Cornish CM, Martin AP, Hamersky M, Frazier CF, Kastens J, Harris TD (2026) From sink to source: The start of oxic internal phosphorus loading in Marion Reservoir, Kansas. Lake and Reservoir Management (in revision)
Cornish CM, Otte M, Sweetman JN (2026) Sediment microbial communities in long-term wetland restorations within the Prairie Pothole Region of the United States. Restoration Ecology, e70306. https://doi.org/10.1111/rec.70306
Cornish CM, Johnson OF, Bansal S, Meier J, Harris TD, Sweetman JN (2024) Common use herbicides increase wetland greenhouse gas emissions. Science of the Total Environment, 933:172881. https://doi.org/10.1016/j.scitotenv.2024.172881
Cornish CM and Sweetman JN (2023) A perspective on how glyphosate and 2,4-D in wetlands may impact climate change. Frontiers in Environmental Science, 11:1282821. https://doi.org/10.3389/fenvs.2023.1282821
Cornish CM, Bergholz P, Schmidt K, Sweetman J (2023) How benthic sediment microbial communities respond to glyphosate and its metabolite: A microcosm experiment. Microbial Ecology. https://doi.org/10.1007/s00248-023-02296-6
My work at the Kansas Biological Survey is extremely diverse and consists of long term water quality monitoring, paleolimnology, stream surveys, and experimental limnological research.
Mussel grubbing
High frequency buoy
Greenhouse gas chambers
Sediment core subsampling
Microplastics Affect Biogeochemical Cycling
Benthic microbial communities are the primary drivers of nitrification and methanogenesis, which are crucial biogeochemical processes for the cycling of nitrogen and carbon, respectively. Microplastics, which are ubiquitous in aquatic ecosystems, are potentially altering biogeochemical cycles, which could have larger implications by unbalancing nutrient cycling. However, the effects of microplastics on specific biogeochemical processes are not well understood. We used incubations to investigate the effects of polyvinylchloride and polyester fibers on oxic and anoxic processes. PES microplastics were found to potentially stimulate denitrification and aerobic respiration, whereas PVC may inhibit methanogenesis. Overall, these results suggest that microplastics could affect biogeochemical cycling, but may differ with environmental factors across ecosystems.
*research conducted at Virginia Tech
Microbial Responses to Common Herbicide
Glyphosate is the most commonly used agricultural herbicide in the world and it is a frequent contaminant of aquatic ecosystems. Due to its chemical properties it often binds to benthic sediments or is metabolized by microorganisms, where it can have both advantageous and disadvantageous effects on benthic microbial communities depending on environmental factors, exposure history, dose, etc. To investigate the impacts of glyphosate and its main metabolite AMPA (aminomethlyphosphonic acid) on benthic sediment microbial communities collected from the Prairie Pothole Region (PPR); and to compare the impacts of analytical grade glyphosate and AMPA to a commercially available glyphosate-based formula. There were no differences among any treatments in species richness, diversity, or composition two weeks after a single herbicide treatment. Surprisingly, even the high treatment didn't have differences, which was ~40x greater than residues detected in wetlands. This suggests that microbial species in the PPR may be expressing tolerance to glyphosate.
Funding: North Dakota EPSCoR Seed Grant
Herbicides and Greenhouse Gases
Global herbicide use has been increasing since the rapid adoption of herbicide-resistant crops in the 1990's and the rise in population. Many weed species have developed tolerance to glyphosate, in particular, which is a globally used herbicide. As a result glyphosate is being used in "pesticide cocktail" mixtures with 2,4-D, another common herbicide, to combat tolerant target species. Subsequently, wetlands are subjected to chemical stressors, which could influence biogeochemical cycling, thus greenhouse gas emissions. We tested the individual and mixed effects of glyphosate and 2,4-D on greenhouse gas dynamics in microcosms. There were no treatment effects on nitrous oxide, however carbon dioxide was significantly impacted by high glyphosate concentrations. Methane was not significantly impacted by treatment, but there were increased patterns of potential synergistic effects of mixed treatments. This study suggests that extensive use of herbicides may disrupt biogeochemical processes, in particular carbon cycling.
Collaboration: USGS Northern Prairie Wildlife Research Center
Hydrologic Restoration of Prairie Pothole Wetlands
Wetland degradation in the Prairie Pothole Region (PPR) is substantial, where >50% have been altered or lost due to agricultural development and other human activities. However, restoration efforts to conserve crucial ecosystem services have occurred for several decades. Microorganisms serve as the foundation for many ecosystem services such as pollutant degradation and biogeochemical cycling, but these processes may be impacted by restoration disturbance to sediments. We compared benthic sediment microbial communities in restored and natural wetlands to investigate the potential long-term effects of restoration. There were no differences between natural and restored wetland microbial community richness or diversity, suggesting that hydrologic restoration of wetlands in the North Dakota PPR may be ecologically beneficial whilst still not impacting microbial communities long term.
Funding: EPA Region 8 Wetland Program Development Grant