首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
From a dataset of macrobenthos obtained from 18 cruises from 2004 to 2013 in the Huanghe(Yellow River)Estuary and its adjacent areas,the composition and characteristics of macrobenthos were analyzed,and the applicability of the Shannon-Wiener Index(H′),AZTI's Marine Biotic Index(AMBI) and multivariate AMBI(MAMBI) for assessing benthic habitat quality was compared.The results showed a total of 203 macrobenthos in the study area.The macrobenthos were dominated by polychaetes,followed by mollusks and crustaceans.The macrobenthic ecological groups were dominated by EGI,EGII and EGIII,which respectively accounted for 31.5%,36.0% and 21.2% of the total.There were significant differences between the evaluation results of the three indices.The ecological quality status(EQS) levels given by the AMBI were greater than those given by the H′ and M-AMBI.The AMBI could not reflect the differences between 11 sites but the H′ and M-AMBI could do.Moreover,the three indices responded well to the variations in salinity(S) and dissolved oxygen(DO) in the waters.The H′ and MAMBI also responded sensitively to the differences in physical parameters,such as water depth and sediment texture.The correlation between M-AMBI and environmental pressure gradient data was the strongest.The MAMBI could effectively distinguish degraded conditions from undegraded but the H′ and AMBI could not.Therefore,the M-AMBI reflected benthic habitat health well in the study areas.However,the objectivity of evaluation results of M-AMBI needs further verification by physical,chemical and biological methods.The thresholds also need further discussion.  相似文献   

2.
Analysis of high-resolution seismic reflection profiles and sediment samples has revealed the evolution and sediment budget of the southeastern Yellow Sea mud belt (SEYSM) along the southwestern Korean Peninsula. The SEYSM, up to 50 m thick, over 250 km long and 20–55 km wide, can be divided into three stratigraphic units (A1, A2, and B, from oldest to youngest). Unit A1, overlying the acoustic basement, comprises the northern part of the SEYSM. Unit A2 comprises the southern part of the SEYSM; much of unit A2 is exposed at the seafloor. Unit B completely covers unit A1 and pinches out southward.

14C data suggest that evolution of each unit is closely related to the postglacial sea-level changes. Unit A1 consists of estuarine/deltaic or shallow-water muds deposited during the early to middle stage of postglacial sea-level rise (ca. 14,000–7000 yr B.P.). Unit A2 corresponds to relict muds deposited during the last, deceleration stage of sea-level rise (ca. 7000–3.500 yr B.P.). Unit B consists of shelf muds deposited during the recent sea-level highstand (ca. <3500 yr B.P.).

Very low background activities of 210Pb of the surface sediment of unit A2 suggest that the present-day sediment accumulation is negligible in the southern SEYSM. On the other hand, 210Pb excess activity profiles in unit B yield an average sediment accumulation rate of 3.9 mm/yr, indicating active sediment accumulation in the northern SEYSM. The annual sink (3.0×107 tons/yr) of fine-grained sediment in unit B is about an order of magnitude greater than can be explained by the sediment input from the Korean rivers alone. We propose that reworking of unit A2 has provided large volumes of muds to unit B, resulting in excessive sediment accumulation in the northern SEYSM. Much of unit A2, in turn, is likely to have originated from erosion of unit A1 in the north. This rather unique erosional/depositional regime of the SEYSM is probably owing to the tidal and regional currents characteristic in the southeastern Yellow Sea.  相似文献   


3.
As an important part of the Bohai economic rim, the Laizhou Bay has been stressed by serious eco-environmental problems in recent years. In this study, the Shannon-Wiener index(H′), AZTI's marine biotic index(AMBI) and the multivariate AMBI(M-AMBI) were used to assess the ecological quality status(EQS) of the Laizhou Bay according to macrobenthos data collected annually in August 2011–2014. The results showed that the overall benthic habitat quality in the Laizhou Bay was assessed as "Good". However, 25% of the samples were classified as"Moderate", "Bad" or "Poor" status under degraded conditions. Ecological group Ⅲ(EGⅢ) species which had a certain tolerance to environmental disturbances had a higher proportion in each station, and most of them had appeared the pollution indicator species Capitella capitata. This indicated that the benthic habitat in the Laizhou Bay had been disturbed and polluted to some extent. The comparison of the three indices evaluation result and the RDA analysis showed that the H′ and M-AMBI were more suitable when the relative abundance of the single species was high and the macrobenthic community was significantly imbalanced; when the relative abundance of opportunistic species(EGIV and EGV) was high, the AMBI and M-AMBI could reflected the EQS objectively; in an undisturbed and polluted environment, all the three indices could indicate the benthic habitats quality. In summary, the better correlation between the three indices and environmental factors showed that they were well responsive to the tendency of the benthic habitats quality in the Laizhou Bay.  相似文献   

4.
An integration of sediment physical, chemical, biological, and toxicity data is necessary for a meaningful interpretation of the complex sediment conditions in the marine environment. Assessment of benthic community is a vital component for that interpretation, yet their evaluation is complex and requires a large expenditure of time and funds. Thus, there is a need for new tools that are less expensive and more understandable for managers. This paper presents a benthic biotope index to predict from physical and chemical variables the occurrence of macrobenthic habitats. Parameters such as sediment type, organic matter, depth, and hydrodynamic parameters were selected, through a discriminant analysis, to compute the index. Other authors have used multivariate methods to determine the benthic biotopes for Sado Estuary. The index proved to be a valid tool to classify and assess the spatial patterns of benthic habitat and to synthesize stress biotope gradients.  相似文献   

5.
In this paper, a time-dependent dynamic equation for the potential energy anomaly, , is rigorously derived from dynamic equations for potential temperature and salinity, the continuity equation and the equation of state for sea water. The terms locally changing are (A) the -advection, (B) the depth-mean straining, (C) the non-mean straining, (D) the vertical advection, (E) the vertical mixing, (F) surface and bottom density fluxes, (G) inner sources of density e.g. due to absorption of solar radiation and the non-linearity of the equation of state, and (H) horizontal divergence of horizontal turbulent density fluxes. In order to derive the equation in concise form, a vertical velocity (linearly varying with depth) with respect to depth-proportional vertical coordinates had to be defined. The evaluation of the terms in the -equation is then carried out for a one-dimensional tidal straining study and a two-dimensional estuarine circulation study. Comparisons to empirical estimates for these terms are made for the one-dimensional study. It is concluded that the -equation provides a general reference for empirical bulk parameterisations of stratification and mixing processes in estuaries and coastal seas and that it is a tool for complete analysis of the relevant terms from numerical models.  相似文献   

6.
Acute sediment toxicity tests do not test key life stage events such as moulting and reproduction and therefore do not reveal the longer-term effects of contaminant exposure. A laboratory method is described for determining the chronic toxicity of contaminants associated with whole sediments. The test is conducted using neonates of the estuarine amphipod Corophium volutator at 15 degrees C, salinity 25 psu and a 12 h light:12 h dark photoperiod. The endpoints are survival and growth after 28 days and survival, growth and reproduction of amphipods upon termination of test i.e. reproduction within all control vessels (ca 75 days). The sediment chronic toxicity test was used to investigate the effects of sediments spiked with environmentally relevant preparations of slightly weathered Alaskan North Slope crude oil, including a water-accommodated-fraction (WAF) and a chemically-dispersed (Corexit 9527) WAF. Sediment oil concentrations were quantified using ultra-violet fluorescence. The amphipods exposed to chemically dispersed oil had higher mortality and lower growth rates than control-, Corexit 9527- and WAF-exposed organisms, resulting in reduced reproduction. The described method supplements the standard acute sediment test and would be particularly useful when long-term ecological effects are suspected but acute tests reveal no significant mortality. The sediment chronic test reported herein has shown that sediment that was not evidently toxic during 10-day acute tests could have population-level effects on sediment-dwelling amphipods.  相似文献   

7.
Mapping surveys of coastal benthic habitat in Qeshm Island Geopark, Persian Gulf, were conducted using a combination of biological, sedimentological and echo‐sounding data. The survey area covered approximately 233 km2 in a depth range of 5–25 m, and the data were acquired from a single beam echo sounder, grab, video and still photography. Sediment and macrofauna samples were collected by grab at 76 stations and subjected to classification and ordination analyses. Two acoustic classes were identified differentiating along the near/offshore axis. Sediment texture was dominated by fine grain sizes, with five distinct sub‐sediment types. In total, 214 macrobenthic taxa were identified, of which polychaetes accounted for 60%. Other dominant groups included young sponges, nematodes, malacostracan crustacean, bivalves, ostracods and ophiuroids. Underwater videos and still photos integrated the macrofaunal and sedimentary data and revealed a range of biogenic sedimentary features such as burrows and tubes. The biological data identified six main biological assemblages showing an inshore/offshore pattern. The macrobenthic abundance did not demonstrate a significant difference with depth, although polychaetes were positively correlated with depth. The highest abundance and species richness were observed at median depths. Species distribution and diversity did not show any correlation with sediment type. A preliminary habitat mapping of the south coast of the Qeshm Island Geopark has been carried out, integrating acoustic, sediment and biological data.  相似文献   

8.
In this study, the 14N:15N ratio of suspended particulate material collected from the Tamar river estuary, south-west England, is described. Three populations of particles, distinguishable by their 15N content, were observed. This investigation has shown that populations of estuarine particles are generated by biological transformations in situ and that the 15N content of estuarine particles does not merely reflect hydrodynamic mixing of the freshwater and seawater source particulate material.  相似文献   

9.
The effects of sediment-bound contaminants on kidney and gill chloride cells were surveyed in juvenile Solea senegalensis exposed to fresh sediments collected from three distinct sites of the Sado Estuary (Portugal) in a 28-day laboratorial assay. Sediments were analyzed for metallic contaminants, polycyclic aromatic hydrocarbons and organochlorines as well as for total organic matter, redox potential and fine fraction. The potential for causing adverse biological effects of each surveyed sediment was assessed by comparison of contaminant levels to available guidelines for coastal sediments, namely the Threshold Effects Level (TEL) and the Probable Effects Level (PEL). The Sediment Quality Guideline Quotient indices (SQGQ) were calculated to compare the overall contamination levels of the three stations. A qualitative approach was employed to analyze the histo/cytopathological traits in gill chloride cells and body kidney of fish exposed to each tested sediment for 0, 14 and 28 days. The results showed that sediment contamination can be considered low to moderate and that the least contaminated sediment (from a reference site, with the lowest SQGQ) caused lesser changes in the surveyed organs. However, the most contaminated sediment (by both metallic and organic xenobiotics, with highest SQGQ) was neither responsible for the highest mortality nor for the most pronounced lesions. Exposure to the sediment presenting an intermediate SQGQ, essentially contaminated by organic compounds, caused the highest mortality (48%) and the most severe damage to kidneys, up to full renal necrosis. Chloride cell alterations were similar in fish exposed to the two most contaminated sediments and consisted of a pronounced cellular hypertrophy, likely involving fluid retention and loss of mitochondria. It can be concluded that sediment contamination considered to be low or moderate may be responsible for severe injury to cells and parenchyma involved in the maintenance of osmotic balance, contributing for the high mortality levels observed. The results suggest that sediment-bound organic contaminants such as PAHs (polycyclic aromatic hydrocarbons) and PCBs (polychlorinated biphenyls) may be very toxic to the analyzed organs, especially the kidney, even when present in low-risk concentrations.  相似文献   

10.
Concentrations of mercury were determined for the waters, suspended matter and sediments of the Tagus and of major French estuaries.The Tagus estuary is one of the most contaminated by mercury derived from the outfalls of a chloralkali plant and from other industrial sources. In deposited sediments the median level, 1·0 μg Hg g?1, is twenty times higher than the natural background and Hg contents depend on the sediment grain-size, age and the distance from waste-outfalls. Suspended matter is more regularly and highly contaminated (median value: 4·5 μg Hg g?1). In the French estuaries Hg levels in the suspended material decrease with salinity due to dilution and/or remobilization processes. In June 1982, in the Loire estuary, high values of Hg are observed in the middle estuary and attributed to urban and industrial sources.In the Tagus estuary, the general distribution of total dissolved Hg confirms the contamination: it increases seaward from 10 ng 1?1 in the river to 80 ng 1?1 in the estuary outlet. The dissolved Hg is almost totally organic in the river, inorganic in the middle estuary due to inorganic Hg effluents and again organic in the lower estuary. This variation is related to the dissolved organic carbon values. The dissolved Hg levels in the Loire Estuary (5–300 ng 1?1) are much higher than in the Gironde estuary (3–6 ng 1?1) and of the same order as those observed in the Tagus estuary.  相似文献   

11.
Down-core sediment pigment concentrations from four Northern European estuaries were measured using high-performance liquid chromatography (HPLC) to investigate phytoplankton community structure and preservation conditions over the last ca. 100 years where all sites have experienced different levels of eutrophication. Phytoplankton pigments have been shown to be useful biomarkers for phytoplankton community structure and abundance due to their taxonomic specificity. The pigment concentrations and sediment pigment inventory showed large variation between the four sites. Concentrations ranged from more than 6000 nmol/g OC to less than 100 nmol/g OC and the inventory integrated over the top 10 cm from more than 300 nmol/cm2 to less than 30 nmol/cm2 for total identified pigments. Good pigment preservation in Mariager Fjord (Denmark) reflected the almost permanently anoxic conditions. Pigments in Laajalahti (Finland) showed peak concentrations around the time of highest nitrogen loading events known from historical and modelled records over the past 100 years. In contrast, poor down-core preservation of pigments (especially carotenoids) was observed in the Ems-Dollard (The Netherlands) and Himmerfjärden (Sweden) estuaries. The Ems-Dollard site is an intertidal mudflat that experiences daily exposure to light and air, which enhances pigment degradation. In Himmerfjärden, resuspension is an important process affecting both the sedimentation rate and degradation properties. The different preservation conditions at the four sites were supported by the differences in two degradation indicators; the ratio of pheopigment-a to chlorophyll-a and total carotenoids to total pigments. Class-specific carotenoid pigments represented the dominant algal groups reported from each site, however, no distinct down-core changes in the pigment composition were observed at any of the four sites. This indicated that changes in plankton community structure on the group level have been limited over this time period or masked by low preservation of pigments.  相似文献   

12.
We propose a coherent regression model building framework to construct fish-based indices. More specifically, we concentrate on the selection of an optimal set of metrics which remains a difficult problem. The paper departs from the observation that an index of biotic integrity (IBI) is analogous to a diagnostic model in medicine assessing the health condition of a patient from a series of biomarkers. In the same vein, an IBI is a diagnostic model predicting the ecosystem condition of a site from a set of (scored) metrics. Metrics are community attributes sensitive to anthropogenic pressure and their scores express the “distance to target” to a reference condition. In a medical context, Receiver Operating Characteristic (ROC) curves are commonly used to assess the diagnostic accuracy of laboratory tests. An ROC curve plots the sensitivity of a test (Se; the capacity to detect a disease or degradation) as a function of its false positive fraction (FPF) which is the complement of the specificity (Sp = 1 - FPF; the capacity to recognise a healthy person or a reference condition). The ROC curve represents the strength of the index to discriminate between degraded and reference sites. Higher curves correspond to stronger tests as then a higher sensitivity can be combined with a lower false positive fraction. Hence, it is intuitively clear to use summary statistics of the ROC curve as criteria to optimise medical tests or biotic indices. In this paper, we illustrate the value of this modelling framework with a case study in the Zeeschelde estuary in Belgium. In essence, a “traditional” IBI is an average of metrics scoring relevant properties of the ecosystem. We demonstrate this average score model (AVG) is a special member of the more flexible predictive logistic model (PLM) family. The selection of a set of metrics becomes equivalent to variable selection in statistical model building. We apply model building techniques as best subsets regression to facilitate the search for an optimal suite of metrics from a candidate set and use cross-validation to avoid overfitting. The results show that a few metrics suffice to discriminate between most-impacted and least-impacted sites.  相似文献   

13.
The Pentland Firth, located between the north coast of mainland Scotland (UK) and the Orkney Islands, is recognised as an excellent location for the utilisation of tidal stream technology. Potential ecological impacts associated with tidal stream technology may ultimately depend on device design, array size and deployment location. Available ecological data for the Pentland Firth is summarised and strategic priorities for assessing ecological impacts are provided. Baseline data on marine species and habitats in the Pentland Firth is severely lacking and consequently the integrity of any environmental impact assessment could be compromised by this lack of data.  相似文献   

14.
最大熵模型(Maximum Entropy Model,Maxent)和栖息地指数(Habitat Suitability Index,HSI)模型均广泛应用于渔情预报研究中。为比较两模型渔情预报效果以提升日本鲭(Scomber japonicus)资源的科学管理水平,本研究利用2003−2012年东、黄海日本鲭的渔业数据以及海表温度、海面高度、海表盐度、海表温度梯度等海洋环境数据,构建最大熵模型和HSI模型,以分析、比较两模型对东、黄海日本鲭栖息地的预测效果,并利用受试者工作特征(Receiver Operating Characteristic,ROC)曲线下面积(Area Under Curve,AUC)、模型预测的渔场概率与实际渔获量百分比之间的对应关系对两模型渔情预报效果进行了定量评价。结果表明:(1)最大熵模型预测的渔场发生高概率位置与捕捞位置基本重合,在无历史捕捞数据海域预测渔场发生的概率较低;HSI模型预测的高栖息地指数位置与捕捞位置部分重合,在无历史捕捞数据海域也可获得较高的栖息地指数,将非渔场预测为渔场的概率较高;(2)最大熵模型和HSI模型的月平均AUC值分别为0.95和0.66,故最大熵模型的预测结果相对较好;(3)使用HSI模型时,应在模型中加入非渔场数据,并加强对此类数据的收集,否则该类模型预报渔场时有扩大化的可能;使用最大熵模型时,必须提高渔业数据的空间覆盖率,否则无法全面反映渔场时空分布动态。本文研究结果可为提升东、黄海日本鲭渔情预报精度提供参考。  相似文献   

15.
为了量化比较海表层环境及温跃层环境对南太平洋长鳍金枪鱼渔场分布的影响程度;本研究采用2010-2012年南太平洋长鳍金枪鱼延绳钓渔船实际生产统计数据;结合卫星遥感所获取的海表面温度(sea surface temperature;SST)和海表面高度(sea surface height;SSH)数据以及Argo浮标所获取的温跃层上、下界水温和深度数据;运用外包络法分别构建了基于海表层环境变量、温跃层上界环境变量以及温跃层下界环境变量的3种栖息地适应性指数(habitat suitability index;HSI)模型。模型验证结果显示;基于海表层环境变量的HSI模型;HSI>0.6时所占产量比重为70.04%;投钩数量比重为70.86%;HSI>0.8时所占产量比重为24.92%;投钩数量比重为25.79%;基于温跃层上界环境变量的HSI模型;HSI>0.6时所占产量比重为82.17%;投钩数量比重为80.95%;HSI>0.8时所占产量比重为33.24%;投钩数量比重为32.69%;基于温跃层下界环境变量的HSI模型;HSI>0.6时所占产量比重为81.01%;投钩数量比重为81.54%;HSI>0.8时所占产量比重为43.51%;投钩数量比重为43.73%。研究发现;基于温跃层上界和下界环境变量的两个HSI模型预报精度明显高于基于表层环境变量的HSI模型;且基于温跃层下界环境变量的HSI模型预报精度高于基于温跃层上界环境变量的HSI模型。研究结果表明;相较于海表层环境;温跃层环境;尤其是温跃层下界环境特征对南太平洋长鳍金枪鱼资源分布的影响更为显著。  相似文献   

16.
河口季节性缺氧在沉积物中记录的研究进展   总被引:3,自引:0,他引:3  
综述了用分子地层学方法反演河口缺氧及富营养化发生与发展的研究进展,对可追溯缺氧发生的时间及变化趋势、表征人类活动对缺氧的影响的表征的参数的研究进展进行了分析。研究表明:美国河口缺氧事件的发生可追溯到上世纪中期,自70年代起也呈愈演愈烈的发展趋势。沿海人口的增加及人类活动的加剧导致了营养物质输入的增加,再加上全球变暖的趋势,河口区域缺氧将朝更加严重的方向发展,为此需要采取必要措施,通过减少营养物质尤其是硝酸盐的输入来减缓缺氧。  相似文献   

17.
不同环境因子权重对东海鲐鱼栖息地模型的影响研究   总被引:3,自引:1,他引:3  
易炜  郭爱  陈新军 《海洋学报》2017,39(12):90-97
鲐鱼(Scomber japonicus)是栖息在西太平洋沿岸的中上层鱼类,了解其栖息地分布及其与海洋环境因子的关系有助于合理开发和管理该资源。本文根据2003-2011年7-9月中国东海鲐鱼的生产数据,采用正态分布函数分别构建海表面温度(sea surface temperature,SST)、海表温梯度(gradient of sea surface temperature,GSST)和海表面高度(sea surface height,SSH)与作业次数的适应性指数(suitability index,SI),基于不同权重的算术平均法(arithmetic weighted model,AWM)分别建立栖息地指数(habitat suitability index,HSI)模型,并用2012年7-9月生产数据进行验证。结果显示,7、8、9月各月最佳HSI模型的SST、STG和SSH的权重分别为0.5、0.25、0.25,0.8、0.1、0.1和0、1.0、0,利用2012年7-9月生产数据与环境数据对各月份最佳权重HSI模型进行验证,在HSI>0.6的海域,7、8、9月各月作业次数比重和产量比重分别为85.87%和92.55%,76.74%和86.69%,51.83%和56.11%。研究表明,不同月份的环境因子对鲐鱼渔场分布的影响程度不同,本研究为更好地预测鲐鱼栖息地奠定了基础。  相似文献   

18.
细粒酒精模型冰物理力学性质评价的新指标   总被引:1,自引:0,他引:1  
依据酒精细粒模型冰制冰过程中的物理本质和控制细粒酒精模型冰物理力学性质的物理本质,建立了一项适合于喷雾技术细粒模型冰性质评价综合指标.阐明了这一评价指标的物理意义,并给出这一指标与细粒酒精模型冰物理力学性质参数的关系.  相似文献   

19.
The quality of environmental data and its possible impact on the marine species habitat modelling are often overlooked while the sources for these data are increasing. This study selected sea surface temperature(SST) from two commonly used sources, the NOAA Ocean Watch and IRI/LDEO Climate Data Library, and then constructed habitat suitability index model to evaluate the influences of SST from the two sources on the outcomes of Ommastrephes bartramii habitat models for the months of July–October...  相似文献   

20.
为明确东海中鹿岛生态养殖区水质现状,于2017年6月对该海区开展了水质调查,结果表明,中鹿岛海区NH_4~+-N含量、NO_2~--N和NO_3~--N含量的总和、PO_4~(3-)-P含量、pH、盐度和温度的最大值分别为0. 395±0. 011、0. 016±0. 001、0. 029±0. 000 mg/dm~3、8. 21±0. 00、32. 53±0. 05、25. 07±0. 16℃。选取改进内梅罗指数对中鹿岛海区水质进行评价,结果表明,该海区整体水质较为清洁,海区内侧水质水平分布差异显著(p 0. 05),存在明显的分块,其原因可能是由水产养殖活动分布格局引起;对改进内梅罗指数进行水层间方差分析的置换检验表明,改进内梅罗指数在水层间差异不显著(p 0. 05),间接说明海区水体垂向交换能力较强,有利于底部营养物质的交换,对于天然饵料的生长较为有利。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号