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This study reports the state and causes of eutrophication in the Portuguese continental Exclusive Economic Zone (EEZ), during a 14-year period (1995–2008), following the European Marine Strategy Framework Directive (MSFD) and using the trophic index TRIX for an integrated evaluation of indicators of eutrophication, and identifies areas where monitoring is needed to improve the eutrophication assessment. A non-continuous dataset for the 8 indicators specified by the MSFD for eutrophication assessment was used, including published and grey data. Eutrophication indicators were validated and thresholds reviewed, considering regional differences. The diatom:flagellate ratio was found a poor indicator of eutrophication as shifts in the diatom:flagellate ratio naturally occur associated with alternating water column turbulence and upwelling, and stratification, and therefore, could not be associated with anthropogenic nutrient enrichment effects. Assessment areas were, as a whole, classified as non-problem areas concerning eutrophication. Although nutrient enrichment was observed in coastal waters, related to river plume influence, nutrient enrichment direct and indirect effects were generally not detectable, possibly due to water column dispersion and mixing processes. Only occasionally, mild eutrophication was found in specific areas under the influence of major river (Douro, Vouga and Guadiana) plumes, associated with high nutrient and phytoplankton biomass levels and seagrass decline, which indicates the need for directed monitoring on eutrophication in those areas. 相似文献
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The usefulness of benthic multi-metric indices when assessing seafloor integrity across broad environmental gradients should be deliberated, as their lack of transparency might hide important sources of variation and fail to identify environmental change. This study compares the performance of two multi-metric indices; the Benthic Quality Index (BQI) and the Brackish water Benthic Index (BBI) between three sub-basins in the Baltic Sea. Both indices reflect the salinity-driven gradient in macroinvertebrate diversity and composition as well as changes in bottom water oxygen concentrations. The relative contribution of predictor variables for explaining index variation does, however, differ between sub-basins, resulting in the indices representing different aspects of the benthic community along the environmental gradient. This context-dependency is caused by inherent differences in benthic community characteristics between the sub-basins of the Baltic Sea, and how the communities are portrayed by the indices. An increased transparency of the importance of the different predictors for directing index values is needed for coherent classifications over broad environmental gradients, such as those occurring in large estuarine water bodies. Use of a weight of evidence table to combine multiple indicators would preserve transparency and be more likely to provide a robust assessment method that would detect seafloor degradation at an early stage. 相似文献
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Marco Dogs Bernd Wemheuer Laura Wolter Nils Bergen Rolf Daniel Meinhard Simon Thorsten Brinkhoff 《Systematic and applied microbiology》2017,40(6):370-382
Macroalgae harbour specific microbial communities on their surface that have functions related to host health and defence. In this study, the bacterial biofilm of the marine brown alga Fucus spiralis was investigated using 16S rRNA gene amplicon-based analysis and isolation of bacteria. Rhodobacteraceae (Alphaproteobacteria) were the predominant family constituting 23% of the epibacterial community. At the genus level, Sulfitobacter, Loktanella, Octadecabacter and a previously undescribed cluster were most abundant, and together they comprised 89% of the Rhodobacteraceae. Supported by a specific PCR approach, 23 different Rhodobacteraceae-affiliated strains were isolated from the surface of F. spiralis, which belonged to 12 established and three new genera. For seven strains, closely related sequences were detected in the 16S rRNA gene dataset. Growth experiments with substrates known to be produced by Fucus spp. showed that all of them were consumed by at least three strains, and vitamin B12 was produced by 70% of the isolates. Since growth of F. spiralis depends on B12 supplementation, bacteria may provide the alga with this vitamin. Most strains produced siderophores, which can enhance algal growth under iron-deficient conditions. Inhibiting properties against other bacteria were only observed when F. spiralis material was present in the medium. Thus, the physiological properties of the isolates indicated adaption to an epiphytic lifestyle. 相似文献
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长白山针阔混交林不同演替阶段群落系统发育和功能性状结构 总被引:2,自引:0,他引:2
群落构建一直是生态学研究的热点,基于系统发育和功能性状量化生境过滤、竞争排斥以及随机过程在群落构建中的作用,能够深入理解群落构建机制。本研究以长白山针阔混交林不同演替阶段的3个5.2 hm~2样地(次生杨桦林、次生针阔混交林、原始椴树红松林)为平台,基于被子植物分类系统Ⅲ(Angiosperm Classification System,APGⅢ)构建的系统发育树和7个关键功能性状(叶面积、比叶面积、叶片厚度、叶片氮含量、叶片磷含量、氮磷比、最大树高),结合环境数据,分析不同演替阶段群落系统发育和功能性状结构。研究表明:(1)各演替阶段7个植物功能性状都表现出显著的系统发育信号,表明植物功能性状受系统发育历史影响;(2)系统发育和功能性状结构在不同演替阶段和不同径级均为非随机状态。随着演替的推进群落系统发育和功能性状结构由聚集走向发散;随着径级的增加,系统发育和功能性状结构的聚集程度减小,表明随着演替阶段的进行和径级增大,竞争性排斥的作用逐渐明显;(3)各演替阶段系统发育和功能性状的周转都为非随机且不同因子对两者的解释力度存在差异。演替早期空间距离的解释力度小于环境距离,说明生境过滤在群落构建中的重要性,而在演替后期空间距离的解释力度大于环境距离,验证了扩散限制在群落构建中的重要性。 相似文献
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Climate and land use changes will degrade the configuration of the landscape for titi monkeys in eastern Brazil 下载免费PDF全文
Sidney F. Gouveia João Pedro Souza‐Alves Ludmila Rattis Ricardo Dobrovolski Leandro Jerusalinsky Raone Beltrão‐Mendes Stephen F. Ferrari 《Global Change Biology》2016,22(6):2003-2012
Land use changes have profound effects on populations of Neotropical primates, and ongoing climate change is expected to aggravate this scenario. The titi monkeys from eastern Brazil (Callicebus personatus group) have been particularly affected by this process, with four of the five species now allocated to threatened conservation status categories. Here, we estimate the changes in the distribution of these titi monkeys caused by changes in both climate and land use. We also use demographic‐based, functional landscape metrics to assess the magnitude of the change in landscape conditions for the distribution predicted for each species. We built species distribution models (SDMs) based on maximum entropy for current and future conditions (2070), allowing for different global circulation models and contrasting scenarios of glasshouse gas concentrations. We refined the SDMs using a high‐resolution map of habitat remnants. We then calculated habitat availability and connectivity based on home‐range size and the dispersal limitations of the individual, in the context of a predicted loss of 10% of forest cover in the future. The landscape configuration is predicted to be degraded for all species, regardless of the climatic settings. This include reductions in the total cover of forest remnants, patch size and functional connectivity. As the landscape configuration should deteriorate severely in the future for all species, the prevention of further loss of populations will only be achieved through habitat restoration and reconnection to counteract the negative effects for these and several other co‐occurring species. 相似文献
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