Sediment mixed layer as a proxy for benthic ecosystem process and function
Sediment mixed layer as a proxy for benthic ecosystem process and function
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沉积物混合层作为底栖生态系统过程和功能的代表
DOI：
10.3354/meps08736
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发表时间：
2010
影响因子：
2.5
通讯作者：
M. Solan
中科院分区：
文献类型：
--
作者：
L. Teal;E. R. Parker;M. Solan
动物群介导的颗粒和孔隙水混合(生物扰动)改变了表层沉淀层的结构，形成了一个明显的混合层，在那里发生了大部分有机物的降解。目前评估底栖生物栖息地质量的方法通常将这种混合层作为底栖生物活动的指标。虽然人们致力于将大型无脊椎动物的活动与混合深度联系起来，但对定义混合深度在生态系统过程和功能方面所代表的意义的关注较少。本文利用灰度级强度分析方法对现场沉积物剖面图像进行分析，以区分混合带，并将其与物理化学环境联系起来，以确定对其形成影响最大的生物、化学和物理变量。混合层内的生物地球化学条件与下伏的历史沉积层之间存在显著差异。这归因于环境变量(铁、锰、硅、叶绿素a和硝酸根)的组合，而不是单一的主导变化驱动因素。虽然这些发现在多个地点是一致的，但影响混合层深度的驱动因素(S)是因地点和季节而异的。因此，混合深度提供了底栖生态系统功能的合理近似值，但当考虑生态系统过程时，混合深度与其驱动因素(动物群混合、食物投入、环境条件)之间的联系高度依赖于背景。因此，关于底栖生物群落动态和生态系统过程的结论，包括对生境质量的评估，不能仅从混合深度的估计中得出。
Faunal mediated particle and porewater mixing (bioturbation) alters the structure of the surface sediment layer, forming a distinct mixed layer, where the majority of organic matter degradation takes place. Current methods of assessing benthic habitat quality often reference this mixed layer as an indicator of benthic activity. Whilst a great deal of effort has been devoted to linking macro-invertebrate activity to the mixing depth, less attention has been given to defining what the mixing depth represents in terms of ecosystem process and function. Here, in situ sediment profile images are analysed using grey scale intensity analysis to distinguish the mixed zone and relate it to the physicochemical environment in order to determine the biological, chemical and physical variables most influential in its formation. Significant differences were found between biogeochemical conditions within the mixed layer relative to the underlying historic sediment layer. These were attributed to a combination of environmental variables (Fe, Mn, Si, chlorophyll a and NO3–) rather than a single dominant driver of change. Although these findings are consistent across multiple locations, the driver(s) that influence the depth of the mixed layer are site- and season-specific. The mixing depth thus provides a reasonable approximation of benthic ecosystem functioning, but when considering ecosystem process the link between the mixing depth and its driving factors (faunal mixing, food input, environmental conditions) is highly context-dependent. Conclusions on benthic community dynamics and ecosystem process, including assessments of habitat quality, cannot therefore be drawn from estimates of the mixing depth alone.