Change in age structure over an annual cycle for riffle beetles found in submerged rootmats in the Whitewater River, Missouri

 

Changes in population dynamics over time for various species of riffle beetles are poorly understood, especially as they occur in submerged rootmats.  In order to assess these changes in terms of age structure, several genera of Elmidae (Ancyronyx, Macronychus, and Microcylloepus) were sampled over an annual cycle from submerged rootmats within the Whitewater River, Bollinger County, Missouri.  Every other month, from July 2011 to May 2012, twelve samples were gathered from three locations along the river.  The samples were sorted and riffle beetles were identified to the lowest taxonomic level.  Abundance values of both larvae and adults were recorded for each species. Age classes were developed from head capsule measurements of Ancyronyx, Macronychus, and Microcylloepus larvae.  Results and associated statistical analyses are pending, but will be reported in this poster presentation.