Hatchery broodstock conditioning of the blue mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> (Linnaeus, 1758). Part II. New formulated feeds offer new perspectives to commercial hatcheries

Five diets were compared for their efficiency at maturing the gonads of the blue mussel, Mytilus edulis. The diets consisted of a 1:1:1 mixture of Isochrysis galbana (T-Iso), Pavlova lutheri, and Chaetoceros calcitrans given at concentrations of 2.4 × 10¹¹ cells day^?1 for the positive control treatment (PF) and 3.0 × 10¹⁰ cells day^?1 (=1/8) for the negative control treatment (NF). The other three treatments, MB10+, MyStock+, and Frippak+, consisted of the NF diet supplemented with one of the micro-encapsulated diets MB10 (mixture of dried algae), MyStock (formulated diet), and FRiPPAK^® Fresh #1 CAR (larval shrimp diet) at a level of 0.2% of the live weight (LW). Treatments PF, MB10+, and MyStock+ led to high percentages of spawning animals (80, 78, and 85%, respectively) and large numbers of eggs (on average 3.0 × 10⁶ eggs female^?1). Females given the NF and Frippak+ treatments produced only half the number of eggs per female, and only 17 and 6%, respectively, of the animals spawned. A high hatching rate was observed for all treatments, 71% for the pure algae diets PF and NF and more than 80% for the micro-encapsulated diets. The larvae resulting from the NF treatment were smaller, with 41% of D-larvae measuring less than 90 μm, whereas with the other treatments only 5–11% belonged to that size category. The four most important fatty acids found in mussel eggs were 16:0, 16:1(n?7), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA); these represented at least 50% of the fatty acids in all treatments. The high DHA content of MB10 and MyStock was not reflected in the fatty acid composition of the eggs whereas the high concentration of linoleic acid in MyStock was. To our knowledge, this is the first time that mussels are successfully conditioned with formulated feeds.     

水生藻类的环境指示作用(英文)

为了有效地监测水环境中的氮磷污染物、重金属、农药及其他有机污染物,笔者论述了水生藻类对水体环境中相应污染物的敏感性和耐受性,以及污染物对水域生态系统中藻类种群结构所造成的影响,分析了污染物对水生藻类的毒理和富集等。由此表明:水生藻类对一些水环境污染物具有较好的指示作用,该方法便于直观快速地调查分析相应水体的污染情况。     

大庆市主要湖泊夏季藻类植物多样性及水质评价

2010年6—8月份对大庆市35个湖泊藻类植物进行采样调查,经显微镜鉴定,共鉴定出藻类植物203个分类单位,藻类植物组成以绿藻、硅藻为主。在调查基础上,利用Shannon-Wiener多样性指数(H’)、Pielou均匀度指数(J)、Margalef等指数对各湖泊水质进行初步评价,结果显示:大庆市主要湖泊水质处于中—重度污染状态。     

Geologic composition influences distribution of microbiotic crusts in the Mojave and Colorado Deserts at the regional scale

Abiotic and biotic factors influencing distribution of microbiotic crusts within hot deserts, such as the Mojave and Colorado Deserts, are poorly known. Our objective was to examine microbiotic crust distribution with reference to soil and parent material characteristics as well as plant functional groups in wilderness areas of Joshua Tree National Park (JTNP). A total of 75 sites were visually assessed for crust abundance and plant community composition; soil physical and chemical factors also were measured. Microbiotic crusts of JTNP, in particular lichen and moss crusts, were not as well-developed or as widely distributed as in other arid regions of North America. Algal crusts were most prevalent, lichen crusts were sparse, and crusts containing mosses were rare, with average percent land surface absolute (and relative) cover for these three cover categories being 11.4% (17.4%), 1.7% (2.7%), and 0.02% (0.02%), respectively. Previously reported individual drivers of crust development, such as pH, electrical conductivity (EC), and soil texture, did not appear to strongly influence crust development in this study of the Mojave and Colorado Deserts. Proximity to granitic bedrock and grusy granitic soils associated with it were the key determinants of microbiotic crust distribution in the wilderness areas of JTNP. In particular, crusts were best developed in grusy granitic soils. Overall, our study emphasized the importance of geology in driving crust distribution and its potential value as a predictor of where crusts may occur in the hot deserts of North America.     

Effects of algae and fertilizer-nitrogen on pH, Eh and depth of aerobic soil in laboratory columns of a flooded sandy loam

 A sandy loam was incubated under floodwater in the laboratory either in the dark or in the light (7 h day, 20  °C; 17 h night, 15  °C) and with four N sources [control, ammonium carbonate [(NH₄)₂CO₃], ammonium chloride (NH₄Cl), potassium nitrate (KNO₃)]. In the dark, floodwater pH rose steadily from 6.4 to about 7.5 over 60 days in the control, KNO₃ and (NH₄)₂CO₃ treatments, but with NH₄Cl pH decreased to 5.8. In the light, algal growth began to affect the floodwater pH after 9 days. At the end of the night, pH values were similar for all treatments to those kept in the dark. During the day, pH changes depended on the morning pH value: the daily increase was zero at pH 5.6 rising to a maximum of about 2 units at pH 6.3 and falling again at higher pH values. Changes in the carbonate equilibria in response to CO₂ removal by algal photosynthesis partly explain the results, but increasing inputs of acid are also implicated below pH 6.3 possibly due to reduced volatilization and increased nitrification. Redox potential (Eh) in the floodwater was little affected by N treatment until algal growth began. Eh then decreased each day as pH rose and recovered during the night. The daily decrease in Eh per unit increase in pH rose from about 10 to 90 mV pH^–1 over the incubation period. Initially, therefore, O₂ concentration must have been increased during the day by algal photosynthesis (values <59 mV pH^–1), but later O₂ concentration must have fallen, due possibly to the decomposition of algal cells. The presence of algae initially increased the depth of the aerobic soil layer, but eventually an algal mat settled on the soil surface acting as a zone of O₂ demand as the algae decomposed. Received: 7 July 1997     

A Correlation of Rapid Cardy Meter Sap Test and ICP Spectrometry of Dry Tissue for Measuring Potassium (K+) Concentrations in Pak Choi (Brassica Rapa Chinensis Group)

Nutritional status of vegetable crops is often monitored by analysis of dried plant tissues, which is costly and often time consuming. Two greenhouse trials were conducted, at the University of Hawaii at Manoa, Magoon facilities, to evaluate the portable cardy ion meter (CIM) in determining potassium (K⁺) status in fresh petiole sap of pak choi as compared with standard laboratory methods. In the first greenhouse trial, three algae species (Gracilaria salicornia, Kappaphycus alvarezii, and Eucheuma denticulatum) were used to apply five rates of K⁺ (0, 84, 168,252, and 336 kg.ha^?1). The pak choi was directly seeded into 4 L pots and was grown in peat moss. In the second greenhouse trial, K+ was provided through Eucheuma denticulatum and potassium nitrate (KNO₃) at five rates (0,112, 168, 224, 280, and 336 kg.ha^?1) in peat moss and soil media. At harvest, K⁺ concentrations in fresh petiole sap were analyzed immediately with CIM and the dried samples were analyzed by inductively coupled plasma spectroscopy (ICP) measurement. The results showed increase in leaf K+ content at higher rates and the maximum concentration of leaf K⁺ at 4500–5300 mg/L for sap and 8–9% for tissue was obtained when K⁺ was provided between 224 and 284 kg.ha^?1. There was a close correlation between the CIM readings and the ICP method (r = 0.8048 and 0.8314) from the first and second GH results, respectively. The results suggest that the CIM could be used for the rapid monitoring of the relative K⁺ status of plants. The data further suggested 4500–5000 mg K/L for fresh petiole sap and 7.5% K⁺ in tissue as critical levels for K⁺ concentration in pak choi.     

改性粉煤灰复配物絮凝除藻的初步研究

[目的]研究混凝剂对淡水藻华的去除效果。[方法]利用低成本的粉煤灰复配磁矿粉混合物絮凝吸附水中的污染物,并通过外磁场作用将絮体移出水体,分析水体中富营养化元素的去除率并初步探讨磁性混凝剂的除藻机理。[结果]结果表明,磁性混凝剂的投加量为200 mg/L时,处理后水样中的浊度、COD、总氮和总磷含量分别下降了97.38%,78.09%,51.01%和97.08%,为最佳投加量。对处理后的水进行细胞毒性实验和藻细胞培养实验,结果显示,混凝剂处理后的水与未处理的巢湖原水细胞毒性基本一致;藻细胞培养实验证明了在处理后的水中藻类无法生存。[结论]磁性混凝剂可迅速有效地将藻类移出水体,降低水中的总氮、总磷,从根本上抑制藻华的暴发。     

高效藻类塘对小城镇养殖废水净化效能的影响

[目的]探索高效藻类塘中藻类、曝气和底泥对小城镇养殖废水净化效能的影响。[方法]设置4个独立人工池塘作对比试验,通过控制试验塘中的藻类浓度、底泥及曝气程度,测定养殖废水中的还原性物质、氮和磷的变化量,进而比较藻类、底泥和曝气对废水净化效能的影响。[结果]高效藻类塘对还原性物质、氮和磷的去除率分别达到88.3%、69.2%和59.7%,而普通塘对其去除率分别仅有48.0%、43.4%和22.8%。藻类对TP的去除影响最为明显,其次是对COD,对TN的影响最弱;曝气对COD代表的还原性物质的去除率影响最大,其次是对TN的降低,对TP的影响最弱;底泥对TP的去除影响极为显著,其次是对TN,而对COD的降低影响最弱。[结论]高效藻类塘中藻类、曝气和底泥均对养殖废水的净化产生较大影响。     

3种药剂对烟草苗床优势藻类的影响

采用乙醇法测定了3种药剂对烟草苗床藻类叶绿素含量的影响。结果表明,随施药浓度的增大抑制率呈上升趋势。在试验浓度范围内,高锰酸钾、代森锰锌对两种藻类均有较好的抑制效果,浓度大于500mg／L时,抑制率均在80％以上,三氯化铁对颤藻的抑制效果较低。     

5株溶藻抑藻细菌的筛选及果胶酶活性的初步研究

为了解决溶藻细菌分离筛选难的问题,试验以果胶为唯一碳源来分离溶藻菌,然后将分离到的菌株和试验室纯培养的铜绿微囊藻进行溶藻试验,并将溶藻效果与果胶酶活性进行比较分析,探讨细菌溶藻与细菌的果胶酶活性之间的关系。结果发现,分离到的5株细菌均具有较好的溶藻特性,试验第1天就出现菌胶膜包裹微囊藻下沉黄化的想象,5株菌具最佳溶藻效果时的菌液藻液体积比w01>w03=w05>w04>w02;达最佳降解效果的时间w05>w04>w01=w02>w03;持续抑藻时间w04>w05>w01>w02>w03;果胶酶活性w04>w01>w03>w02=w05。以果胶为唯一碳源的培养基可以有效分离到溶藻细菌,但细菌的溶藻效果与果胶酶活性之间无线性关系。