The effect of planting grass filter strips on fishes in agricultural headwater streams

Authors: Smiley, Peter - Rocky

Submitted to: Aquatic Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2024
Publication Date: 4/1/2024
Citation: Smiley, P.C. 2024. The effect of planting grass filter strips on fishes in agricultural headwater streams. Aquatic Conservation. Article 34:e4137. https://doi.org/10.1002/aqc.4137.
DOI: https://doi.org/10.1002/aqc.4137

Interpretive Summary: The diversity and abundance of stream fishes in the Midwestern United States has been negatively impacted by agriculture. Conservation practices, such as grass filter strips, are intended to improve stream water quality and provide wildlife habitat are promoted by state and federal stakeholders and voluntarily implemented by producers and landowners. Grass filter strips are a widely used in the United States and frequently planted adjacent to agricultural streams. However, only a limited amount of information is available on the effects of grass filter strips and other conservation practices on stream fishes and instream habitat conditions and long-term assessments of ecological responses are lacking. I documented the long-term effects of planting grass filter strips adjacent to agricultural headwater streams in central Ohio on fish diversity and abundance as well as stream habitat characteristics (i.e., water depth, flow, bottom substrate, and instream wood amounts). Fish diversity and abundance and stream habitat characteristics did not differ among streams with narrow herbaceous streamside habitats, moderate width herbaceous streamside habitats, and wide forested riparian habitats. The lack of improvements in fish diversity and abundance are attributed to the lack of changes in stream habitat characteristics. My results represent the first long term assessment of the responses of fishes and instream habitat conditions to the planting of grass filter strips. My results suggest that the use of grass filter strips in conjunction with practices that improve physical habitat and water quality will benefit fishes in agricultural headwater streams in the Midwestern United States. Our results will assist state agencies, federal agencies, non-profit groups, and consulting agencies involved with conservation and management of fishes and other stream animals and those involved with managing agricultural watersheds.

Technical Abstract: Grass filter strips (i.e., herbaceous riparian buffers) are a widely used conservation practice in the United States to mitigate the impacts of agriculture on agricultural streams and rivers. Yet, only a limited amount of information is available on the effects of grass filter strips on stream fishes and instream habitat conditions and long term assessments are rare. My objective was to document the long-term effects of planting grass filter strips adjacent to channelized agricultural headwater streams on fish community structure and instream habitat. I sampled fishes, instream habitat, and riparian characteristics from three channelized agricultural headwater streams without grass filter strips, three channelized agricultural headwater streams with grass filter strips, and two unchannelized streams having forested riparian habitats in central Ohio from spring of 2006 to fall of 2015. Fish species richness, abundance, darter species richness, percent darter, sunfish species richness, minnow species richness, and percent headwater species did not differ among riparian habitat types. Darter species richness and percent darters were the only fish response variables that exhibited annual differences. Mean water depth, velocity, wet width, instream habitat diversity, mean dominant grain size, and percent instream wood did not differ among riparian habitat types. Mean water depth, water velocity, wet width, and instream habitat diversity exhibited annual differences, but mean dominant grain size and percent instream wood did not. Additionally, mean riparian width, woody vegetation density, and percent canopy cover of the forested streams was greater than that of the unplanted stream and grass filter strip streams. Riparian characteristics did not differ annually. The lack of fish community responses to planting grass filter strips stems is likely due to the lack changes in hydrologic characteristics, substrate, and instream wood amounts 10 to 12 years post-planting. Our results suggest that grass filter strips should not be implemented alone, but in conjunction with conservation and restoration practices that will improve both physical habitat quality and water quality and subsequently benefit the fish communities.