Assessment of diet and temperature on the overall performance of Patagonian red octopus (Enteroctopus megalocyathus,Gould) paralarvae

The limitation to sustain the Patagonian red octopus Enteroctopus megalocyathus aquaculture is the lack of an efficient diet to obtain high survival during the paralarvae stage. This work has studied the performance of paralarvae under different combinations of feeds and temperatures using a factorial design. The diets were based on various Artemia enrichments: (a) Nannochloropsis sp, (b) Ori‐gold (Skretting) and (c) LC60 (Phosphotek). The temperatures chosen were in accordance with those found in their environment: 10°C (winter), 12°C (spring–autumn) and 14°C (summer), by triplicate. The factorial combinations were tested in two experiments with paralarvae of different age: Exp 1, from newly hatched to 14 days after hatching (DAH), and Exp 2, from that point to 42 DAH. It was concluded that temperature was the primary variable affecting mortality, feed intake, relative weight condition index, morphometric variables and trypsin activity. The enriched Artemia diets had the main impact on the leucine‐aminopeptidase activity, and on the fatty acid contents, mainly 20:5n‐3 (EPA) and 22:6n‐3 (DHA). Paralarval growth was increased by temperature with only one diet and at a certain age. Nutritional requirements varied between early and late paralarvae, and the possibility of changing the diets according to the development age is discussed.     

黑龙江省哈大高速公路中央分隔带绿化树种调查与选择

对哈尔滨至大庆间高速公路现有景观绿化植物种类及中央分隔带立地条件进行实地调查与分析。该路段景观绿化植物6种,其中常绿乔木2种,花灌木4种,植物种类单调,彩化树种缺乏。中央分隔带土层薄,呈中性或偏酸性,土壤速效氮、速效钾和速效磷含量低,土质较差。根据植物的生态学特性及路段的现有条件,结合高速公路绿化要求的特殊性,探讨哈大高速公路中央分隔带绿化树种的选择,为黑龙江省高速公路景观绿化植物的选择、设计、施工和更新改造提供科学依据。     

油菜无菌苗最佳生长条件的探讨

以甘蓝型油菜种子作为试验材料,对无菌苗培养前的种子消毒剂种类及不同消毒时间、浓度等的消毒效果进行了比较研究;对影响无菌苗生长的培养基配方、pH值及生长时间等因素进行了探讨。结果表明:油菜无菌苗的最佳生长条件为:70%酒精表面消毒1~2 min后,用15%H2O2消毒35 min,无菌水冲洗3~5次,无菌水浸泡种4~15 h,接种至1/2 MS培养基 20 g/L蔗糖 7.5 g/L琼脂,pH值为5.8,25℃,生长4~6 d即可作为转基因用无菌苗。     

人工诱导下观赏植物的阶段转变类型及幼年期的确定

花期调控需要有效的人工诱导。在植物的幼年期,任何诱导都是无效的,因此,需要确定结束其的时间。本文对用于判断幼年期的量化指标、判断准则和常规步骤等进行了总结,确定了常用的标准。被诱导的阶段转变指的是人工诱导下植物从幼年期向成熟期的转变过程。本文归纳出五种被诱导的阶段转变的基本类型,对每种类型的特征进行了描述和举例,确定了幼年期结束的判断方法,讨论了影响判断的因子及长期存在的争议。     

四川省麻疯树适生区划分

通过对四川省麻疯树生态适生条件需求的分析,确定四川省麻疯树适生区划分的主要指标和区划标准,并通过立地条件选择区划出四川省麻疯树栽植适生区.     

On condition index and percentage edibiliy of the shortneck clam Paphia malabarica (Chemintz) from estuarine regions of Ratnagiri,west coast of India

Paphia malabarica is an important clam species, which has formed vast beds in the Kalbadevi estuary (Shirgaon creek) and Kajali estuary (Bhatye creek), Ratnagiri. They are exploited here commercially throughout the year for local as well as external markets due to the heavy demand. This study was undertaken to assess seasonal variations in the quality of the meat of clams by estimating the condition index and percentage edibility. Higher values were recorded during the monsoon (June–August). A rapid decline was observed in the edibility values from November onwards. Higher condition index and percentage edibility were recorded from June to November, indicating the high quality of clam meat.     

Seasonal variation in the condition index of Pacific oyster postlarvae (Crassostrea gigas) in a land‐based nursery in Sonora,Mexico

This study examined the seasonal variation in the condition index (CI) of Crassostrea gigas postlarvae (<5 mm) that were cultivated at a commercial hatchery. Oysters were sampled weekly at the nursery using seawater from a lagoon for the grow‐out that precedes commercialization. Temperature, salinity, seston, chlorophyll a, oxygen and pH were recorded at each sampling and water samples were taken to identify phytoplankton groups and their abundance. High levels of primary productivity, chlorophyll a and seston were detected during summer, but the highest CI occurred in winter. During winter, elevated phytoplankton biomass was composed by diatoms and phytoflagellates, which served as the main food source and promoted weight gain in this season. Variations in salinity, oxygen and pH were not related to differences in the CI. However, it appears that the wide temperature variation affected functions, such as feeding activity, apparently enhancing ingestion during winter (mean 16.5±1.4 °C) and reducing ingestion during summer (mean 31±1.5 °C). Winter production resulted in postlarvae with a homogeneous size range and a high CI, indicating that winter is more favourable to start cultivation. The CI represents a practical means to determine the physiological state of postlarvae before transfer to cultivation sites.     

二种槭树有效获得无菌试管苗的研究

以挪威槭的成熟种子,自由人槭的顶芽、幼嫩茎段为外植体,研究了0.1%升汞不同消毒时间、不同培养条件、不同培养基对2种槭树有效获得无菌试管苗的影响.结果表明:挪威槭种子用0.1%升汞消毒8 min,在Ms+6-BA 0.5 mg/L+NAA 0.2 mg//L的培养基上,黑暗条件、温度24～26℃下,有效的获得了无菌试管苗;自由人槭以顶芽为外植体,0.1%升汞消毒6min,在MS+6-BA 0.5(0.2)mg/L+NAA 0.2 mg/L培养基上,光照3 000 5 000 lx、温度24～26℃下,同样有效的获得了无菌试管苗.     

Adaptive management of stocking rates to reduce effects of drought on cow-calf production systems in semi-arid rangelands

We used simple ecological sustainability simulator (SESS) [Díaz-Solís, H., Kothmann, M.M., Hamilton, W.T., Grant, W.E., 2003. A simple ecological sustainability simulator (SESS) for stocking rate management on semi-arid grazinglands. Agric. Syst. 76, 655–680. <http://dx.doi.org/10.1016/j.agsy.2005.07.008>], modified to represent each of five management strategies (sets of decision rules) for adjusting stocking rates, to identify strategies that could reduce effects of drought on cow-calf production systems in semi-arid rangelands. We parameterized the model to represent a region of extensive cow-calf production in the northeastern portion of the Mexican state of Coahuila, and evaluated animal performance (animal body condition, cow mortality, and calf production) and range condition resulting from each strategy under random precipitation conditions typical of the region. To evaluate the validity of the randomly generated precipitation, we conducted the simulations under an historical (1950–1994) precipitation regime.The five management strategies included one with no adjustments to stocking rate (CONTROL, most common current practice), one with stocking rate adjustment rules based on changes in animal body condition (BCS), and three with different stocking rate adjustment rules based on various comparisons of recent-year precipitation with long-term mean precipitation during the growing season (March–November) (REPLA, PPT 1Y, PPT 2Y). Each strategy was evaluated at each of three initial base-level stock cow stocking rates (125, 250 and 500 AUY · 5000 ha⁻¹). Stocking rate adjustments consisted of partial or total de-stocking, with the re-establishment, or not, of the initial number of stock cows before the beginning of the subsequent breeding season.Results of 45-year simulations under both random and historical precipitation suggest CONTROL and PPT 2Y (based on comparison of current year and previous year precipitation with the long-term mean) strategies, combined with the high base-level stocking rate, are the worst and best, respectively. Under the historical precipitation regime, in the last period of time simulated (1980–1994) these two strategies resulted, respectively, in poor (0.5) versus good range condition (1.0), animal body condition scores of 2.6 versus 5.2, annual cow mortalities of 76 versus 5%, and calf production rates of 0.9 versus 10.6 kg ha⁻¹ year⁻¹ at weaning. The PPT 1Y strategy (based on comparison of current year precipitation with the long-term mean) produced results fairly similar to PPT 2Y, with BCS and REPLA strategies producing results intermediate between CONTROL and PPT 2Y. Our results suggest it is advantageous to adjust stocking rates based on precipitation during the current growing season since it improves cattle production without damaging range condition. Considering the practical feasibility of the strategies, we recommend the PPT 1Y strategy because it maintains range condition at moderate stocking rates, results in good animal performance and does not require total de-stocking of the ranch.The simple method we developed to stochastically generate monthly precipitation produces a time series of precipitation values that were representative of general historical precipitation patterns and provided realistic levels of uncertainty in simulated forage production to evaluate alternative management strategies.     

离心泵内部动静干涉作用的数值模

采用压力边界条件对一单级单吸蜗壳式离心泵进行了三维非定常数值模拟计算,模拟过程中给定离心泵入口总压和出口静压,结合滑移网格技术,成功地捕捉了叶轮-蜗壳的动静干涉作用引起的非定常流动特性.计算结果表明,离心泵内流场周期性脉动明显,蜗壳内静压及叶片载荷分别以叶片旋转频率、叶轮旋转频率发生周期性变化.蜗壳几何形状的不对称性影响了动静干涉作用在离心泵内部的传播,引起了离心泵内流动沿周向分布不均匀现象.