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991.
Cristina Munari Elena Manini Antonio Pusceddu Roberto Danovaro & Michele Mistri 《Marine Ecology》2009,30(2):255-268
The European Water Framework Directive (WFD, 2000/60/EC) recommends the development of biotic indices for assessing the ecological quality status of water bodies. The Benthic Index based on Taxonomic Sufficiency (BITS) was specifically developed for lagoonal systems, according to the tolerant/opportunistic approach. Macrobenthic data, variables indicative of eutrophication and variables indicative of sedimentary organic matter quality were collected during 18 surveys carried out between 2004 and 2005 in three Adriatic coastal lagoons (Venice Lagoon, Sacca di Goro, Lesina Lagoon). The relationship between environmental variables and biotic indices (AMBI, BENTIX, BITS, BOPA and FINE) was tested using multivariate analyses. Indices based on species classification level appeared to relate better with the variables describing organic matter quality, whereas BITS, which is based on family classification level, seemed related to eutrophication indicative variables, such as sulphide, ammonium, dissolved oxygen and orthophosphate concentrations. The BITS approach reduces the costs associated with sorting and identification of organisms. Providing a rapid assessment of ecological quality, and producing an ecologically relevant classification, BITS seems a promising tool for monitoring programs of Adriatic lagoonal ecosystems. Its sensitivity in reflecting the field conditions elsewhere, however, remains to be assessed. 相似文献
992.
The day–night cycle is one of the strongest geophysical cycles modulating species' behavioral rhythms. However, in deep-water continental margins, where light intensity decreases over depth, interspecific competition may alter behavioral responses to day–night cycles. The burrowing decapod crustacean Nephrops norvegicus is a large-size predator in benthic communities, exerting despotic territorial behavior. In this study, we analysed how the effect of light intensity cycles on decapod behavioral rhythms is reduced as one moves from shelves to slopes. In the Western Mediterranean, the predatory behavior and interspecific competition for substrate use of Nephrops increases moving from the shelf (100–110 m) to the slope (400–430 m). Vector fitting and generalized additive models were used to assess the effect of light intensity and behavioral rhythms of N. norvegicus on the temporal variation of prey decapods co-occurring in trawl tow catches carried out on the shelf and the slope during October 1999 and June 2000. The combination of diel variations in light intensity and N. norvegicus abundance influences the activity rhythms of prey decapods in a depth- and seasonal-dependent manner. Light modulation is stronger on the shelf and weaker on the slope, where Nephrops population size is greater. Although present regression analysis does not necessarily imply a direct cause–effect relationship between rhythms of predators and prey, we suggest that Nephrops alters the temporal patterning in the behavior of its prey on the slope, where light intensity is reduced. This alteration is stronger in endobenthic species than in benthopelagic species; the former rely on bottom substrate for the expression of behavioral rhythms, experiencing stronger interspecific competitions with Nephrops at time of activity. 相似文献
993.
The overall effects of trawling on benthic habitats and their assemblages are dependent on the distribution and intensity of trawl effort. The benthic habitats of the Spencer Gulf prawn trawling grounds are subjected to known variable levels of trawling disturbance recorded from fisher's logbooks. These habitats have not been quantitatively investigated. The aim of the study was firstly to characterise the macro-faunal and -floral assemblages and secondly, to comparatively assess trawl impact by testing the null hypothesis of no differences between five sites exposed to different intensity of trawl effort. The distribution and abundance of benthic macro-fauna and -flora were studied at two sampling resolutions by using beam trawl sampling (10,000 m2) and underwater stereophotography (4.5 m2) at five sites with different levels of trawl disturbance (effort). The results showed that the Spencer Gulf prawn trawling grounds are characterised by sandy sediments with a low content of silt and clay, with the exception of one site with very fine gravel. Biomass, abundance and cover of macro-fauna and -flora were generally low throughout, but with large differences among sites. Biomass, abundance and cover were found to be negatively correlated to both trawl hours from 1994–1998 and during the period of study. ANOSIM and SIMPER analyses using biomass, abundance and percentage cover as variables showed significant differences between sites with eight species or taxonomic groups contributing more than 10% to the observed similarity within sites. The two northern sites were dominated by sponges and the bearded mussel, Trichomya hirsutus, and the southern hammer oyster, Malleus meridianus. Other species that contributed to the similarity within sites were the ascidian, Polycarpa viridis, mobile epifauna (the blue swimmer crab, Portunus pelagicus, and the western king prawn, Penaeus (Melicertus) latisulcatus) and demersal fish species (Degens leatherjacket, Thamnaconus degeni, and the Melbourne silver belly, Parequula melbournensis). Simpson's Index of Diversity (1 − λ) and species richness in the beam trawl samples were fairly even across all sites, but a significant effect of site was found in the stereophotographic transect samples. It was concluded that prawn trawling has a strong influence on the structure of the benthic habitats of the Spencer Gulf prawn fishing grounds highlighted by the magnitude of change and the strength of the gradient of effects. Confounding factors linked to the biophysical attributes of the sites are believed to be minor. 相似文献
994.
Diatom data of 192 surface sediment samples from the marginal seas in the western Pacific together with modern summer and winter sea surface temperature and salinity data were analyzed.The results of canonical correspondence analysis show that summer sea-surface salinity(SSS) is highly positively correlated with winter SSS and so is summer sea-surface temperature(SST) with winter SST.The correlations between SSSs and SSTs are less positively correlated,which may be due to interactions of regional current pa... 相似文献
995.
基于公平性的水环境容量分配研究——以沱江流域为例 总被引:1,自引:0,他引:1
公平与效益是容量分配的两个重要原则.在我国目前采用的水环境容量无偿分配方式下,公平原则是需遵循的首要原则,在公平的基础上追求效益.以沱江流域为对象,综合考虑涉及区域的社会、经济、自然等客观因素,筛选指标确定系数对流域容量进行分配.应用经济学中衡量收入公平的基尼系数概念,对分配结果的公平性进行评估,给出综合体现社会性、经济性和历史性的水环境容量分配方案. 相似文献
996.
西太平洋暖池近3万年来的沉积序列及其环境特征-WP92-3柱样的REE记录 总被引:1,自引:0,他引:1
WP92-3柱样采自西太平洋暖池核心区。利用稀土元素(REE)特征参数研究了该柱样的沉积物来源和地层序列划分,并对其所揭示的环境变化特征进行了探讨。研究认为:样品的REE分布模式揭示了该海域的沉积物源主要为海相自生沉积;基于REE指标的垂向深度变化特征可将该柱样划分为3个地层序列;∑REE,LREE/HREE和δCe几个指标对环境的温度变化以及地磁场的极性变换均有良好的响应,∑REE高值段基本对应于δ18O和SST所揭示的暖池低温期,而地磁场极性转变的时间正好对应着稀土指标(∑REE,LREE/HREE和δCe)快速大幅波动的层位。REE特征参数较好地记录了暖池区近3万年来的沉积和环境变化信息,是一组对气候环境演化具有潜在良好指示作用的地球化学指标。 相似文献
997.
柱撑蛭石吸附去除废水中重金属离子的实验研究 总被引:2,自引:0,他引:2
分别利用有机柱化剂十二烷基磺酸钠(SDS)和无机柱化剂聚羟基铝(HA)对蛭石进行柱撑制得十二烷基磺酸钠柱撑蛭石(SDS-V erm icu lite)和聚羟基铝柱撑蛭石(HA-V erm icu lite),并通过XRD、红外光谱、ZETA电位等表征手段对柱撑蛭石进行表征,同时针对柱撑蛭石对Cu2 ,Cd2 ,C r3 3种重金属离子的吸附进行研究,结果表明:吸附去除率受反应时间、重金属离子的初始浓度、pH值等因素的影响,经柱撑后的蛭石对重金属离子吸附的吸附性能比蛭石原矿要强。柱撑蛭石吸附3种重金属离子的动力学吸附过程可用E lov icb方程和双常数方程进行较好的拟合。 相似文献
998.
999.
基于GIS的攀枝花城市地质环境质量分区评价 总被引:1,自引:0,他引:1
攀枝花是一座典型的矿业城市,随着经济发展,矿山地质环境问题严重.在(GIS)地理信息系统技术的支持下,结合多种地质环境因素对该地区进行了地质环境质量现状分析评价,采用层次分析法建立了评价模型,结果表明区内大部分地区地质环境较好.地质环境差的地方主要分布在各大采矿区,地质灾害较严重.文中除了论述评价要素的识别,重点讨论了评价模型的确立和基于GIS的分析方法,最后对评价结果作了分析. 相似文献
1000.
针对河南省煤矸石的积存现状、煤矸石堆放所造成的环境地质问题及煤矸石的综合利用现状等方面进行了论述,在此基础上,提出了高效、科学综合利用煤矸石的方法和建议.具有一定的理论和实际意义. 相似文献