Long term limnological measurements in Acton Lake, a southwest Ohio reservoir, and its inflow streams: 1992-2023

Long-term data were collected from Acton Lake and its inflow streams on a suite of physical, chemical and biological variables. The data are collected as part of long-term research investigating how Acton Lake, a eutrophic reservoir, responds to changes in ecosystem subsidies of detritus (sediments) and nutrients. Our data span 31 years, from 1992-2023, although for some parameters the data set spans a shorter time frame within this period. In three of Acton Lake’s inflow streams, collectively constituting ~86% of the lake’s watershed, we include data on hourly stream discharge, as well as concentrations of suspended sediments, ammonium-N, nitrate+nitrite-N, and soluble reactive phosphorus (P). Data on the concentrations of these constituents were collected at various time scales depending on stream discharge (usually every 6-8 hours during storms, every 1-3 days during baseflow). In Acton Lake, we collected data on several parameters from an “outflow” site, at the deepest part of the lake where the water column is usually thermally stratified in summer. Vertical profile data were collected for temperature, dissolved oxygen, photosynthetically active radiation (PAR), and chlorophyll. Depth profile data were collected at 0.5 or 1 m intervals (depending on depth and year), usually weekly from April or May until September or October. In addition, data for several parameters were obtained from “integrated samples” that collect water from the lake surface to the bottom of the euphotic zone (defined as the depth at which PAR equals 1% of surface PAR) with a tube or pump. Parameters for which integrated data are presented include chlorophyll; suspended solids; non-volatile suspended solids; particulate (seston) carbon, nitrogen and phosphorus; and total nitrogen and total phosphorus. We also collected Secchi depth data, using standard methods. Larval fish were collected in the top 1-3 meter stratum of the water column with a metered net to generate estimates of lake-wide larval fish density. Finally, zooplankton were collected by towing a net vertically through the water column; we present data on biomass and abundance of major zooplankton groups here. Several of these parameters are also reported for our “inflow” site. This site is in the shallow part of the lake, near the locations where inflowing streams enter the reservoir. Conditions at this site are considerably more variable than the “outflow” site. The “inflow” is relatively shallow (0.75-1.5m, depending on lake level), does not thermally stratify, and is typically more turbid than the “outflow” site, although water clarity and color varies greatly with storm influences. Larval fish were collected in the top 1-3 meter stratum of the water column with a metered net to generate estimates of lake-wide larval fish density. Finally, zooplankton were collected by towing a net vertically through the water column; we present data on biomass and abundance of major zooplankton groups here.

本数据集采集自阿克顿湖（Acton Lake）及其入流溪流，涵盖了长达31年的物理、化学与生物变量观测数据。本数据集作为长期研究的一部分，旨在探究富营养化水库阿克顿湖如何响应碎屑（沉积物）与养分的生态系统输入变化。数据的时间跨度为1992年至2023年，但部分参数的观测周期仅覆盖该时段内的部分区间。在构成该湖流域约86%的3条入流溪流中，我们采集了逐小时的溪流流量数据，以及悬浮沉积物、铵态氮（ammonium-N）、硝态氮+亚硝态氮（nitrate+nitrite-N）与可溶性活性磷（P）的浓度数据。上述组分的浓度采样频率随溪流流量动态调整：暴雨期间通常每6-8小时采样一次，基流期则每1-3天采样一次。在阿克顿湖内，我们在夏季通常出现热分层的湖体最深处设置出水位点（outflow site），并在此采集多项参数数据：包括温度、溶解氧、光合有效辐射（PAR）与叶绿素的垂直剖面数据，采样间隔为0.5或1米（依湖深与年份而定），采样周期通常为每周一次，从4月或5月持续至9月或10月。此外，我们还通过管具或抽水装置采集整合水样（integrated samples），即从湖表至真光层底部（光合有效辐射强度为表层1%的深度）的混合水样，该类水样涵盖的参数包括：叶绿素、悬浮颗粒物、非挥发性悬浮颗粒物、颗粒（悬浮有机质）碳、氮与磷，以及总氮与总磷。我们同时采用标准方法采集了塞氏盘透明度（Secchi depth）数据。我们使用带计量装置的网具在水体上层1-3米层采集幼鱼样本，以估算全湖范围的幼鱼种群密度；并通过垂直拖网采集浮游动物，本数据集包含主要浮游动物类群的生物量与丰度数据。部分参数的观测数据同时来自入流位点（inflow site），该位点位于湖体浅水区，临近溪流汇入水库的位置。该位点的环境条件相较出水位点波动更为剧烈：其水深较浅（0.75-1.5米，依湖水位而定），无热分层现象，且通常较出水位点更为浑浊；不过水体透明度与色度会随暴雨事件发生显著变化。我们同样在此入流位点采集了幼鱼与浮游动物样本，相关数据亦包含于本数据集内。