vacuoles in branchial lamellae,epithelial necrosis,and hypertrophy of epithelial cells,and even death after extended exposure time.Therefore,excess waterborne Fe(Ⅱ) and long-term exposure to Fe(Ⅱ) could be responsible for poor growth and high mortality of turbot in culture.The concentration of waterborne Fe(Ⅱ) in turbot culture should be kept below 0.1 mg/L.     

Histopathological alterations in the liver and intestine of Nile tilapia Oreochromis niloticus exposed to long-term sublethal concentrations of cadmium chloride

Fingerlings of Nile tilapia Oreochromis niloticus were exposed to 1.68, 3.36, and 5.04 mg/L cadmium(as CdCl2), which represent 10%, 20%, and 30% of their previously determined 96-h LC5 0. After exposure for 20 days, sections of the liver and intestine of treated fish were examined histologically. Histopathological changes varied from slight to severe structural modification, depending on the exposure concentration. The hepatic tissues of fish exposed to 10% LC 50 showed markedly increased vacuolation of the hepatocytes and coarse granulation of their cytoplasm. Abundant erythrocytic infiltration among the hepatocytes was observed in fish exposed to 20% LC5 0. In the intestinal tissues of fish exposed to all doses, goblet cells proliferated and were greatly increased in size, the longitudinal muscularis mucosa was disturbed and, in the crypts of the sub-mucosal layer, apoptosis increased, indicated by large numbers of degenerated nuclei. Large numbers of inflammatory cells and dilated blood vessels were observed in the intestine of the group treated with 30% LC5 0.     

Mercury distribution and accumulation in typical wetland ecosystems of Sanjiang Plain, Northeast China

Total mercury in soil,water,plant,insects,fishes and bird feathers were determined to study mercury distribution and accumulation in typical wetland ecosystems in the Sanjiang Plain,Northeast China.Results show that total mercury concentrations in soils of Deyeuxia angustifolia wetland and Carex lascarpa wetland are 0.046 mg/kg and 0.063 mg/kg,respectively.Total mercury concentration in water bodies is 0.053 μg/L on average.Of four plants studied,total mercury in moss is the highest with the mean of 0.132 mg/kg.Of 10 terrestrial insect species studied,total mercury in centipede(Scolopendra spp.) is the highest with the mean of 0.515 mg/kg while total mercury in grasshopper(Oxya spp.) bodies is the lowest.Total mercury concentrations in the herbivorous,omnivorous and predatory insects are 10.18 ng/g,16.47 ng/g and 213.35 ng/g on average,respectively.Total mercury concentrations of the adult feather(549.88 ± 63.04 ng/g),nestling feather(55.15 ± 23.53 ng/g),and eggshell(22.05 ± 5.96 ng/g) of the Grey heron(Ardea cinerea) are higher than those of the Great egret(Egretta alba)(adult feather:446.57 ± 90.89 ng/g;nestling feather:32.99 ± 17.15 ng/g;eggshell:21.02 ± 3.17 ng/g) in the wetlands of the Sanjiang Plain.The bioconcentration factors decrease in the order of piscivorous fish muscle > omnivorous fish muscle > herbivorous fish > insect.     

苯酚对奥尼罗非鱼非特异性免疫指标的影响

采用水体中常见污染物——苯酚对奥尼罗非鱼进行刺激,研究不同浓度苯酚对奥尼罗非鱼非特异性免疫功能的影响。奥尼罗非鱼分别暴露于0.005、0.025、0.125、0.625、3.125 mg/L等5个浓度的苯酚中8周,每两周采集抗凝血液和血清,用于检测非特异性免疫指标。结果表明:暴露于低浓度苯酚组(0.005 mg/L和0.025 mg/L)的奥尼罗非鱼NBT(氯化硝基四氮唑蓝)阳性细胞数等非特异性免疫指标相对于对照组无显著性差异(P>0.05),中浓度苯酚组(0.125 mg/L和0.625 mg/L)和高浓度苯酚组(3.125mg/L)对罗非鱼非特异性免疫指标的影响存在显著的时间效应和剂量效应(P<0.05),可减少NBT阳性细胞数、抑制超氧化物歧化酶活力和抗菌活力;促使溶菌酶活力和溶菌酶含量先升后降。表明中高浓度苯酚组对奥尼罗非鱼具有明显的免疫毒性。     

Use of calcein and alizarin red S for immersion marking of black rockfish Sebastes schlegelii juveniles

Black rockfi sh Sebastes schlegelii juveniles(30–40 mm total length) were immersed in a range of calcein(CAL) solutions at concentrations ranging from 50 to 250 mg/L and alizarin red S(ARS) solutions at concentrations ranging from 100 to 500 mg/L in fi ltered seawater(salinity 30) for 24 h. Fluorescent marks were detected in otoliths(sagittae, asteriscus), scales, fi n rays(dorsal, pectoral, ventral, anal, and caudal fi n rays), and fi n spines(dorsal, ventral, and anal fi n spines) after a 60-d growth experiment. With the exception of 50–100 mg/L CAL, acceptable marks were produced in the otoliths and fi n spines by all concentrations of CAL and ARS. In particular, marks were clearly visible under normal light in the sagittae, asteriscus, and fi n spines of fi sh immersed in 200–500 mg/L, 300–500 mg/L, and 200–500 mg/L ARS, respectively. Scales and fi n rays had acceptable marks at much higher concentrations(≥50 mg/L CAL, ≥300 mg/L ARS for scales and ≥50 mg/L CAL, ≥200 mg/L ARS for fi n rays). The mark quality was highest(i.e., acceptable marks were observed in all sampled structures after immersion marking) in fi sh immersed in 150–250 mg/L CAL or 300–500 mg/L ARS. In addition, there was no signifi cant difference in survival and growth of marked fi sh compared with controls 60 d post-marking( P 0.05).     

Long-term effects of di-octyl phthalate on the expression of immune-related genes in <Emphasis Type="Italic">Tegillarca granosa</Emphasis>

Di-octyl phthalate (DOP) is widely used as a plasticizer in the plastics industry. As a result, DOP is often found in marine water ecosystems where many species are exposed to it. Our objective was to evaluate the effect of long-term (14 d) DOP exposure (2.6, 7.8, or 31.2 mg/L) on the expression of immunerelated genes in Tegillarca granosa. The expression of small heat shock protein (sHSPs) and tissue inhibitor of metalloproteinase (TIMP) were highest in clams exposed to 31.2 mg/L DOP on days 7 and 14. The relative expression of Tg-ferritin, superoxide dismutase (SOD), and metallothionein (MT) increased initially then decreased as the concentration of DOP increased. The hemoglobin of T. granosa (Tg-HbI) exhibited two distinct expression patterns at two time points. Our results suggest that the immune response of T. granosa against DOP pollution varies depending on the dose. Additionally, we identified some immune-related genes that are promising candidates for biomarkers of DOP.     

A techno-economic analysis of aquaculture business in Ogun State,Nigeria

Fish supplies 25% of the total protein source in developing countries. A techno-economic analysis was performed for developing a good business proposal for aquaculture loans to enhance aquaculture development in Nigeria. A case study of catfish Clarias gariepinus framing was conducted in Abeokuta North Local Government of Ogun State, Nigeria. The results show that the fixed cost is N18 338 per year, and the variable cost is N459 700 per year, accounting for the largest amount of the total; therefore, a profit of N43 289 per month can be made. Sensitivity analysis was performed to assess any risk(s) that associated with unfavorable changes in government policy with particular reference to monetary policy. Positive net present value shows that the investment in fish farm is economically feasible and the net investment ratio is 3.52. Also, the benefit-cost ratio is 2.17. The internal rate of return (IRR) is 21% showing that the enterprise is able to offset the interest being charged on the loan. It is therefore worthwhile to invest into fish farm business in the study area. The study suggests that to better sustain the local aquaculture business, the government should create a good conducive environment to foster development of the fish farming. Government intervention is urgently needed to solve problems such as in traditional land tenure, grant credit facilities and subsidies, to enhance the aquacultural development in the country.     

丁香酚在斜带髭鲷体内蓄积与消除规律及休药期

【目的】研究丁香酚在斜带髭鲷(Hapalogenys nitens)体内的代谢特点。【方法】通过麻醉效果实验确定适宜的麻醉浓度;于15、25℃水温条件下,将斜带髭鲷在适宜浓度的丁香酚溶液中药浴麻醉8 h,转入海水中复苏;采用GC-MS/MS法测定在麻醉和复苏过程鱼体血浆、肌肉、肝脏中丁香酚浓度,依欧洲药品管理局的动物可食用组织休药期指南计算休药期。【结果与结论】用于麻醉运输斜带髭鲷的丁香酚适宜质量浓度为7.5 mg/L。药浴温度为15℃时,血浆、肌肉、肝脏达峰时间(tmax)分别为2.0、3.0、5.0 h,达峰浓度(Cmax)分别为9.82、37.58、160.07 mg/kg;药浴温度为25℃时,血浆、肌肉、肝脏tmax分别为1.5、2.0、5.0 h,Cmax分别为12.75、46.80、185.20 mg/kg。在复苏过程中,鱼体丁香酚消除符合二室模型。15℃条件下,血浆、肌肉、肝脏中丁香酚平均驻留时间MRT(0-t)分别为6.464、4.001、6.670 h;25℃条件下,MRT(0-t)分别为6.076、3.756、5.791 h。丁香酚休药期为3 d。【结论】丁香酚在斜带髭鲷体内蓄积和消除速度快,经长时间丁香酚麻醉,丁香酚在鱼体内保持长时间低浓度存在。     

Acute toxicity effects of perfluorooctane sulfonate on sperm vitality,kinematics and fertilization success in zebrafish

Perfluorooctane sulfonate(PFOS) has emerged as one of the most concerning contaminants in recent years.This study aimed to investigate the acute toxicity effect of PFOS on sperm viability,kinematics and fertilization success in zebrafish(Danio rerio).Sperm were activated in aqueous media containing a range of PFOS concentrations(0,0.09,0.9 and 9 mg/L).Viabilities and kinematics of the sperm exposed to different PFOS treatments were assessed via computer-assisted sperm analysis(CASA) at 20,40,60,and 80 s after activation.PFOS exposure decreased the percentage of motile sperm,the curvilinear velocity(VCL),and the mean angular displacement(MAD) of spermatozoa,but showed no influence on the straightline velocity(VSL) or the angular path velocity(VAP).Furthermore,a significant decrease in fertiUzation success was observed in spermatozoa that were exposed to 0.9 mg/L PFOS or more.These findings indicate that PFOS pollution in natural aquatic environment may be a potential threaten to successful reproduction offish.     

Effects of water-current speed on hematological,biochemical and immune parameters in juvenile tinfoil barb, <Emphasis Type="Italic">Barbonymus schwanenfeldii</Emphasis> (Bleeker, 1854)

This study examines the effect of water-current speed on hematological, biochemical and immune parameters in juvenile tinfoil barb (Barbonymus schwanenfeldii). Blood samples were taken on days 1, 23 and 45 from control fish and from two training groups maintained at current speeds of 0.06 bl/s (body length per second), 0.66 bl/s, and 1.92 bl/s, respectively. Significantly increased red-blood-cell counts and hematocrit were observed in the post-training groups on days 23 and 45. Significantly increased hemoglobin concentrations were also observed in the 1.92 bl/s group on days 23 and 45. In contrast, values of mean corpuscular volume were significantly lower in the 1.92 bl/s group than in the other groups on day 45. Nitroblue-tetrazolium-positive cells and lysozyme and superoxidase dismutase activities in the plasma increased significantly with increasing training intensity on days 23 and 45. Antibacterial activities were significantly increased in the trained groups compared with the control group on day 23; significantly elevated alkaline phosphatase activity was observed in the 1.92 bl/s groups on day 45. Therefore, training intensities of 0.66 and 1.92 bl/s enhanced the blood oxygen-carrying capability and plasma immune parameters of juvenile tinfoil barbs.     

Effects of heavy metals (Pb2+ and Cd2+) on the ultrastructure, growth and pigment contents of the unicellular cyanobacterium Synechocystis sp. PCC 6803

The unicellular cyanobacterium Synechocystis sp. PCC 6803, a model organism known for its unique combination of highly desirable molecular genetic, physiological and morphological characteristics, was employed in the present study. The species was cultured in BG11 liquid medium contained various initial concentrations of Pb2+ and Cd2+ (0, 0.5, 1, 2, 4, 6 and 8 mg/L). The experiment was conducted for six days and the metal induced alterations in the ultrastructure, growth and pigment contents were assessed. Alterations in the ultrastructure of the Synechocystis sp. PCC 6803 ceils became evident with the increased (>4 mg/L Pb2+) metal concentration. The photosynthetic apparatus (thylakoid membranes) were found to be the worst affected. Deteriorated or completely destroyed thylakoid membranes have made large empty spaces in the cell interior. In addition, at the highest concentration (8 mg/L pb2+), the polyphosphate granules became more prominent both in size and number. Despite the initial slight stimulations (0.2, 3.8 and 6.5% respectively at 0.5, 1 and 2 mg/L Pb2+), both metals inhibited the growth in a dose-dependent manner as incubation progressed. Pigment contents (chlorophyll a, βcarotene and phycocyanin) were also decreased with increasing metal concentration. Cells exposed to 6 mg/L Pb2+, resulted in 36.56, 37.39 and 29.34% reductions of chlorophyll a, β carotene and phycocyanin respectively over the control. Corresponding reductions for the same Cd2+concentrations were 57.83, 48.94 and 56.90%. Lethal concentration (96 h LC50) values (3.47 mg/L Cd2+ and 12.11 mg/L Pb2+) indicated that Synechocystis sp. PCC 6803 is more vulnerable to Cd2+ than Pb2+.     

广东流沙湾网箱养鱼区水体氮磷的时空变化及负荷估算

研究流沙湾网箱养鱼区水体氮、磷含量的月变化和水平分布,并运用质量平衡方程估算其氮、磷负荷。结果表明:总氮变化在0.212~0.892 mg/L之间,平均0.498 mg/L;总磷变化在0.009~0.036 mg/L之间,平均0.020mg/L;氮磷比变化在23.6~26.1之间,平均为25。在5-9月,氮、磷含量变化呈逐渐增加趋势,到9月达到最大,10月又减少。网箱内部氮、磷的含量高于网箱外部,并随着与网箱距离的增大而逐渐减小。红鳍笛鲷(Lutjanus argentimaculatus)、紫红笛鲷(Trachinotus ovatus)和卵形鲳鲹(Lutjanus erythopterus)全鱼的氮质量分数平均为2.42%,磷质量分数平均为0.26%,饵料系数为6.67,流沙湾网箱养鱼养殖期产生的氮、磷负荷平均分别为135.8和19.4 kg/t。     

Effects of heavy metals （Pb^2＋ and Cd^2＋） on the ultrastructure, growth and pigment contents of the unicellular cyanobacterium Synechocystis sp. PCC 6803

The unicellular cyanobacterium Synechocystis sp. PCC 6803, a model organism known for its unique combination of highly desirable molecular genetic, physiological and morphological characteristics, was employed in the present study. The species was cultured in BG11 liquid medium contained various initial concentrations of Pb²⁺ and Cd²⁺ (0, 0.5, 1, 2, 4, 6 and 8 mg/L). The experiment was conducted for six days and the metal induced alterations in the ultrastructure, growth and pigment contents were assessed. Alterations in the ultrastructure of the Synechocystis sp. PCC 6803 cells became evident with the increased (>4 mg/L Pb²⁺) metal concentration. The photosynthetic apparatus (thylakoid membranes) were found to be the worst affected. Deteriorated or completely destroyed thylakoid membranes have made large empty spaces in the cell interior. In addition, at the highest concentration (8 mg/L Pb²⁺), the polyphosphate granules became more prominent both in size and number. Despite the initial slight stimulations (0.2, 3.8 and 6.5% respectively at 0.5, 1 and 2 mg/L Pb²⁺), both metals inhibited the growth in a dose-dependent manner as incubation progressed. Pigment contents (chlorophyll α, β carotene and phycocyanin) were also decreased with increasing metal concentration. Cells exposed to 6 mg/L Pb²⁺, resulted in 36.56, 37.39 and 29.34% reductions of chlorophyll α, β carotene and phycocyanin respectively over the control. Corresponding reductions for the same Cd²⁺concentrations were 57.83, 48.94 and 56.90%. Lethal concentration (96 h LC₅₀) values (3.47 mg/L Cd²⁺ and 12.11 mg/L Pb²⁺) indicated that Synechocystis sp. PCC 6803 is more vulnerable to Cd²⁺ than Pb²⁺. Supported by the Chinese Scholarship Council     

The ecosystem of Lake Kenon: past and present (Transbaikal Territory,Russia)

Present-day conditions of the Lake Kenon ecosystem are determined by a combination of natural and anthropogenic factors.We have estimated the effects of a complex of factors on the condition of the abiotic environment and on specific biological components in the lake ecosystem.Change in biogenic load has caused an increase in the role of phytoplankton in the general balance of organic matter during the high-water period.Charophytes are the main dominants of bottom vegetation.Anthropogenic load has caused a decrease in both fish species and fish capacity.The lake application as a water reservoir-cooler has influenced the average annual water mineralization(from 420 mg/L to 530.0 mg/L with a maximum 654 mg/L in 1993) and fluctuations in its hydrochemical composition.The present composition of the lake is sulfate-hydrocarbonate-chloride calcium-sodic-magnesium in character.SO 4 – content is twice as much as the maximum permissible concentration in fishery waters.Water drainage from an ash disposal area to the lake has caused an increase in chemical-element concentrations including the heavy metals.Hg concentration in Perca fluviatilis muscles is 0.5 μg/g dry wt.Thus,understanding directions in the ecosystem of the water reservoir-cooler under changing hydrological conditions will let us forecast the consequences of new combined heat and power plant operation.     

维生素E醋酸酯对鱼油脂肪酸含量变化的影响

新鲜鱼油中添加05、0、2505、00 mg/kg 4种不同浓度的维生素E醋酸酯,在实验的第6、14、28、36和68天测定鱼油中的脂肪酸含量。结果表明:在500 mg/kg添加量内,维生素E醋酸酯对鱼油中脂肪酸含量没有显著性影响(P>0.05)。在实验期间,EPA(C20:5)、DHA(C22:6)、亚油酸(C18:2)含量明显下降,ARA(C20:4)、亚麻酸(C18:3)先升后降,棕榈酸(C16:1)逐步上升;C14含量逐渐增加,C17则先降后升,C16和C18在实验后期有较大提高。维生素E醋酸酯对鱼油中不饱和脂肪酸效用系数大小依次为:ARA>EPA>DHA>C18:3>0>C16:1>C18:2>C18:1,对ARA抗氧化效用最大,效用系数达到10.193%,C20:5为0.490%,C22:6为0.364%;维生素E醋酸酯对饱和脂肪酸效用系数大小依次为:C14>C17>0>C18>C16。