Abundance and morphometry of Daphnia lumholtzi in Lake Texoma, OK, USA in 2010-2011

Samples were collected at five pelagic sites (see below for coordinates) over the course of fourteen months (June 2010-July 2011). Zooplankton were collected using vertical tow over the full water column (depth-integrated) with a Wisconsin-type net (350-μm mesh, aperture diameter 10.5 cm).

Zooplankton were enumerated and morphology of Daphnia lumholtzi was measured using a dissecting microscope. Water quality parameters, including water temperature (°C), salinity (practical salinity units, PSU), dissolved oxygen (mg L−1), chlorophyll (μg L−1), phycocyanin (proportional to μg L−1), total nitrogen (μM), total phosphorous (μM), native Daphnia spp. density (females L−1) and Secchi depth (m). Water samples for nutrients (nitrogen and phosphorus) were taken as depth integrated samples over the upper 10 m.