Research

I am improving our understanding of how wild nature and humans coexist and interact in human-dominated aquatic ecosystems.

I research what agriculture can do about its large negative contribution to water quality. My dissertation focused on the environmental science of artificial aquatic systems, especially ditches. Broadly, I am interested in how water connects and sustains socio-ecological systems.

Iowa agricultural drainage water management

I'm working with Dr. Matthew Helmers's lab at Iowa State University Agricultural & Biosystems Engineering to better understand what controls the water quality of drainage from agricultural fields. The expanse of corn and soybean fields that now comprises most of the U.S. Midwest helps launch cultural eutrophication from its tile drain headwaters, through the Mississippi, to the Gulf of Mexico. Similar problems occur and expand around the world, including where I've worked and lived longest, the Coastal Plain of the U.S. Southeast. Climate change and agricultural intensification make the future of an already sprawling problem perilously uncertain. Our projects, at sites around Iowa, reveal what agricultural management practices actually improve and/or exacerbate export of fertilizer-derived excess nitrogen, by how much, how reliably, for what change in crop yield, and under what conditions, including through changes in more natural factors, like weather and soil properties.

This video provides general information about (mission, history, and impacts of) our Agricultural Drainage and Water Quality Research site (ADW), in Gilmore City, Iowa.

image of poster; click for pdf

Corn yields increased under constant fertilizer without reducing nitrate export

I presented this poster about some of my research at the Agricultural Drainage and Water Quality Research site from the Iowa Water Conference in April 2021. The virtual format means I can now easily share this presentation with you too.

graphical abstract for "Artificial Aquatic Systems"

First paper!

Water published the conceptual review "Artificial Aquatic Systems" in August 2018. In 2019, editors selected the paper for the Special Issue 10th Anniversary of Water, and recognized it with a designation of Editor's Choice.

Dissertation:

Ecological Limitations and Potentials of Artificial Aquatic Systems: There’s a lot more to artificial aquatic systems than scientists currently know, and management can be improved with additional knowledge. Successfully defended, but publications still in progress. This research was conducted with PhD advisor Dr. James Heffernan at the Duke University Nicholas School of the Environment Grainger River Center.

Clifford, C.C. Heffernan, J.B. “Artificial Aquatic Systems.” MDPI. Water 2018, 10(8), 1096; https://doi.org/10.3390/w10081096. Available online.

A variety of waterbodies may count as artificial in different contexts. Artificiality is an insufficient explanation for their ecological condition; instead we should test process-based alternatives such as setting, design, and age. Better knowledge of these drivers could improve management potential over a potentially large expanse of ecosystems, known to sometimes provide ecosystem services and disservices of concern. Policy based on our current perception of these systems may reinforce negative expectations.

Irrigation-style ditches in network with a natural creek fresh from the Sierra Nevada Mountains in small Bishop, California, have statistically undifferentiable benthic macroinvertebrate communities from natural creek communities, given similar substrate and same season. Communities do decline in sensitive taxa (mayflies, stoneflies, and caddisflies) and biodiversity downstream across town, presumably as the influence of urban and agricultural land use increases. Communities in creeks that are close together are more similar than communities in ditches that are close together, suggesting some difference in community assembly.

Across 32 agricultural, forested, and freeway roadside ditch reaches in the North Carolina Coastal Plain, all supported predominantly wetland plants, and had at least some soil carbon and signs of wetness. Plant communities differed across site types, however, in response to landscape variables like development in the vicinity and local variables like apparent mowing (on freeway roadsides). Forested sites were more easterly and swampy. Agricultural sites had greater plant cover, including of taxa of driest and wettest wetland indicator groups.

The U.S. National Lakes Assessment, executed by the USEPA, examined over 1000 lakes in 2007 and again in 2012, about half natural and half artificial reservoirs both times. They found differences in the conditions of these two categories, but they did not explore their underlying data to see why the differences occurred. Our structural equations model suggests that algal blooms form through similar processes in both systems, with statistically significant differences, with manmade lakes being less predictable.

diagram suggesting human influence on ecoystems as more cyclical than linear

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