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.

本数据集的采集旨在系统解析河流中底栖蓝藻垫（benthic cyanobacterial mat）发生峰值的时间节点，以及与鱼腥藻毒素（anatoxin）合成相关的类群（微鞘藻属*Microcoleus*与鱼腥藻属*Anabaena*）对应的藻垫鱼腥藻毒素含量。2022年，研究团队在加利福尼亚州北部的南福克艾尔河（South Fork Eel River）、萨蒙河（Salmon River）与俄罗斯河（Russian River）开展双周采样；2023年则维持对萨蒙河的双周采样频率，将南福克艾尔河的采样频次调整为周度采样。每次采样期间，研究团队均开展底栖覆盖度调查，原位测定水温、pH值、溶解氧、电导率等水质参数，并采集地表水样品与靶向蓝藻样品。2022年对所有目标河流、2023年对萨蒙河，研究团队额外采集了分布式非靶向周丛生物（periphyton）样品，以表征完整河段的群落组成结构。所有采样点位均设置在连续记录溶解氧、电导率与温度数据的传感器上游150米河段范围内。研究团队对采集的地表水样品开展了硝酸盐、铵盐、可溶性反应性磷（soluble reactive phosphate）、总溶解碳（total dissolved carbon）与溶解有机碳（dissolved organic carbon）的检测分析；此外还对2022年采集的地表水样品开展了主要阴离子（anion）与阳离子（cation）的检测，涵盖氯离子（Cl⁻）、硫酸根（SO₄²⁻）、溴离子（Br⁻）以及钠离子（Na⁺）、钾离子（K⁺）、镁离子（Mg²⁺）、钙离子（Ca²⁺）。针对靶向蓝藻样品与非靶向周丛生物样品，本研究检测了鱼腥藻毒素（anatoxin）以及另外两类毒素：微囊藻毒素（microcystins）与柱孢藻毒素（cylindrospermopsins）；同时通过显微镜镜检分析藻类类群的相对丰度，并测定了灰分干重与叶绿素a（chlorophyll-a）含量。为估算传感器上游溶解氧监测覆盖河段内的平均河深，研究人员划皮划艇遍历部分河段并采集河深数据。此外，研究团队对除萨蒙河外的所有目标河流开展了流量测定（因萨蒙河流量过高无法开展该操作），并在南福克艾尔河完成砾石计数以获取沉积物粒径分布数据。最后，本研究利用所有传感器点位的溶解氧监测数据，结合R语言的"streamMetabolizer"包，估算了河段尺度的每日河流代谢参数，包括总初级生产力（gross primary productivity）与生态系统呼吸（ecosystem respiration）速率。