COMPARING SPECIES RICHNESS AND TAXONOMIC DIVERSITY OF AQUATIC INVERTEBRATES IN RESTORED AND NATURALIZED AGRICULTURAL DITCHES
In the Midwest, agricultural ditches are designed to efficiently move excess water, nutrient and sediment away from fields to prevent flooding and enhance agricultural productivity. Conventional ditches are maintained through dredging, which reduces habitat quality and ultimately limits biodiversity and abundance of freshwater invertebrates dependent on benthic habitat. Unmaintained ditches often experience bank failure, which leads to natural floodplains and meanders, possibly resulting in improved ecological conditions. Alternatively, the two-stage ditch jumpstarts naturalization by constructing inset floodplains that promote nutrient and sediment retention during high flows. To test the effect of naturalization and floodplain restoration on biological integrity, we quantified the abundance and richness of macroinvertebrates using multiple Hess samples from contrasting sites in the Shatto Ditch Watershed (Kosciusko Co., IN) during Summer 2017. Both insect abundance and richness were significantly higher in the naturalized reach, which coincided with improved stream substrate (i.e., higher proportion of pebble and gravel) compared to the two-stage ditch. Overall, allowing streams to naturalize may be more useful for restoring biological integrity, while two-stage ditches may optimize nutrient and sediment retention.
Matt T. Trentman (Co-Presenter/Co-Author), University of Notre Dame, email@example.com;
Edward Lopez (Co-Presenter/Co-Author), University of Notre Dame, firstname.lastname@example.org;
Jennifer L. Tank (Co-Presenter/Co-Author), University of Notre Dame, email@example.com;
Anna-Sophie Hoppe (Primary Presenter/Author), Eckerd College, firstname.lastname@example.org;