Comparisons of Phytoplankton and Zooplankton Communities in Lower Missouri River Mainstem and Floodplain Sites in 2011

In 2011, portions of the Lower Missouri River experienced high water conditions resulting in the inundation of significant portions of the floodplain.  This necessitated the US Army Corps of Engineers, and partners, to modify annual sampling programs that support the Missouri River Recovery Program.  Sampling efforts were shifted from main channel locations to inundated public sites on the floodplain.  Data were collected to assess the chemical and biological responses to high water.  Our efforts focused on the differences in water quality, phytoplankton, and zooplankton communities between mainstem and floodplain sites.  Data were also compared to samples collected from mainstem and created shallow water habitat sites (e.g., backwaters and chutes) in 2010 for broader comparisons with non-flood years.  As expected, the water quality and plankton communities differed both between floodplain and mainstem sites in 2011 and between flood and non-flood years.  We were particularly interested in assessing how zooplankton varied in response to floodplain inundation because most riverine fish utilize zooplankton during part of their life cycle.  Therefore, our presentation will focus on the factors that control the diversity, distribution, and abundance of zooplankton and provide an assessment of the potential benefit that zooplankton provide to native fishes in these habitats.