Department of Environmental Sciences, University of California, Riverside, CA 92521, USA.
Water Res. 2011 Nov 1;45(17):5419-27. doi: 10.1016/j.watres.2011.08.018. Epub 2011 Aug 27.
Quagga mussels (Dreissena bugensis) have been linked to oligotrophication of lakes, alteration of aquatic food webs, and fouling of infrastructure associated with water supply and power generation, causing potentially billions of dollars in direct and indirect damages. Understanding their abundance and distribution is key in slowing their advance, assessing their potential impacts, and evaluating effectiveness of control strategies. Volume backscatter strength (Sv) measurements at 201- and 430-kHz were compared with quagga mussel veliger and zooplankton abundances determined from samples collected using a Wisconsin closing net from the Copper Basin Reservoir on the Colorado River Aqueduct. The plankton within the lower portion of the water column (>18 m depth) was strongly dominated by D-shaped quagga mussel veligers, comprising up to 95-99% of the community, and allowed direct empirical measurement of their mean backscattering cross-section. The upper 0-18 m of the water column contained a smaller relative proportion of veligers based upon net sampling. The difference in mean volume backscatter strength at these two frequencies was found to decrease with decreasing zooplankton abundance (r(2) = 0.94), allowing for correction of Sv due to the contribution of zooplankton and the determination of veliger abundance in the reservoir. Hydroacoustic measurements revealed veligers were often present at high abundances (up to 100-200 ind L(-1)) in a thin 1-2 m layer at the thermocline, with considerable patchiness in their distribution observed along a 700 m transect on the reservoir. Under suitable conditions, hydroacoustic measurements can rapidly provide detailed information on the abundance and distribution of quagga mussel veligers over large areas with high horizontal and vertical resolution.
斑马贻贝（Dreissena bugensis）与湖泊贫营养化、水生食物网的改变以及与供水和发电相关的基础设施的污垢有关，造成了潜在的数十亿美元的直接和间接损失。了解它们的丰度和分布是减缓其蔓延、评估其潜在影响以及评估控制策略有效性的关键。在科罗拉多河渡槽的铜盆水库，用威斯康星闭网器采集样本，对比 201kHz 和 430kHz 体积反向散射强度（Sv）测量值与斑马贻贝幼虫和浮游动物丰度。水柱下部（>18 米深度）的浮游动物主要由 D 形斑马贻贝幼虫组成，占群落的 95-99%，可以直接对其平均反向散射截面积进行实测。根据网采样本，水柱上部（0-18 米）的幼虫比例相对较小。发现这两个频率的平均体积反向散射强度的差异随着浮游动物丰度的降低而减小（r(2) = 0.94），从而可以对由于浮游动物的贡献而导致的 Sv 进行修正，并确定水库中幼虫的丰度。水声学测量表明，幼虫在温跃层附近的一层 1-2 米厚的薄水层中经常以高丰度（高达 100-200 个 ind L(-1)）存在，在水库 700 米长的横截面上观察到其分布存在相当大的斑块性。在合适的条件下，水声学测量可以快速提供有关斑马贻贝幼虫丰度和分布的详细信息，具有高水平和垂直分辨率，覆盖大面积。
