Benthic Macro Fauna Colonization on Inudated Floodplain Sites Along the Lower Missouri River

Miller, Marcus

Since the completion of the Missouri River Bank Stabilization and Navigation Project and the regulation of river discharge, floodplain inundation cycles have become infrequent. The absence of this natural process may be contributing to the decline of native fauna.

Benthic macro fauna play an important function in the river ecosystem. Because of their abundance and position in the aquatic food chain, they play a critical role in the cycling of nutrients and energy. They are a major source of food for many Missouri River fish species during a portion of/or all of their life history, including the federally endangered pallid sturgeon.

The 2011 high water event presented a unique opportunity to assess organismal response to seasonal inundation. A portion of the data collected during this prolonged high water event allowed us to assess how floodplain habitats function in relation to benthic macro fauna colonization and retention.

Four locations were sampled Dalbey Bottoms, South Dalbey Bottoms, Baltimore Bottoms, and Overton Bottoms . 10 benthic samples were taken using a Petite Ponar grab sampler. Abundance was calculated as Individuals/m². Non-metric multidimensional scaling (MDS) showed a 65% similarity between trips 1 and 2 at Baltimore, and all trips to South Dalbey. Analysis of similarity (ANOSIM), (R= 0.42, p=0.001) showed no differences between Dalbey trips 4,5, and 6 (R < 0.2), and between all of the South Dalbey trips (R < 0.07). Differences were seen between Baltimore trip 1 and trips 5 and 6 (R > 0.8), Baltimore trip 2 and 6(R = 0.83), and Dalbey 1 and 6 (R = 0.92). Species diversity peaked at around 3 weeks post inundation at 2 of the 3 initial sites, Dalbey, and Baltimore Bottoms. The highest species diversity was recorded at Baltimore Bottoms on July 19^th.

Being able to study and analyze a diversity of habitats and assessing how they function greatly increases our knowledge when creating the best SWH restoration projects. Building habitats that allow for seasonal short term inundation could increase invertebrate abundance and diversity within the Missouri River. This may benefit many native large river fish species including the endangered pallid sturgeon.