Resacas of the lower Rio Grande River (secondary channels, distributaries, oxbow lakes) are vital freshwater wetlands under intense anthropogenic pressure. Many of these wetlands have their water levels tightly managed and some are being restored. Reliable bioassessment methods to effectively discriminate among resacas of differing ecological status are needed. Common components of bioassessments for aquatic ecosystems include surveys of biological communities, among which the macroinvertebrates are generally considered the most accurate. The macroinvertebrate community of resacas is virtually undocumented and various sampling methods have never been used in parallel. Here we used two popular sampling techniques (benthic corer and dip net), while producing the first portrait of the macroinvertebrate community inhabiting resacas. Despite sampling different invertebrate assemblage subsets, both methods discriminated among studied resacas in a similar manner; however, the corer presents several advantages including: 1) a much higher precision (based on coefficients of variation), 2) more adequate representation of an indicator species (invasive gastropod), and 3) clearer differences in functional feeding groups among resacas which constitutes an additional indicator metric.

中文翻译：

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来自两种采样方法的大型无脊椎动物组合类似地区分了德克萨斯州南部具有不同生态系统状态的淡水湿地

格兰德河下游的雷萨卡斯（二级河道、支流、牛轭湖）是处于强烈人为压力下的重要淡水湿地。许多湿地的水位受到严格管理，有些正在恢复。需要可靠的生物评估方法来有效区分不同生态状态的 resacas。水生生态系统生物评估的常见组成部分包括生物群落调查，其中大型无脊椎动物通常被认为是最准确的。resacas 的大型无脊椎动物群落几乎没有记录，并且从未同时使用过各种采样方法。在这里，我们使用了两种流行的采样技术（底栖取芯器和浸网），同时制作了居住在 resacas 的大型无脊椎动物群落的第一幅肖像。尽管对不同的无脊椎动物组合子集进行了采样，但这两种方法都以类似的方式区分了研究的 resacas。然而，corer 具有几个优点，包括：1) 更高的精度（基于变异系数），2) 更充分地代表指示物种（侵入性腹足动物），以及 3) 构成 resacas 的功能性喂养组的更明显差异一个额外的指标指标。