Link between geomorphology and aquatic biodiversity in headwater agricultural ditches in Ohio. (Aquatic Biology 09:00 AM, Saturday, April 5, 2003 Brewer/Frost Science 109 Dr. Gwynne Stoner Rife-Presiding).

Bouchard, Virginie ; Sablak, Gregg

10:00

Agricultural ditches are designed to maximize drainage through straightening, dredging and clearing of riparian vegetation. As a consequence aquatic habitat is destroyed, streams are disconnected from their floodplains, and flow patterns are altered. However, in absence of maintenance, the geomorphology of ditches changes over time with the establishment of a low bench structure and the development of riparian ecosystems. The objective of our research was to determine the relationship between in-stream and riparian habitat structure and biodiversity (i.e., aquatic macroinvertebrates, amphibians and plants) in headwater agricultural ditches in Northwest Ohio. Our hypothesis was that the reestablishment of floodplain connection and riparian habitats would increase biodiversity in ditches. To test our hypothesis, we sampled macroinvertebrates, amphibian and plant communities in three types of ditch reaches: (1) ditches with riparian ecosystem (e.g., ditches with tree; n = 7), (2) ditches without riparian ecosystems but with a low narrow floodplain bench (e.g., ditches with bench; n=8), and (3) ditches without riparian ecosystems and without floodplain bench (e.g., control ditches; n=7). Macroinvertebrates richness and diversity did not differ significantly among the three types of ditches. However, the ditches with bench had the highest average richness (23.3 species) and a Shannon diversity index of 1.47 while the ditches with trees had the lowest richness (16.8 species) and Shannon diversity index of 1.40. We suspect that ecosystem productivity is lower in ditches with riparian zone, as in-stream autotrophs are much less abundant due to shading by the tree canopy. We have found substrate quality to be positively correlated with macroinvertebrate richness.

VIRGINIE BOUCHARD BOUCHARD.8@OSU.EDU AND GREGG SABLAK, OHIO STATE UNIVERSITY, SCHOOL OF NATURAL RESOURCES, 2021 COFFEY RD, COLUMBUS OH 432.10