Macroalgal assemblages of disturbed coastal detritic bottoms subject to invasive species     

Judith C. Klein  Marc Verlaque 《Estuarine, Coastal and Shelf Science》2009

Characteristic flora and fauna that are highly sensitive to disturbances colonize coastal detritic bottoms in the Mediterranean Sea. In the present study, a comparison of the assemblage composition and colonization by invasive macroalgae was made between two coastal detritic macrophyte assemblages, one dominated by rhodoliths (free-living non-geniculate Corallinales) and the other dominated by fleshy algae, in an area that has been exposed to important levels of anthropogenic disturbance, mainly pollution (including changed sedimentation regimes) in the recent past (bay of Marseilles, France). In comparison with less strongly impacted Mediterranean regions, the macrophyte assemblages in the bay of Marseilles were characteristic in terms of species identity and richness of coastal detritic macrophyte assemblages. However, extremely low species abundance (cover) was observed. As far as invasive species were concerned, Caulerpa racemosa var. cylindracea was only abundant in the rhodolith assemblage whereas the two invasive Rhodophyta Asparagopsis armata and Womersleyella setacea were mainly found in the fleshy algae assemblage. The seasonality observed in the Rhodolith assemblage seemed to be related to the development of C. racemosa var. cylindracea and did not follow the typical pattern of other Mediterranean assemblages. This study represents the first study of coastal detritic assemblages invaded by C. racemosa var. cylindracea.  相似文献   

智利外海茎柔鱼生物学特性的初步研究   总被引：2，自引：0，他引：2  

刘必林  陈新军  钱卫国 《广东海洋大学学报》2009,29(1)

根据2007年1月和5～6月我国鱿钓船在智利外海的调查数据,对茎柔鱼生物学特性进行初步分析。结果表明:该地区茎柔鱼胴长范围287～702 mm,优势胴长为380～430 mm,占64.2%;体重范围0.63～11.3 kg,优势体重为0.5～2.0 kg,占75.6%;调查海区渔获个体自西向东、自南往北呈现增大趋势;依据胴长组成推断调查海域可能存在3个群体。生长指数大于3,与秘鲁外海茎柔鱼相近;雌雄性比约为3:1,性腺成熟度以Ⅰ期为主,占92%;摄食等级0～2级为主,约占73%;当地时间00:00后摄食量增大,胃含物以鱿鱼和中上层小型鱼类为主。  相似文献   

Temporal and spatial distribution of dissolved copper, lead, zinc and cadmium in the Changjiang Estuary and its adjacent waters     

WANG Changyou  WANG Xiulin  WANG Baodong  ZHANG Chuansong  SHI Xiaoyong  ZHU Chenjian 《海洋学报(英文版)》2008,27(4):73-82

Heavy metal concentrations were measured in the Changjiang Estuary and its adjacent waters. Results from a systematic survey in April 2002 to March 2003 indicate that the ranges of the concentrations of dissolved copper, lead, zinc and cadmium in the study waters are 1.01 - 6.86, 0. 10 - 0.39,3.17 - 9.12 and 0.011 - 0. 049 μg/dm^3 , respectively. Similar to zinc, the behavior of dissolved copper was essentially conservative, but high scatter has been observed for high salinity samples, which can be attributed to the decomposition or mineralization of organic matter by bacteria. Dissolved lead may have active behavior with an addition at high salinity. Overall concentrations of dissolved cadmium increase with salinity. The mean values of these dissolved metals calculated for the surface waters were higher than those for the middle and bottom ones. External inputs of dissolved heavy metals to the surface waters were the likely explanation for these higher values. The maximum seasonal average values of dissolved copper and zinc were found in summer, reflecting higher amounts of riverine input in this season. In contrast, the maximum seasonal average values of dissolved lead and copper were found in winter and the lowest ones in summer, respectively, which might be asso- ciated with a combination of low concentration with heterogeneous scavenging. Concentrations of these dissolved metals found for the Changjiang Estuary fall in the range observed for the other estuaries but are noticeably higher than those from uncontaminated rivers, except for cadmium. Compared with observations for the Changjiang Estuary in the last two decades, it is clear that the Changjiang estuarine waters has been contaminated with copper, lead, zinc and cadmium during China＇ s industrialization, but concentrations of them have decreased in the last few years.  相似文献   

生物滤料对翘嘴红鲌生长、水质及细菌变化的影响     

赵永锋  刘波  周群兰  王广宇  何义进  谢骏  戈贤平 《广东海洋大学学报》2009,29(4):36-40

在实验池投放一定数量的生物刷和生物球等生物滤料,研究其对翘嘴红鲌生长、池塘水质及细菌变化等的影响。结果表明:与对照池相比,实验池翘嘴红鲌生长有增加趋势,对池塘水温、pH、DO、TP、H2S等指标无显著影响(P>0.05),但是在30 d时水体COD显著降低(P<0.05);在90 d时NH4-N显著降低(P<0.05);在60 d和90 d时NO2-N显著降低(P<0.05);与对照池相比,在30 d时实验池水样与生物球中异养菌的数量显著增加(P<0.05);在30、60 d时,实验池生物刷中异养菌的数量显著增加(P<0.05);在90 d时实验池水样、生物球、生物刷氨化细菌、反硝化细菌的数量显著增加(P<0.05);实验池水样、生物球分别在30、90 d时弧菌数量显著降低(P<0.05)。表明生物滤料可增加池塘的异养菌、氨化细菌、反硝化细菌数量,降低水体弧菌数量,一定程度上改善养殖水体,促进鱼体生长。  相似文献   

Simulating the interaction of seagrasses with their ambient flow     

Jan O. Backhaus  Jennifer J. Verduin   《Estuarine, Coastal and Shelf Science》2008,80(4):563-572

The interaction of seagrasses with the dynamics of an oscillatory wave induced flow is assessed with a new Lagrangian plant model. The plant model simulates moving plants in canopies and their dissipative effect on the ambient flow. Concomitantly the plant model is interactively coupled to a 3D hydrodynamic numerical model allowing for a bilateral feedback between moving plants and flow. Model results demonstrate that this interaction causes a modification of current profiles within and above a canopy as compared to an undisturbed flow. While the overall effect of submerged plant canopies is a dampening of dynamics, the flow may locally be intensified. The model predicted an intensification of the flow near the top of a canopy in concurrence with field and laboratory observations. Dissipation in the coupled model, due to the applied non-linear friction law, grows exponentially with increasing flow. As a result the permeability of a canopy to the ambient flow decreases with increasing dissipation. Consequently, at high flow velocities, while becoming increasingly impermeable, a canopy acts like an obstacle that deflects the flow above it, which causes the observed intensification. Results for canopies consisting of seagrasses with different leaf structure and plant geometry show remarkable differences in predicted plant motions, current profiles, drag forces, and velocity shear. Predictions for moving plants are compared with those for rigid, less flexible, structures and undisturbed flow.  相似文献   

芽孢对提高好氧颗粒污泥环境耐受力的作用     

王琳  林跃梅 《中国海洋大学学报(自然科学版)》2008,38(6)

为研究好氧颗粒污泥中大量存在的芽孢对其环境耐受力的作用,将好氧颗粒污泥经过低温无营养、高温高压、冷冻和紫外线处理后,监测其活性恢复过程中2,6-吡啶二羧酸根(dpa)的释放、比耗氧速率(SOUR)和以还原2,3,5-氯化三苯基四氮唑(TTC)为标志的脱氢酶的活性变化.实验结果显示,好氧颗粒污泥中大量存在的芽孢在不良环境条件下处于休眠状态,环境条件改善后能迅速转化为繁殖体细胞,进行正常的代谢活动.作为潜在的生命力,好氧颗粒污泥对不良环境的耐受力增强.芽孢是好氧颗粒污泥不容忽视的重要组分.  相似文献   

Erratum: A radio survey of seven southern X-ray luminous clusters of galaxies     

《Monthly notices of the Royal Astronomical Society》2009,394(2):1120-1120

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Analyzing the habitat suitability for migratory birds at the Chongming Dongtan Nature Reserve in Shanghai,China   总被引：1，自引：0，他引：1  

Bo Tian  Yunxuan Zhou  Liquan Zhang  Lin Yuan 《Estuarine, Coastal and Shelf Science》2008

The Dongtan Nature Reserve, one of the largest nature reserves in East Asia, is located in the mouth of the Yangtze Estuary and is an important habitat for migratory birds. The Dongtan wetlands were listed in the Chinese Protected Wetlands in 1992, and were designated as internationally important under the Ramsar Wetlands Convention in 2001 and as a national nature reserve in 2005. By their very nature and location, the estuarine and coastal habitats are dynamic and their biodiversity conservation and management relies on up-to-date spatial information. By establishing qualitative and quantitative relationships between bird populations and key habitat factors such as elevation, land cover type, tidal creek density and macrophytobenthos biomass, we developed an object-oriented image approach, in conjunction with Geographical Information Systems and the data from current field surveys, to analyze and assess the habitat suitability for the main types of birds, namely Anatidae, Charadriidae, Ardeidae and Laridae, at the reserve. The results from this study showed that about 40% of the total area of the Dongtan Reserve contained suitable habitats for these four bird families. The Scirpus mariqueter zone, mudflat zone, and tidal creeks were the most important habitats for these birds. This study indicated the potential of this approach for objective and effective evaluation of the species habitat suitability in a dynamic estuarine and coastal area. The implications of the results as a tool for biodiversity conservation, wetland conservation, and ecosystem management are discussed.  相似文献   

一种从ERS-1SAR海洋图像中检测船舶航迹的算法   总被引：7，自引：1，他引：6  

周红建  周宗潭  李相迎  王正志  刘雅浪 《遥感学报》2000,4(1):55-60

简单介绍了船舶航迹的几种模式,分析了单纯运用Ｔａｄｏｎ变换方法检测航迹的４个局限,并针对这些局限提出了一种检测航迹的思想－－先进行斑点噪声的抑制,然后用生理视觉的静态轮廓系统对图像进行处理,最后应用Ｒａｄｏｎ变换的方法来突出航迹的线性特征。我们用ＥＲＳ－１ ＳＡＲ海洋图像进行了测试,结果表明这一方法比单纯应用Ｒａｄｏｎ变换的方法更为前效。  相似文献   

Simulating wide-field quasar surveys from the optical to near-infrared     

Natasha Maddox  Paul C. Hewett 《Monthly notices of the Royal Astronomical Society》2006,367(2):717-731

A number of deep, wide-field, near-infrared (NIR) surveys employing new infrared cameras on 4-m class telescopes are about to commence. These surveys have the potential to determine the fraction of luminous dust-obscured quasars that may have eluded surveys undertaken at optical wavelengths. In order to understand the new observations it is essential to make accurate predictions of surface densities and number–redshift relations for unobscured quasars in the NIR based on information from surveys at shorter wavelengths. The accuracy of the predictions depends critically on a number of key components. The commonly used single power-law representation for quasar spectral energy distributions (SEDs) is inadequate and the use of an SED incorporating the upturn in continuum flux at  λ∼ 12 000 Å  is essential. The presence of quasar host galaxies is particularly important over the rest-frame wavelength interval  8000 < λ < 16 000 Å  and we provide an empirical determination of the magnitude distribution of host galaxies using a low-redshift sample of quasars from the Sloan Digital Sky Survey Data Release 3 quasar catalogue. A range of models for the dependence of host galaxy luminosity on quasar luminosity is investigated, along with the implications for the NIR surveys. Even adopting a conservative model for the behaviour of host galaxy luminosity the number counts for shallow surveys in the K band increase by a factor of 2. The degree of morphological selection applied to define candidate quasar samples in the NIR is found to be an important factor in determining the fraction of the quasar population included in such samples.  相似文献