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1.
塑料大棚商品苗的出棚时间为４月２８日，较以前的露天虾池保苗提早１．５月；出棚商品苗壳高为４．１±２．０ｍｍ，是同期海区苗壳高的２倍，保苗率为２９．７％，与同期海区保苗相比提高１倍以上。 相似文献
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塑料大棚池蓄养海湾扇贝亲贝试验 总被引：1，自引：0，他引：1
海湾扇贝（Ａｒｇｏｐｅｃｔｅｎ ｉｒｒａｄｉａｎｓ）室内人工育苗工艺中亲贝控温蓄养成本高、难度大，因此有必要研究一种既简易又能获得优良亲贝的蓄养方法。作者从利用塑料大棚的温室效应进行作物育种及栽培中受到启示，在日照市石臼镇一村育苗厂进行了用塑料大棚的温室效应来提高水温蓄养海湾扇贝亲贝的试验。１材料和方法１．１塑料大棚池为水泥石砌结构，东西向，呈长方形，长４０ｍ，宽１６．７ｍ，池深２ｍ，水深１．７ｍ，面积６６７ｍ２，池子上方为拱型钢梁结构，钢梁顶部覆盖厚度０．５ｍｍ的透明塑料薄膜。１．２．１月２７… 相似文献
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“莱州市金城海湾扇贝千亩万斤丰产方技术开发”通过了专家验收评议。从１０８０亩丰产方中，在西、中、东３个部位任选３点，每点随机抽取１０笼扇贝，称出全笼净重，按４００笼／亩折算出每亩产量。从样品中任取５０个扇贝测壳高，算出平均值。称出５ｋｇ扇贝，剖出鲜贝柱称重。平均亩产５５６０ｋｇ，出鲜柱率１６．７％，两项指标均创全国最高纪录。１材料与方法１．ｌ养殖海区自然条件试验海区位于金城镇近海，离岸边距离１５００ｍ以上，水深９．５～１２ｍ，底质为泥沙，上半年透明度４～７ｍ，下半年２～４ｍ。本海区为西南、东北往… 相似文献
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以湛叉鞭金藻为主，盐藻为辅投喂虾夷扇贝的结果，使虾夷扇贝幼早浮期缩短了５－６ｄ，日生长平均为１０．６μｍ，最快时达到１４．６μｍ，附着率达５１．２％，育出壳高５９０μｍ稚贝，平均单位水位体育苗４４１万个／ｍ＾３，成倍提高了虾夷扇贝单位水体出苗量。 相似文献
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１基本情况与结果１９９２年５月，我们利用莱州市渔业公司养虾场一个４７．２亩的虾池进行海湾扇贝保苗。该池东西长、南北短，海湾扇贝苗安排在有排水闸的东半部，占虾池面积２３亩。５月２９日，贝苗壳高达到２～４ｍｍ，全部出地移到海上。保苗过程中，部分小苗钻出苗袋，脱落到虾池中．６月１５日，将该池水放干重新换上新水，每亩放养体长３ｃｍ的虾苗１９０００尾，进行虾贝混养。日常管理均按对虾养殖的方法进行，虾贝生长皆很好。由于海湾扇贝大量滤食池水中的单细胞藻类和有机碎属等，虾池东半部逐渐变清，到７月中旬后，虾池东半… 相似文献
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魁蚶育苗在我国是近几年刚发展起来的［１，２］，育苗水体较小，再加上幼虫培育时间长，幼虫成活率、变态率不及扇贝高，造成了出苗量不高。为此作者探索了一套魁蚶大水体升温育苗稳产技术措施，１９９３年在３１２ｍ３水体中育出０．５ｃｍ苗种９．３６×１０７粒，单位水体出苗量达３０００００个／ｍ３以上。１材料与方法１．１材料１．１．１亲贝分别于５月１２，１５，１６，１７日人工潜水捕自荣成近海，壳长为５～１０ｃｍ的２～４龄贝，共５４００个。１．１．２饵料主要是等鞭金藻３０１１，塔胞藻，小球藻等高温种类。亲贝蓄养以… 相似文献
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海湾扇贝大水体高产育苗技术的研究 总被引：1，自引：0，他引：1
本文主要用延长亲贝低温培育时间和强化营养，抛劣优质亲见等措施，保证亲贝和积温达４００℃以上产卵。在此技术上严格控制亲贝产卵时间和精子浓度，逐步提高幼虫培育水温，回在换水和投饵，勤倒池等措施，于２９９ｍ＾３水体中，培育出２．６５亿粒商品苗（０。５ｃｍ大小），取得可喜的经济效益。 相似文献
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Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance. 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
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Derek V. Ellis 《Marine Georesources & Geotechnology》2001,19(1):51-63
This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested. 相似文献
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G. Parthiban 《Marine Georesources & Geotechnology》2000,18(3):223-235
Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement. 相似文献
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海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。 相似文献
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Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification
An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
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The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments. 相似文献
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The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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