Lake water quality, chemistry and zooplankton composition for 16 lakes surrounding the Green Lakes Valley, 2016

This dataset contains water chemistry measurements made from 16 different lakes north and south of LTER site in the green lakes valley. At each visit water samples were collected for analysis of chlorophyll a and nutrient analysis and field measurements were recorded for pH, temperature, specific conductivity, dissolved oxygen (DO), % saturation, secchi depth, PAR. Secchi depth was measured using a 30cm disk to the nearest 0.25 meter and here recorded at the 0m row in the data file however it is a measurement of depth and so the units are meters. Most samples were collected between 0900 and 1300 MST. The first sampling date occurred shortly after lake had become ice free and then if the lake was at least 3 meters deep it was re-surveyed at approximately 2 week intervals. All data are collected from an inflatable raft at the point of deepest depth. All water samples were taken at the surface (0m), and the hypolimnion (about 2m above the lake sediment) using a Van Dorne sampler. Chlorophyll-a was extracted from water sample filters and absorbance was measured before and after acidification to quantify chlorophyll a concentration. Field measurements were conducted using a YSI either DO or multiple probe meter (YSI MPS 556) and a Li-Cor meter with a quantum sensor. Zooplankton samples were collected opportunistically 3 times throughout the summer, once immediately after ice-out and two more times with at least 14 days bewteen each subsequent visit. Zooplankton were sampled at the deepest location of each lake by pulling a conical net (Wisconsin net) vertically through the water column (i.e., vertical tow sample). The Wisconsin net is 0.9m long with an opening of an inner diameter of 0.2m and a mesh size of 80um. The vertical tow samples are taken from approximately 0.5 m off the lake bottom. After the net is raised and the sides rinsed, the sample is transferred to a 250 mL jar and preserved in a solution of 80% Ethanol. Jars are labeled with date (yyyy-mm-dd), time hh:mm (MST), lake, depth and net details and stored at room temperature until analysis.