Life Sciences Commons^™

Macrophytes And Atrazine In Ponds Of Southwest Missouri, Christine Michelle Cornish

MSU Graduate Theses

Wetlands are often the ultimate destination of agrochemicals. The increased use of these pollutants has resulted in their increased transport, via runoff and spray drift, into wetlands. Atrazine, a commonly used herbicide, has been detected in surface water, groundwater, soil, and sediment, and has shown to have adverse impacts on aquatic biota, such as fish and amphibians. Few studies have reported on the relationships between atrazine and macrophytes. I measured atrazine concentrations in surface sediments in agricultural, conservation, and golf course ponds of southwest Missouri, and investigated how those concentrations might be related to macrophyte communities, and pond environmental characteristics. …

The Combined Effects Of Atrazine And Tetracycline On Primary Producers And Zooplankton In Freshwater Microcosms, Madison R. Kelly

Honors College Theses

Widespread use of agrochemicals such as herbicides and antibiotics increases their likelihood of entering aquatic systems in mixture. Despite different modes of action, atrazine (herbicide) and tetracycline (antibiotic) adversely affect non-target photosynthetic organisms, such algae and macrophytes, with the potential to reduce food availability to higher trophic levels. However, the effects of simultaneous exposure to both contaminants have yet to be determined. I hypothesized that a mixture of atrazine and tetracycline affects freshwater communities differently than each compound alone. A microcosm experiment was conducted to test effects of environmentally relevant concentrations of atrazine (1 μg L^-1) and tetracycline …

Do Host‐Associated Gut Microbiota Mediate The Effect Of An Herbicide On Disease Risk In Frogs?, Sarah A. Knutie, Caitlin R. Gabor, Kevin D. Kohl, Jason R. Rohr

Integrative Biology Faculty and Staff Publications

1. Environmental stressors, such as pollutants, can increase disease risk in wildlife. For example, the herbicide atrazine affects host defences (e.g. resistance and tolerance) of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), but the mechanisms for these associations are not entirely clear. Given that pollutants can alter the gut microbiota of hosts, which in turn can affect their health and immune systems, one potential mechanism by which pollutants could increase infection risk is by influencing host‐associated microbiota.
2. Here, we test whether early‐life exposure to the estimated environmental concentration (EEC; 200 μg/L) of atrazine affects the gut bacterial composition of …

The Tensile Root Strength Of Emergent Coastal Macrophytes, Lauris Olivia Hollis

LSU Doctoral Dissertations

Spartina patens is a dominant emergent macrophyte in fresh, intermediate, and brackish marshes along the Atlantic and Gulf coasts of United States where its biomechanical properties are a key component of wetland health and resilience. Its root biomass and tensile root strength are essential for anchorage, erosion protection, and are important determinants of soil strength. Nutrients and the herbicide atrazine are suspected of negatively impacting this wetland plant and others. The objectives of this study were to: 1) ascertain the tensile root strength of five emergent coastal macrophytes in coastal estuaries, and 2) test the effects of nutrient addition, atrazine …

Integrating Half Rates Of Dicamba And Atrazine With Increasing Sorghum Density And Nitrogen Rate For Palmer Amaranth Control, I. B. Cuvaca, A. J. Foster, R. Currie

Kansas Agricultural Experiment Station Research Reports

Sorghum is an important crop in Kansas. However, in-season weed control options for sorghum are limited. This limitation is exacerbated by Palmer amaranth season-long interference and resistance to multiple herbicide modes of action.

This 2-year study investigated the ability of a contrasting combination of cultural and chemical practices to control Palmer amaranth while maintaining or improving sorghum grain yield. Particular research emphasis was to evaluate the effect(s) of integrating half rates of dicamba and atrazine applied as PRE with increasing sorghum density and nitrogen rate on Palmer amaranth control and grain yield in an irrigated environment.