Agricultural conservation practices and aquatic ecological responses

Authors: Lizotte, Richard; Smiley, Peter - Rocky; GILLESPIE, ROBERT - Indiana University-Purdue University; Knight, Scott

Submitted to: Agriculture Ecosystems and the Environment
Publication Type: Review Article
Publication Acceptance Date: 6/15/2021
Publication Date: 6/18/2021
Citation: Lizotte Jr, R.E., Smiley, P.C., Gillespie, R.B., Knight, S.S. 2021. Agricultural conservation practices and aquatic ecological responses: a synthesis of perspectives across ecosystem types and watersheds. Agriculture Ecosystems and the Environment. 13(12). Article 1687. https://doi.org/10.3390/w13121687.
DOI: https://doi.org/10.3390/w13121687

Interpretive Summary: Because there are gaps in our understanding of how conservation practices affect aquatic ecology at the watershed level, there is a need to summarize and synthesize what is currently known. The Conservation Effects Assessment Project Watershed Assessment Study (CEAP) was used to examine how conservation practices in three watersheds affected a variety of ecological responses. CEAP studies found that conservation practices in Midwest streams that only improve water quality don't affect fish communities. Studies in a southeastern CEAP lake showed that conservation practices that decreased suspended sediment led to increases in summer algae. Synthesis of CEAP ecology studies highlight the importance of conservation practices in improving and enhancing environmental quality at the watershed level. Our results are of interest to regulatory and other agencies and researchers by providing additional information to improve and sustain river, stream and lake ecology and overall environmental quality using a variety of conservation practices at the watershed level.

Technical Abstract: Conservation agriculture practices (CAs) have been internationally promoted and used for decades to enhance soil health and mitigate soil loss. An additional benefit of CAs has been mitigation of agricultural runoff impacts on aquatic ecosystems. Countries across the globe have agricultural agencies that provide programs for farmers to implement a variety of CAs. Increasingly there is a need to demonstrate that CAs can provide ecological improvements in aquatic ecosystems. Growing global concerns of lost habitat, biodiversity, and ecosystem services, increased eutrophication and associated harmful algal blooms are expected to intensify with increasing global populations and changing climate. We conducted a literature review identifying 88 studies linking CAs to aquatic ecological responses since 2000. Most studies were conducted in North America (78%), primarily the United States (73%), within the framework of the USDA Conservation Effects Assessment Project. Identified studies most frequently documented macroinvertebrate (31%), fish (28%), and algal (20%) responses to riparian (29%), wetland (18%), or combinations (32%) of CAs and/or responses to eutrophication (27%) and pesticide contamination (23%). Notable research gaps include better understanding of biogeochemistry with CAs, quantitative links between varying CAs and ecological responses, and linkages of CAs with aquatic ecosystem structure and function.