North Temperate Lakes LTER: Phytoplankton - Trout Lake Area 1984 - 2006

Phytoplankton samples from the seven northern Wisconsin LTER lakes in the Trout Lake area (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes and bog lakes 27-02 [Crystal Bog], and 12-15 [Trout Bog]) are collected six times per year at the deep hole sampling station at the same time as our other limnological sampling is conducted. We use a peristaltic pump and tubing, collecting a separate sample from the epilimnion, metalimnion and hypolimnion for most of the lakes. For 27-2 Bog Lake, which is only 2m deep, we collect one 0-2m composite sample. The samples are preserved with Lugols iodine solution. We create a single hypsometrically pooled composite sample per lake from subsamples of the strata samples. The pooled samples are sent to PhycoTech, Inc., a private lab specializing in phytoplankton analysis, to be made into permanent slide mounts. The slide mounts, 3 slides per sample, are archived at the University of Wisconsin - Madison Zoology Museum Phytoplankton are identified to species using an inverted microscope (Utermohl technique) and are reported as natural unit (i.e., colonies, filaments, or single cells) densities per mL, cell densities per mL, and algal biovolume densities per mL. Multiple entries for the same species on the same date may be due to different variants or vegetative states - (e.g., colonial or attached vs. free cell.) Biovolumes for individual cells of each species are determined during the counting procedure by obtaining cell measurements needed to calculate volumes for geometric solids (e.g., cylinders, spheres, truncated cones) corresponding to actual cell shapes. Biovolume concentrations are then computed by mulitplying the average cell biovolume by the cell densities in the water sample. Note that one million cubicMicrometers of biovolume PerMilliliter of water are equal to a biovolume concentration of one cubicMillimeterPerMilliliter. Assuming a cell density equal to water, a cubicMillimeterPerMilliliter of biovolume converts to a biomass concentration of one milligramPerLiter. Sampling Frequency: 6 samples per year Number of sites: 7本数据集涵盖威斯康星州北部特劳特湖区域7个长期生态研究（Long-Term Ecological Research, LTER）湖泊的浮游植物样本，包括Allequash湖、Big Muskellunge湖、Crystal湖、Sparkling湖、Trout湖，以及沼泽湖27-02（Crystal Bog，水晶沼泽湖）与12-15（Trout Bog，特劳特沼泽湖）。研究人员于每年与其他湖沼学采样同步的6个时间节点，在深孔采样站采集样本。采样时使用蠕动泵（peristaltic pump）及管路，多数湖泊分别从表水层（epilimnion）、斜温层（metalimnion）与底水层（hypolimnion）采集独立样本。针对水深仅2米的27-02沼泽湖，则采集0-2米的混合水样。所有样本均采用鲁哥氏碘液（Lugols iodine solution）进行固定。研究人员从各水层样本的子样品中，按水深分层面积加权合并，为每个湖泊制备1份合并混合样本。将合并后的样本送往专注于浮游植物分析的私营实验室PhyTech, Inc.，制作永久玻片标本；每个样本制备3张玻片，存档于威斯康星大学麦迪逊分校动物学博物馆。浮游植物样本采用倒置显微镜结合乌特莫尔计数法（Utermohl technique）鉴定至物种水平，报告指标包括每毫升自然单元（即群体、丝状体或单个细胞）密度、每毫升细胞密度及每毫升藻类生物体积密度。同一日期同一物种存在多条记录的原因，可能是存在不同变体或营养状态——例如（群体/附着态 vs 游离细胞）。计数过程中，通过测量对应细胞实际形态的几何体（如圆柱体、球体、截头圆锥体）所需参数，计算各物种单个细胞的生物体积；随后以平均细胞生物体积乘以水样中的细胞密度，得到生物体积浓度。请注意：每毫升水中100万立方微米的生物体积，等同于1立方毫米每毫升的生物体积浓度。假设细胞密度与水相当，则1立方毫米每毫升的生物体积可换算为1毫克每升的生物量浓度。采样频率：每年6次；采样点位数量：7个。