ABSTRACT: The Wadden Sea is a highly dynamic tidal system and an important area for a variety of species, including wild and cultivated mussels. Increased suspended sediment concentrations may negatively affect ecosystem functioning across trophic levels; hence, insight into the effects of anthropogenic activities is of importance. The aim of this study was to investigate the scale of sediment resuspension associated with commercial mussel cultivation activities. Turbidity prior to and during fisheries and harvest was investigated by in situ measurements with towed and fixed sensors. Four case studies were selected to represent maximum disturbance. For one case study, sediment resuspension was further investigated by analysis of satellite images. The in situ measurements showed that turbidity is enhanced by mussel fisheries and harvest but that effects are limited in time and space. Turbidity enhancement during fisheries was several-fold higher than that during harvest, whereas the spatial scale of both activities was limited to their direct vicinity. In contrast to the in situ study, the satellite image analysis identified a spatial magnitude that extended over a somewhat larger spatial scale, in the form of a dark water plume, and further revealed that this plume consisted of high concentrations of coloured dissolved organic matter (CDOM), rather than suspended particles. Along with turbidity, CDOM thus seems an important consideration for determining light attenuation in a water body affected by anthropogenic seafloor disturbance. As we presented case studies that were expected to represent maximum impact, we conclude that there is no specific need for further in-depth studies that allow upscaling to ecosystem-wide effects.

中文翻译：

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瓦登海西部贻贝渔业和水产养殖形成的沉积物羽流的时空分析

摘要：瓦登海是一个高度动态的潮汐系统，也是包括野生和养殖贻贝在内的多种物种的重要栖息地。悬浮沉积物浓度增加可能对整个营养级的生态系统功能产生负面影响；因此，深入了解人为活动的影响非常重要。本研究的目的是调查与商业贻贝养殖活动相关的沉积物再悬浮的规模。通过使用拖曳和固定传感器进行现场测量，研究了捕鱼和收获之前和期间的浊度。选择了四个案例研究来代表最大干扰。在一个案例研究中，通过分析卫星图像进一步研究了沉积物再悬浮。就地_测量表明，浊度因贻贝渔业和收获而增加，但这种影响在时间和空间上是有限的。渔业期间的浊度增加比收获期间高几倍，而这两种活动的空间尺度仅限于它们的直接附近。与现场相比研究中，卫星图像分析确定了一个空间幅度，它以暗水羽的形式延伸到更大的空间尺度，并进一步揭示了这个羽流由高浓度的有色溶解有机物 (CDOM) 组成，而不是悬浮粒子。因此，与浊度一起，CDOM 似乎是确定受人为海底干扰影响​​的水体光衰减的重要考虑因素。由于我们介绍了预计会产生最大影响的案例研究，因此我们得出结论，没有特别需要进一步深入研究以扩大对整个生态系统的影响。