Eelgrass as a Bioindicator Under the European Water Framework Directive
Eelgrass as a Bioindicator Under the European Water Framework Directive
复制标题
鳗草作为欧洲水框架指令下的生物指示剂
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
K. Nielsen
中科院分区：
文献类型：
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作者：
D. Krause‐Jensen;T. M. Greve;K. Nielsen
鳗草是温带沿海沃茨分布最广的植物。它被认为是一个有用的水质指标，因为水的清澈度调节其向更深沃茨的延伸，即深度限制。本研究分析了使用的水草深度限制作为生物指示剂根据水框架指令（WFD）。WFD要求通过将生物指标的实际水平与所谓的“参考水平”相关联来对生态状况进行分类，反映有限的人为影响。该指令进一步要求，参考水平的定义为“水体类型”具有类似的水文形态特征，从而成为“类型特异性”的分类。一个大型的历史数据集的深度限制的鳗草1900年左右被用来确定参考水平，和一个大型的数据集，从丹麦国家监测和评估计划，以确定实际的深度限制。数据代表了广泛的丹麦沿海水体，分为10个水体类型的基础上的盐度和水深的差异，分析清楚地表明，生态状态类的定义显着影响生态状态的评估，根据WFD。此外，该研究表明，使用特定类型的分类意味着误解生态状况的风险。尽管有关于参照条件的独特数据材料，但分类问题仍然突出，在参照条件定义不明确的情况下，问题可能更大。在个别地点的分类中，采用个别地点的参考水平，可获得更稳健的分类。总括而言，当根据水草的深度限制对水质进行分类时，如有有关资料，建议采用个别地点的参考水平。如果使用关于参考水平的更一般性资料，则必须考虑到已知会影响深度限值的当地条件。
Eelgrass is the most widespread plant in temperate coastal waters. It is regarded as a useful indicator of water quality because water clarity regulates its extension towards deeper waters, i.e. the depth limit. This study analyses the use of eelgrass depth limits as a bioindicator under the Water Framework Directive (WFD). The WFD demands that ecological status is classified by relating the actual level of bioindicators to a so-called ‘reference level’, reflecting a situation of limited anthropogenic influence. The directive further demands that reference levels are defined for ‘water body types’ with similar hydromorphological characteristics, and that the classification thereby becomes ‘type-specific’.A large historic data set on depth limits of eelgrass around 1900 was used to characterise reference levels, and a large data set from the Danish National Monitoring and Assessment Programme to characterise actual depth limits. Data represented a wide range of Danish coastal water bodies that were grouped into 10 water body types based on differences in salinity and water depth.The analyses clearly illustrate that the definition of ecological status classes markedly influence the assessment of ecological status according to the WFD. Moreover, the study demonstrates that the use of type-specific classification implies a risk of misinterpreting ecological status. Classification problems were pronounced in spite of a unique data material on reference conditions, and the problems are likely to be even greater in cases where reference conditions are less well defined. A more robust classification was obtained by using reference levels for individual sites in a site-specific classification.In conclusion, when classifying water quality on the basis of eelgrass depth limits, site-specific reference levels are recommended if such data are available. If more general information on reference levels is used, local conditions known to affect depth limits must be taken into account.