DOI: 10.5061/dryad.pk0p2ngk6
title: Zooplankton and water quality data for 37 lakes in the Gwich'in and Inuvialuit regions of the Northwest Territories

description: This dataset includes zooplankton and water quality data from 37 lakes
 sampled in the Northwest Territories, Canada, from the Dempster and
 Inuvik-Tuktoyaktuk Highways during July and August of 2017 and 2018. It
 was collected as part of a project to determine how physicochemical
 variables affect zooplankton and fish communities in small Arctic lakes.
description: Our study includes 37 lakes located along the Dempster and
 Inuvik-Tuktoyaktuk Highways in the Northwest Territories. Lakes along the
 Dempster Highway were sampled between August 17<sup>th</sup>
 and September 1<sup>st</sup>, 2017 while lakes along the
 Inuvik-Tuktoyaktuk Highway were sampled between August
 6<sup>st</sup> and August 27<sup>th</sup>,
 2018. We collected data on surface area and maximum
 depth for each lake by constructing bathymetric maps using a Humminbird
 Helix 5 chartplotter (Johnson Outdoors Marine Electronics, Inc), in
 combination with Reefmaster bathymetry software (Reefmaster Ltd.). We also
 collected water quality data including Secchi depth (water clarity),
 turbidity, conductivity, dissolved oxygen (DO), pH, total nitrogen (TN),
 total phosphorus (TP), total organic carbon (TOC), calcium,
 chlorophyll-<i>a</i>,<i> </i>and water temperature
 (Table 1). To obtain water clarity measurements, we lowered a Secchi disk
 over the shady side of the boat at the deepest point on the lake. At the
 same location, we measured turbidity, conductivity, DO, pH, and
 temperature, using a Manta+ multiparameter probe (Eureka Water Probes) at
 a depth of 1 m. We also collected water for the measurement of TOC and
 calcium levels at the same site using a 3 m polyethylene integrated tube
 sampler. We used a Perkin Elmer Optima 8000 Inductively Coupled Plasma
 Optical Emission Spectroscopy (ICP-OES) instrument to measure calcium
 concentrations, and a Shimadzu TOC-LCPH Carbon and Nitrogen analyzer
 (Shimadzu Corp.) to measure TN and TOC. We collected surface water samples
 from the shoreline of each lake for chlorophyll-<i>a </i>and
 TP measurements. To measure TP, we digested samples in an autoclave with
 ammonium persulfate and sulfuric acid following EPA method 365.1. We then
 used SEAL method G-103-93 to measure TP colorimetrically using the SEAL
 Continuous Segmented Flow Analyzer (SEAL Analytical, Inc.). To measure
 chlorophyll-<i>a </i>levels we filtered 250 mL water samples
 through Fisherbrand G4 glass fiber filters, extracted
 chlorophyll­-<i>a</i> from the filters using methanol, and
 analyzed the quantity of chlorophyll using a Turner TD700
 fluorometer. We collected zooplankton samples from each
 lake at the point of maximum depth and preserved them on site using 95%
 ethanol. For lakes greater than 3 m in depth, we collected a single
 vertical haul using a 35-cm diameter, 50 μm mesh size zooplankton net. For
 shallow lakes less than 3 m in depth, where a vertical tow was not
 possible, we collected zooplankton by towing the net behind the boat for
 approximately 60 seconds. In both cases, we used a mechanical flowmeter
 attached to the mouth of the net to determine the volume of water that
 passed through the net. In the laboratory, we identified crustacean
 zooplankton to the species level according to Haney et al. (2013) using a
 magnification of 40x to 400x depending on the size of the
 species. We identified rotifers to the genus level using the
 same classification key by examining samples in a Sedgewick Rafter
 counting slide at 40-400x magnification. Haney, J.F.,
 Aliberti, M.A., Allan, E., Allard, S., Bauer, D.J., Beagen, W., Bradt,
 S.R., Carlson, B., Carlson, S.C., Doan, U.M., Dufresne, J., Godkin, W.T.,
 Greene, S., Kaplan, A., Maroni, E., Melillo, S., Murby, A.L., Smith, J.L.,
 Ortman, B., Quist, J.E., Reed, S., Rowin, T., Schmuck, M., Stemberger,
 R.S., and Travers, B. 2013. An image-based key to the zooplankton of North
 America, version 5.0. Available from
 http://cfb.unh.edu/cfbkey/html/.