Department of Entomology, University of Minnesota, Saint Paul, MN 55108-6125, USA,
Environ Monit Assess. 2011 Oct;181(1-4):205-23. doi: 10.1007/s10661-010-1824-6. Epub 2010 Dec 15.
Community, diversity, and biological index metrics for chironomid surface-floating pupal exuviae (SFPE) were assessed at different subsample sizes and sampling frequencies from wadeable streams in Minnesota (USA). Timed collections of SFPE were made using a biweekly sampling interval in groundwater-dominated (GWD) and surface-water-dominated (SWD) streams. These two types of stream were sampled because they support different Chironomidae communities with different phenologies which could necessitate sampling methodologies specific to each stream type. A subsample size of 300 individuals was sufficient to collect on average 85% of total taxa richness and to estimate most metrics with an error of about 1% relative to 1,000 count samples. SWD streams required larger subsample sizes to achieve similar estimates of taxa richness and metric error compared to GWD streams, but these differences were not large enough to recommend different subsampling methods for these stream types. Analysis of sample timing determined that 97% of emergence occurred from April through September. We recommend in studies where estimation of winter emergence is not important that sampling be limited to this period. Sampling frequency also affected the proportion of the community collected. To maximize the portion of the community, collected samples should be taken across seasons although no specific sampling interval is recommended. Subsampling and sampling frequency was also assessed simultaneously. When using a 300-count subsample, a 4-week sampling interval from April through September was required to collect on average 71% of the community. Due to differences in elements of the chironomid community evaluated by different studies (e.g., biological condition, phenology, and taxonomic composition), richness estimates are documented for five sampling intervals (2, 4, 6, 8, 10, and 12 weeks) and five subsample sizes (100, 200, 300, 500, and 1,000 counts). This research will enhance future studies by providing guidelines for tailoring SFPE methods to study specific goals and resources.
在明尼苏达州（美国）的可涉水溪流中，以不同的子样本大小和采样频率评估了摇蚊表面浮蛹蜕（SFPE）的群落、多样性和生物指数指标。使用地下水主导（GWD）和地表水主导（SWD）溪流的双周采样间隔，对 SFPE 进行了定时采集。选择这两种类型的溪流是因为它们支持不同的摇蚊科群落，具有不同的物候期，这可能需要针对每种溪流类型的特定采样方法。300 个个体的子样本大小足以平均收集 85%的总分类 richness，并以约 1%的相对误差估计大多数指标，而 1000 个计数样本的相对误差为 1%。与 GWD 溪流相比，SWD 溪流需要更大的子样本大小才能达到相似的分类 richness 估计和指标误差，但这些差异不足以推荐用于这两种溪流类型的不同子采样方法。样本时间分析确定，97%的羽化发生在 4 月至 9 月。我们建议，如果不重要估计冬季羽化，那么研究应仅限于此期间进行采样。采样频率也会影响采集到的群落比例。为了最大限度地采集到群落，应在整个季节进行采样，尽管不推荐具体的采样间隔。还同时评估了子采样和采样频率。当使用 300 个计数的子样本时，需要从 4 月到 9 月每隔 4 周进行一次采样，以平均收集 71%的群落。由于不同研究评估的摇蚊群落的元素不同（例如，生物状况、物候期和分类组成），因此记录了五个采样间隔（2、4、6、8 和 10 周）和五个子样本大小（100、200、300、500 和 1000 个计数）的丰富度估计值。本研究通过为根据特定目标和资源调整 SFPE 方法提供指导方针，将增强未来的研究。
