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大弹涂鱼仔、稚、幼鱼消化系统的发育及其食性的研究 总被引：12，自引：0，他引：12
本文观察描述了人工培育的大弹涂鱼仔、稚鱼和早期幼鱼消化器官的发育过程,并对各发育阶段的食性进行较深入的分析。开口摄食期主要摄食微型颗粒有机碎屑;全长3.55mm以上,同时还援食桡足类无节幼体、桡足幼体及其成体;全长7.50mm以上,桡足类成体已取代有机碎屑而成为主要饵料。进入幼鱼期后,转变为摄食底栖硅藻为主,兼食桡足类和海泥中的有机碎屑。 相似文献
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大亚湾中型浮游动物群落结构和植食性 总被引：2，自引：0，他引：2
本文以中型浮游动物成体为研究对象,通过在大亚湾实验站附近一个采样点连续两年的野外调查和现场摄食实验,分析大亚湾近岸富营养化海域中型浮游动物的群落特征,及其对浮游植物的选择摄食特性。结果表明:2015—2017年实验站附近中型浮游动物的总丰度在冬季达到最高,其次为春、秋和夏季;其优势种大多是滤食性桡足类,如锥形宽水蚤(Temora turbinata)、中华哲水蚤(Calanus sinicus)等,中型浮游动物的摄食特性与优势种摄食行为有很大的相关性。中型浮游动物群落更偏好于粒径较大的小型浮游植物(20—200μm),而对微型(2—20μm)或超微型浮游植物(0.7—2μm)的摄食影响较小,甚至会因为选择性摄食对这两种类型的浮游植物的生长有间接促进作用。且中型浮游动物的摄食选择性具有明显的季节性,除每个季节均倾向于摄食甲藻和青绿藻。除此之外,在春季偏好于定鞭藻和隐藻,夏季偏好于定鞭藻和绿藻,秋季偏好于硅藻、隐藻和聚球藻。尽管硅藻的生物量在调查期间平均约占总浮游植物类群的50%,但是中型浮游动物并不主动摄食硅藻,而更偏爱生物量低但营养较高的甲藻。总体上,中型浮游动物虽然对浮游植物有一定的摄食,但其植食性较弱,不能对浮游植物的生物量进行有效控制。 相似文献
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崂山湾潮间带食物网结构的碳稳定同位素初步研究 总被引：14，自引：3，他引：14
通过对1993年8月和1994年2和5月在崂山湾潮间带采集的底栖生物碳稳定同位素组成(δ13C值)的分析,发现该区底栖动物的主要食物来源以δ13C值大致可划分为4类:水体中的颗粒有机质(POM)、底栖硅藻、大型底栖藻类和底泥中的有机物质(SOM).研究结果表明,底栖动物的碳稳定同位素组成与其所摄食的食物的碳稳定同位素组成有密切的关系,因此,底栖动物的碳稳定同位素组成可以用于研究其食物来源.碳稳定同位素数据证实,双壳类等滤食性动物的食物来源主要是POM;甲壳动物的δ13C值的范围较大,证明其食物来源的多样性;底栖硅藻是多数腹足类食物来源的相当重要组成部分.用碳稳定同位素示踪剂对该区底栖-水体耦合作用的初步研究表明,水体中的POM是底栖动物的重要食物来源,但底泥中有机质和底栖硅藻也是许多底栖动物食物来源的相当重要的组成部分. 相似文献
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渤海中华哲水蚤摄食的初步研究 总被引：17，自引：0，他引：17
于１９９２年８月－１９９３年６月期间，在渤海进行渔业资源增殖生态基础调查， 型浮游生物网采取浮游动物样品，从中取出４００个消化道内含有食物的中华水蚤标本。分析结果表明：中华哲水蚤营浮游植物食性，主要摄食硅藻类、辐射圆筛藻、偏心圆筛藻，未查明的圆筛藻和星脐圆筛藻是它的主要摄食对象。合计占８９．２％；此外，也摄食很少量的甲藻类，金藻类和纤毛虫类，它在渤海所摄食的食物类群，季节变化不大，食物类九更替率各 相似文献
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尖刀蛏食性和食料的研究 总被引：3，自引：2，他引：3
尖刀蛏是竹蛏科刀蛏属的软体动物,广泛分布于印度－西太平洋热带、亚热带沿岸海域。是典型的滤食性动物,但对食物有一定的选择性,食料以底栖性和底层性硅藻为主,随着海区水温的升高和蛏体的长大,摄食强度也加大。 相似文献
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氮磷硅对咖啡双眉藻和缢缩菱形藻繁殖速度和油脂积累的影响 总被引：1，自引：0，他引：1
采用光密度法和尼罗红染色法,探索了氮、磷、硅对从温州海区分离出的底栖硅藻咖啡双眉藻(Amphora coffeaeformis)和缢缩菱形藻(Nitzschia constricta)的繁殖速度和油脂积累的影响。结果显示,2种底栖藻在NO3-N质量浓度为1.746 mg/L时,细胞均不繁殖,且在实验第7天开始死亡,当NO3-N质量浓度再升高后,细胞繁殖速度开始加快,质量浓度达8.820 mg/L后,藻细胞的繁殖速度不再明显加快;2种藻类的繁殖速度均随H2PO4-P质量浓度升高而加快,但当质量浓度达到0.884 mg/L后,藻细胞的繁殖速度不再明显加快;2种底栖藻类均随Si O3-Si质量浓度增加而加快,但质量浓度对2种底栖硅藻细胞繁殖速度影响并不显著。3种元素对2种底栖硅藻繁殖速度的影响力:NPSi。实验期间,2种底栖硅藻的油脂含量均呈先降后升的变化规律,油脂的积累主要集中在实验后期,氮磷硅限制均能促进2种底栖硅藻细胞油脂的积累,对2种硅藻细胞油脂积累的影响程度,氮限制比磷和硅限制都要大。 相似文献
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象山港潮间带底栖硅藻的分布及其与环境关系探讨 总被引：2，自引：0，他引：2
于2005年5月和11月对浙江省象山港潮间带底栖硅藻进行采样调查,分析了底栖硅藻的种类组成、丰度、优势种、多样性及群落结构的季节变化和平面分布特征.并讨论了底栖硅藻与水温、营养盐、潮汐等环境因子之间的关系.共鉴定硅藻33属124种.硅藻数量分布随季节变化明显,春季细胞丰度高于秋季.主要优势种为柱状小环藻(Cyclotella stylorum),春、秋季平均占总细胞数的25.8%.种类的季节变化反应硅藻对水温的适应性,潮汐、盐度、pH值对底栖硅藻组成影响并不明显.秋季营养元素含量升高,多样性指数降低. 相似文献
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Tautog, Tautoga onitis, is an abundant species of fish in estuaries of the northeastern United States. Planktonic tautog larvae are abundant in summer in these estuaries, but there is little information on rates of growth of tautog larvae feeding on natural assemblages of food in the plankton. We examined abundance and growth of larval tautog and environmental factors during weekly sampling at three sites along a nearshore‐to‐offshore transect in Buzzards Bay, Massachusetts, USA during summer 1994. This is the first study of a robust sample size (336 larvae) to estimate growth rates of field‐caught planktonic tautog larvae feeding on natural diets, using the otolith daily‐growth‐increment method. The study was over the entire summer period when tautog larvae were in the plankton. The sampling sites contrasted in several environmental variables including temperature, dissolved oxygen (DO), and chlorophyll a concentration. There was a temporal progression in the abundance of tautog larvae over the summer, in relation to location and temperature. Tautog larvae were first present nearshore, with a pronounced peak in abundance occurring at the nearshore sites during the last 2 weeks in June. Larvae were absent at this time further offshore. From late June through August, larval abundance progressively decreased nearshore, but increased offshore although never approaching the abundance levels observed at the nearshore sites. The distribution and abundance of tautog larvae appeared to be related to a nearshore‐to‐offshore seasonal warming trend and a nearshore decrease in DO. Otoliths from 336 larvae ranging from 2.3 to 7.7 mm standard length had otolith increment counts ranging from 0 to 19 increments. Growth of larval tautog was estimated at 0.23 mm·day?1, and length of larvae prior to first increment formation was estimated at 2.8 mm indicating that first increment formation occurs 3–4 days after hatching at 2.2 mm. Despite spatial and temporal differences in environmental factors, there were no significant differences in growth rates at any of three given sites over time, or between sites. Because larval presence only occurred at a narrow range of temperature (17–23.5 °C) and DO (6.5–9.3 mg·l?1), in situ differences in growth did not appear to be because of differences in larval distribution and abundance patterns relative to these parameters. 相似文献
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Soil-sized particulates have been collected on board ship by a mesh technique from the lower troposphere of the North, Equatorial and South Atlantic Ocean, northern and southern Indian Ocean, South and East China Sea and various coastal localities.Spectrographic analysis reveals that, on average, the particulates have concentrations of Mn, Ni, Co, Ga, Cr, V, Ba, and Sr which are of the same order of magnitude as those in average crustal material. In contrast, the average concentrations of Pb, Sn, and Zn are one order of magnitude higher than those in average crustal material.Within this “world-wide” average there are significant geographical variations in the distributions of Pb, Sn, and Zn which may be related to anthropogenic sources.On the basis of trace-element distributions lower tropospheric soil-sized marine particulates have been divided into four genetic components; local, zonal, inter-zonal, and global. The proportions of these components vary geographically, and each component may have both a natural and an anthropogenic fraction. 相似文献
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Maryd De Wemton John S. Clayton Rohan D. S. Wells Chris C. Tanner Suzanne T. Miller 《新西兰海洋与淡水研究杂志》2013,47(2):145-151
The submerged vegetation of Lakes Sumner, Marion, Katrine, Taylor, and Sheppard was surveyed in May 1987. These high‐altitude lakes lie at c. 600 m a.s.l., within the largely unmodified upper Hurunui catchment. Submerged vegetation was diverse and included numerous short shallow‐water species, dense swards of Isoetes alpinus, low covers of taller native vascular plants, and charophyte meadows beyond the depth limit of vascular plants to a maximum of 15 m. A sparse deepwater bryophyte community was observed from 11 to 32 m depth in Lake Sumner. Displacement of native vegetation by dense growths of the adventive oxygen weed Elodea canadensis over mid‐depths of 3–6 m was noted in all lakes, except Lake Marion. 相似文献
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Klaus Kremling 《Marine Chemistry》1983,13(2):87-108
In June 1981, dissolved Zn, Cd, Cu, Ni, Co, Fe, and Mn were determined from two detailed profiles in anoxic Baltic waters (with extra data for Fe and Mn from August 1979). Dramatic changes across the O2H2S interface occur in the abundances of Cu, Co, Fe, and Mn (by factors of ?100). The concentrations of Zn, Cd, and Ni at the redox front decrease by factors between 3 to 5.Equilibrium calculations are presented for varying concentrations of hydrogen sulfide and compared with the field data. The study strongly supports the assumption that the solubility of Zn, Cd, Cu, and Ni is greatly enhanced and controlled by the formation of bisulfide and(or) polysulfide complexes. Differences between predicted and measured concentrations of these elements are mainly evident at lower ΣH2S concentrations.Cobalt proved to be very mobile in anoxic regions, and the results indicate that the concentrations are limited by CoS precipitation. The iron (Fe2+) and manganese (Mn2+) distribution in sulfide-containing waters is controlled by total flux from sediment-water interfaces rather than by equilibrium concentrations of their solid phases (FeS and MnCO3). The concentrations of these metals are therefore expected to increase with prolonged stagnation periods in the basin. 相似文献
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While clastic mudstones and shale were traditionally interpreted to have been deposited in quiet water settings, recent flume experiments and studies have shown that mud can be transported in and deposited by traction currents as migrating ripples of mud aggregates. Despite these recent advances, mud aggregates have rarely been adequately described in the rock record.These mud aggregates and the sedimentary structures they form in mudstone successions are difficult to observe in the rock record due to compaction, which often obliterates the aggregates and flattens bedforms. This paper documents unambiguously identifiable sand sized mudstone aggregates in thin sections and SEM, transported in traction, and deposited in a series of prograding clinothems. These aggregates were sufficiently indurated to locally preserve shelter porosity, significantly improving the hydrocarbon reservoir properties.Grain size analysis of the aggregates was performed on thin sections, as well as disaggregated samples measured by a laser diffraction grain size analyzer for comparison. These analyses showed that sand sized aggregates often comprise more than half of the sediment volume. While the clay-rich composition of the Carlile Formation would suggest that it is a mudstone, statistical analysis of these grain size measurements show that it could alternatively be described as a silty sandstone. These findings potentially change how we think about mudstone classification, fine-grained sedimentation, and mudstone dominated petroleum reservoirs. 相似文献
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The radiometers on board the satellites ERS-1, TOPEX/Poseidon, ERS-2, GFO, Jason-1, and Envisat measure brightness temperatures at two or three different frequencies to determine the total columnal water vapor content and wet tropospheric path delay, a major correction to the altimeter range measurements. In order to asses the long-term stability of the path delay, the radiometers are calibrated against vicarious cold and hot references, against each other, and against several atmospheric models. Four of these radiometers exhibit significant drifts in at least one of the channels, resulting in yet unmodeled errors in path delay of up to 1 mm/year, thus limiting the accuracy at which global sea level rise can be inferred from the altimeter range measurements. 相似文献
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Izvestiya, Atmospheric and Oceanic Physics - Data on the relative contribution of the Ox, HOx, NOx, ClOx, BrOx, and IOx catalytic cycles to atmospheric ozone destruction are given for June and... 相似文献
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Cross-Calibration and Long-Term Monitoring of the Microwave Radiometers of ERS,TOPEX, GFO,Jason, and Envisat 总被引：1，自引：1，他引：0
The radiometers on board the satellites ERS-1, TOPEX/Poseidon, ERS-2, GFO, Jason-1, and Envisat measure brightness temperatures at two or three different frequencies to determine the total columnal water vapor content and wet tropospheric path delay, a major correction to the altimeter range measurements. In order to asses the long-term stability of the path delay, the radiometers are calibrated against vicarious cold and hot references, against each other, and against several atmospheric models. Four of these radiometers exhibit significant drifts in at least one of the channels, resulting in yet unmodeled errors in path delay of up to 1 mm/year, thus limiting the accuracy at which global sea level rise can be inferred from the altimeter range measurements. 相似文献