Anatoxin concentrations, algal assemblages, and water quality data for the South Fork Eel, Salmon, and Russian Rivers in northern California, 2022-2023

We collected this data to better understand the timing of peak benthic cyanobacterial mat occurrence (specifically taxa associated with anatoxin production, Microcoleus and Anabaena) and mat anatoxin concentrations in rivers. We sampled in northern California on the South Fork Eel, Salmon, and Russian Rivers biweekly in 2022, and the Salmon River biweekly and South Fork Eel weekly in 2023. During each sampling event, we conducted benthic cover surveys, measured in-situ water quality parameters (temperature, pH, dissolved oxygen, conductivity), and collected surface water samples and targeted cyanobacteria samples. In 2022 on all rivers and in 2023 at the Salmon River, we also collected distributed non-targeted periphyton samples to characterize full-reach community compositions. All sampling was completed in 150-m reaches upstream of sensors recording continuous dissolved oxygen, conductivity, and temperature data. We analyzed surface water samples for nitrate, ammonium, soluble reactive phosphate, total dissolved carbon, and dissolved organic carbon. We also analyzed surface water samples from 2022 for major anions (Cl, SO4, Br) and cations (Na, K, Mg, Ca). Targeted-cyanobacteria and non-target periphyton samples were analyzed for anatoxins (and two other classes of toxins, microcystins and cylindrospermopsins), relative abundance of algal taxa (via microscopy), ash-free dry mass, and chlorophyll-a. To estimate mean river depth within the dissolved oxygen footprint upstream of sensors, we kayaked portions of the river and collected river depth measurements. We also measured discharge at each river excluding the Salmon River (due to high discharge) and completed pebble counts at the South Fork Eel River to obtain sediment grain size distributions. Lastly, we estimated daily reach-scale river metabolism (gross primary productivity and ecosystem respiration) using data from dissolved oxygen sensors with the "streamMetabolizer" package in R at all sensor placements.本数据集旨在深入解析河流中底栖蓝藻垫（benthic cyanobacterial mat）峰值出现的时间，具体聚焦于与鱼腥藻毒素（anatoxin）合成相关的类群：鞘丝藻属（Microcoleus）与鱼腥藻属（Anabaena），同时测定蓝藻垫的鱼腥藻毒素浓度。2022年，我们在加利福尼亚北部的南福克伊尔河、萨蒙河与俄罗斯河开展每两周一次的采样；2023年，对萨蒙河维持每两周一次的采样频率，对南福克伊尔河调整为每周一次采样。每次采样期间，我们开展底栖覆盖度调查，测定原位水质参数（in-situ water quality parameters：水温、pH值、溶解氧（dissolved oxygen）、电导率（conductivity）），并采集地表水样本（surface water samples）与靶向蓝藻样本（targeted cyanobacteria samples）。2022年所有调研河流，以及2023年的萨蒙河，我们还采集了分布式非靶向周丛生物（periphyton）样本，以表征全河段的群落组成（full-reach community compositions）。所有采样点位均设置在记录连续溶解氧、电导率与水温数据的传感器（sensors）上游150米河段（150-m reaches）内。我们对地表水样本开展了硝酸盐（nitrate）、铵态氮（ammonium）、可溶性活性磷（soluble reactive phosphate）、总溶解碳（total dissolved carbon）与溶解有机碳（dissolved organic carbon）的检测分析；2022年的地表水样本还额外检测了主要阴离子（major anions：Cl⁻、SO₄²⁻、Br⁻）与阳离子（cations：Na⁺、K⁺、Mg²⁺、Ca²⁺）。靶向蓝藻样本与非靶向周丛生物样本被用于检测鱼腥藻毒素（anatoxin）以及另外两类毒素：微囊藻毒素（microcystins）与柱孢藻毒素（cylindrospermopsin），同时通过显微镜镜检（microscopy）测定藻类分类群相对丰度，测定灰分干重（ash-free dry mass）与叶绿素a（chlorophyll-a）含量。为估算传感器上游溶解氧影响范围（dissolved oxygen footprint）内的平均河深，我们使用皮划艇勘察了部分河段并开展河深测量（river depth measurements）。我们还测定了除萨蒙河外所有调研河流的径流量（discharge，因萨蒙河径流量过高未开展此项测定），并在南福克伊尔河开展砾石计数（pebble counts）以获取沉积物粒径分布（sediment grain size distributions）数据。最后，我们依托R语言的"streamMetabolizer"包（"streamMetabolizer" package in R），利用所有传感器点位的溶解氧监测数据，估算得到日尺度的河段河流代谢参数：总初级生产力（gross primary productivity）与生态系统呼吸（ecosystem respiration）速率。