牡蛎对浮游植物群落下行控制作用的围隔实验研究

牡蛎的滤食作用不但能控制浮游植物丰度,还能通过摄食选择性影响群落结构。通过在较高营养水体的围隔实验表明,牡蛎养殖在持续磷限制条件下,促使浮游植物群落由甲藻向小型硅藻优势转变。实验结束时对照组中浮游植物群落由扁压原甲藻主导,占总丰度的77%;而牡蛎养殖组新月柱鞘藻丰度占比达到93%。牡蛎养殖组中,甲藻去除速率随养殖密度增长,但是硅藻最终丰度在高密度牡蛎组最高。研究结果说明大量的贝类养殖能够提升小型链状硅藻的优势度,增加此类赤潮发生风险。     

一种池塘陆基实验围隔

该陆基围隔适用于池塘养殖学与生态学研究。围隔面积为２５ｍ２（５ｍ×５ｍ）,水面以上超高０．３～０．５ｍ,水深１．５～１．８ｍ,容积３７．５～４５ｍ３。以木桩及青竹构成支架;以涂塑高密度聚乙烯编织布为隔水材料（围隔幔）,将其包围并固定在支架上。因围隔内受风力影响较小,为了模拟池塘水的混合状况,围隔中设１台９０Ｗ的微型电动搅水机。４年（１９９４～１９９７）的使用结果表明围隔效果良好,其中的生态系发育与运行正常,放养的养殖生物生长良好。专门的观测证明空白围隔与设置围隔的空白池塘理化条件的数值和变动都基本一致。研究结果证明,此种围隔完全可以替代池塘用于养殖学与生态学方面的实验研究,不失为一种有效、经济而方便的科学研究设施。     

氟苯尼考对太平洋牡蛎(Crassostrea gigas)早期发育的影响

氟苯尼考作为氯霉素的替代物,理化性质稳定,在水产养殖业中被广泛使用,致使其在多种水体环境中大量残留。本研究分析了氟苯尼考(0.1、1.0和10 mg/L)对牡蛎幼虫的生长发育、运动能力、免疫抗性的影响。结果表明,氟苯尼考暴露24 h后,随着暴露浓度的增加,牡蛎幼虫的存活量呈升高趋势,而幼虫壳高和壳宽显著降低;氟苯尼考暴露不会引起牡蛎幼虫移动速度的变化,1 mg/L氟苯尼考暴露后,牡蛎幼虫移动距离呈显著性增加(P<0.05)。氟苯尼考暴露浓度、牡蛎幼虫存活量及水体细菌总数之间呈显著性相关,但水体细菌总数的变化并不是造成牡蛎幼虫发育、生长状态不同的主要原因。牡蛎幼虫在不同浓度氟苯尼考的暴露下,ILPR、Cg-Tyr和Ferritin等生长发育相关基因的表达受到影响,进而影响其生长发育、运动能力。另一方面,高浓度氟苯尼考的暴露,引起牡蛎幼虫HSP70和Cg-Tal基因相对表达量上调,积极地参与抵抗氟苯尼考暴露引起的应激反应。养殖水环境中抗生素残留可能会影响水生动物早期发育阶段的生长发育及免疫抗性,需提高对养殖水体中抗生素残留危害的认识及监测,进一步加强养殖水体水质的净化。     

对虾综合养殖生态系有机碳的平衡

采用围隔实验生态学方法研究了对虾综合养殖生态系有机碳的平衡,结果表明:(1)研究期间各实验围隔有机碳的总收入量为4847.46～6154.67 g,平均为(5646.94±551.09)g.有机碳总收入量与浮游植物生产量、附生藻类生产量及颗粒饲料(含饵料鱼)等各组分碳收入量的比例平均为1:0.73:0.11:0.16.(2)研究期问各实验围隔有机碳的总支出量为3310.28～3974.79g,平均为(3644.21±281.44)g.有机碳总支出量与浮游生物群落呼吸量、附生生物群落呼吸量、底栖群落呼吸量、养殖生物生产量、养殖生物呼吸量等各组分碳支出量的比例平均为1:0.53:0.19:0.15:0.04:0.09.(3)各实验围隔有机碳积累量为1383.45～2707.31 g,平均为(2002.73±546.76)g,占收入量的(35±7)%(26%～44%).不同养殖模式实验围隔依积累量大小顺序为:Y5(对虾-扇贝)、Y7(对虾-罗非鱼)、Y4(单养对虾)、T5(对虾-罗非鱼-缢蛏)、Y6(对虾-缢蛏).(4)围隔收入的有机碳对对虾的转化率为(1.77±0.62)%(0.76%～2.28%),转化率大小顺序为Y6,T5,Y4,Y5,Y7,收入的有机碳对全部养殖动物的转化率为(2.18±0.79)%(1.07%～3.12%),转化率大小顺序为T5,Y6,Y5,Y4,Y7.     

不同养殖方式对海水实验围隔底泥中氮、磷和有机碳含量的影响

①对养殖池塘底质的研究目前尚较少［２］。由于放养生物对投入的饵料和肥料的利用率很低,经过多年养殖的池塘底部往往会形成很厚的淤泥,底泥中有机质大量积累后容易形成厌氧微环境［３］,对底栖生活的养殖种类造成危害,因此,减轻养虾池底质中有机质的积累是改善对虾养殖环境的重要内容。作者１９９５,１９９６年进行了两次围隔养殖实验。本文初步讨论了不同养殖方式对海水实验围隔底泥中有机碳和氮磷含量的影响,以期为今后对虾池养殖生态系统结构优化提供基础资料。１材料和方法实验的时间、地点、围隔构造以及放养和管理的有关细节…     

两种围栏养殖模式防白斑综合征病毒(WSSV)效果的比较

2003年在乳山养殖场采用两种围栏养殖模式养殖了凡纳滨对虾,并对其防白斑综合征病毒(WSSV)效果进行了比较。结果表明,凡纳滨对虾在养殖过程中WSSV阳性率有下降趋势,浮游动物WSSV阳性率较低,布围隔的防病毒效果好于网围隔。     

近江牡蛎的摄食习性

牡蛎(Ostrea)是重要的经济贝类之一,我国广东、福建沿海个别地区养殖的近江牡蛎(O. rivularis Gould)为其中经济价值巨大的一种。 世界学者们在牡蛎的研究方面已经做了许多工作,对壮蛎的养殖生产曾起了很大的推动作用;但目前在基础理论和实际应用方面,都还存在着很多需要研究和争论未决的问题,牡蛎的摄食习性就是其中之一。     

中国对虾、非鲫和海湾扇贝对海水实验围隔中悬浮物沉积的影响

养殖池塘水中悬浮物通常由浮游植物、腐屑和粘土颗粒组成。其中浮游植物和腐屑是滤食性鱼类和贝类的天然饵料,而悬浮粘土则往往对养殖生物不利。对养殖池塘悬浮物的组成和数量及其动态变化的研究目前尚不多见,这不利于深入了解池塘内物质循环的过程。本文初步报道了中国对虾、非鲫和海湾扇贝对海水养殖实验围隔内悬浮物沉积的影响,旨在为今后海水养殖池塘生态系统结构的优化提供基础资料。1　材料和方法实验分别于1995年和1996年的6～9月间进行,实验地点、围隔的构造以及两年实验中围隔的放养和养殖管理细节详见另文。1995年在p2,pf1,pf2,pf…     

单体牡蛎培育技术

牡蛎在世界上是第一大养殖贝类,在我国为4大养殖贝类之一。它肉味鲜美,营养丰富,被称为海洋中的“牛奶”,深受广大国内外消费者欢迎。 牡蛎有100多种,而我国比较常见并用于养殖的种类主要有5种:大连湾牡蛎、褶牡蛎、长牡蛎、近江牡蛎、密鳞牡蛎。牡蛎养殖在世界     

长牡蛎(Crassostrea gigas)黑色壳表面微生物多样性的研究

为探究自然海区与室内养殖环境对软体动物壳色及壳表面细菌群落多样性的影响，以黑色壳长牡蛎（Crassostrea gigas）为研究对象，在自然海区与室内环境分别暂养30 d后，对长牡蛎的壳色及壳表面细菌群落的多样性和差异细菌功能进行分析。结果表明，室内养殖的黑壳长牡蛎出现较为明显的壳褪色现象，其黑色素含量显著下降，远低于自然海区养殖的黑壳长牡蛎。16S rRNA基因测序结果显示，变形杆菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）、蓝细菌（Cyanobacteria）为长牡蛎壳表面的主要优势菌，其中变形杆菌的丰度超过50%。在门水平上，放线菌（Actinobacteria）、俭菌超门（Parcubateria）和Bacterial rice cluster 1（BRC1）在室内、外养殖长牡蛎之间存在较为显著的差异（P<0.05），而具有降解作用的放线菌和俭菌超门细菌在室内养殖的黑壳长牡蛎壳表面丰度较高。在属水平上，两组之间存在显著差异的细菌共计67种。该研究揭示了不同生境条件下，黑壳长牡蛎壳表面的微生物群落物种组成及差异，为解析长牡蛎壳色的形成机制提供了新的分析视角。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

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.     

A Review of Some Environmental Issues Affecting Marine Mining

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.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

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.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

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.     

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.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

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。     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

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.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

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.     

《Acta Oceanologica Sinica》Vol. 33(2014) contents

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