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随着贝类底播增养殖产业的迅猛发展,为保证底播贝苗的成活率,养殖企业对天然苗种更加重视。天然苗种采用中间育成方法,需要对苗种进行筛选作业,但目前筛选作业仍以人工作业为主,存在作业效率低、劳动强度大等问题。作者通过对大连地区虾夷扇贝(Patinopecten yessoensis)天然苗种筛选作业调研的基础上,设计了满足生产实际需求的扇贝苗种筛选装置,可实现3种规格贝苗的筛选作业。试验分2阶段进行,第1阶段对影响筛选准确性的因素进行正交分析于验证,确定了最佳工艺参数;第2阶段在大连旅顺进行的生产性对比试验得出,机械筛选的平均准确率为91.33%,误差率低于10%,且5组筛选结果无显著性差异(P0.05);同时机械筛选的平均作业效率为80g/(人/min),约为人工筛选作业效率的8倍。由此说明扇贝苗种筛选装置具有较高的准确性、稳定性和高效性,具有推广应用价值。 相似文献
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Patinopecten yessoensis is a commercial valuable species. This study deals with the effect of nutrient effects of the broodstock(mainly ovaries) on the larvae. Concentrations of total carbohydrate, total protein and total lipid in the gonads of P. yessoensis from three Hatcheries(Hatchery 1, Hatchery 2, and Hatchery 3) were determined before and after spawning. The relationship between the nutrient concentration in ovaries before spawning(BC) and that of larvae(LC) was assessed as well as the change in nutrient levels in ovaries after spawning(DC). Results indicate that the BC of total carbohydrate(7.66%) and total lipid(14.48%) in ovaries were significantly higher than in testes(5.20%, 5.20% respectively), whereas the BC of total protein in the ovaries was lower(61.76%) than in the testes(81.67%). The different gonadal composition suggests the different nutrient demands between male and female broodstocks in breeding season. P atinopecten yessoensis gonads contained a higher proportion of lipids, in comparison to other bivalves, which might be a response to the low ambient water temperatures. Further analysis of fatty acids showed that the concentrations of n-3PUFA, EPA and DHA in larvae(LC) were positively correlated with BC and DC, indicating the significant nutrient influence of broodstocks on the larvae. As these fatty acids are important in metabolism, and have been demonstrated to be influential to the viability of the larvae, larval growth and the settlement, spat growth, and juvenile survival in many bivalves, they could possibly be used as indexes to evaluate, and predict condition of broodstocks and larvae. 相似文献
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新疆博斯腾湖水生态演变分析 总被引：1，自引：0，他引：1
博斯腾湖是我国最大的内陆淡水湖,湖水水面积为1 160 km^2,湖水容积84.1×108m^3,水深在8～15 m之间,平均水深8.1m。具有蓄洪灌溉,提供丰富的水生动植物资源、改善焉耆盆地及塔里木河下游生态系统与环境、发展旅游业、促进区域经济可持续发展等多种功能。近50年来博斯腾湖水环境的变化,引起众多专家学者的关注。经过实地考察、调查、取样分析和系统研究认为要使博斯腾湖的含盐量降低到和保持在1.0 g/L以下,必须采取一系列措施。 相似文献
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用地面观测日平均气压差与气温日较差统计分析,寻找5月份≥5级大风的气压与温度变化的关系,用统计数据制作点聚图,发现了大风在点聚图上的集中落区;制作了曲线图;用历年4月下旬平均最高、平均最低气温,寻找冷暖气团春季进退早晚与5月大风多少的关系。经统计发现,在5月份出现≥5级大风起报日的温度日较差临界值,即在日平均气压差(Δp24)与气温日较差(Tm-Td)的曲线图模型上,是该报大风,日较差必须在13.5℃或以上,锁定了模式出现后是否有大风的第一关,起报日当天升温值必须≥5℃,这是该模型是有大风的第二关。大风模型和数据相互关联制动,有效的提高了预报大风的可信度。 相似文献
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小兴安岭伊春林区森林火灾特征及变化规律分析 总被引：3，自引：0，他引：3
基于伊春林区1953～2004年的林火资料,分析研究林区火灾发生特征,结果表明:19532004年,伊春林火发生总次数年际变化呈下降趋势,到90年代下降至最低,近年有所回升.其中重大火灾和特大火灾的次数年际变化不大.伊春森林火灾主要是由人为因素引起的.总火灾面积年际变化,以1978年为界存在明显的两个阶段,1978年以前为森林火灾受害严重阶段,1979以后为森林火灾受害轻微阶段.伊春森林火灾主要发生在4～6月和9～10月份.无论是火灾发生的次数,还是火灾发生面积,峰值均主要发生在12:00～14:00左右. 相似文献
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黄河内蒙古河段冲淤演变及其影响因素(英文) 总被引：5，自引：2，他引：3
Rivers with fluvial equilibrium are characterized by bed deformation adjustment. The erosion-deposition area in cross-section reflects this characteristic, which is a base of researching the river scour and deposition evolution by time series analysis. With an erosion-deposition area indicator method proposed in this paper, the time series of erosion-deposition area quantity at Bygl and Shhk stations were obtained with the series duration of 31 years from 1976 to 2006. After analysis of its trend and mutation, three different ten- dencies about the evolution were observed in general from the quasi-equilibrium phase through a rapid shrinkage to the final new quasi-equilibrium. It is also found that the trend of erosion-deposition area series will change once a big flood occurred in some of the tributaries, and its ever greater influence is due to the decrease of deluge with the completion of upstream reservoirs. Almost all the turning points were coincident with the time when hyper-concentrated sediment flood occurred in some tributaries. With the time series of clear mutations since the late 1990s, the Inner Mongolian Reach has been in a new equilibrium phase. This can be concluded in two aspects. 1. The absence of big floods and sediment transportation from tributaries result in the river shrinkage, and to regain the channel flow-carrying capacity in Inner Mongolian Reach a large flood is needed both of high peak discharge and of lengthy interval to destroy the new equilibrium. 2. The proposed method of erosion-deposition area indicator is of great help to channel scoureposition evolution analysis because it can demonstrate real time deformation of cross section in quantity. 相似文献
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本文利用伊春地区5个气象观测站1970-2009年日平均气温稳定通过10℃的积温资料进行分析。结果显示伊春地区积温呈增加趋势,平均每10 a积温增加了71.0℃;40 a积温存在明显的年代际变化,每10 a的变化规律为增加-下降-增加;积温稳定通过10℃初日提前了2 d,终日推后了3.3 d,初终间日数增加,积温也就随之增加。 相似文献
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本文利用统计分析方法对逊克县1961～2005年共45 a的气候资料进行了分析,探讨出了逊克近45 a的温度要素的变化规律,得到以下主要的结果:逊克县自1961～2005年,45 a平均气温以0.387℃/10 a的趋势变暖,年平均最高温度和年平均最低气温也呈增暖的趋势。一年四季中,夏季平均气温和平均最高气温、平均最低气温升高趋势幅度略低于其他季节,春季、秋季和冬季的年平均气温、平均最高气温和平均最低气温都呈上升趋势,其中冬季的变暖最为突出,平均温度以0.608℃/10 a的变化率升高。 相似文献