The Tensile Root Strength of Spartina patens: Response to Atrazine Exposure and Nutrient Addition

Lauris O Hollis,R Eugene Turner

doi:10.1007/s13157-019-01126-1

Abstract

Coastal wetlands are receiving basins for inland runoff that contains numerous compounds such as nutrients and herbicides, which may have negative effects on wetland plants. Spartina patens is a dominant emergent macrophyte in low salinity wetlands whose biomechanical properties contribute to wetland stability against erosive forces and herbivore grazing. We conducted two greenhouse experiments with six levels of nutrients and three levels of atrazine doses to test the hypothesis that exposure to nutrients and atrazine changes the tensile root strength of S. patens. The results revealed that the tensile root strength of S. patens was not affected by either atrazine exposure or nutrient addition after 60 days, whereas the plants treated with atrazine, nutrient addition, or an atrazine-nutrient combination had significantly less tensile root strength than the Control after 212 days. There were no significant differences in tensile root strength between the main effects and treatment combinations, and hence, no interactive effects of nutrient addition and atrazine exposure. These results suggest that the influx of poor quality water into coastal wetlands will decrease the tensile root strength of S. patens and make coastal wetlands even more vulnerable to sea level rise and climate change.

Highlights

Wetlands may be receiving basins for surface and subsurface flow because of their hydrogeomorphic position in the landscape
The tensile root strength of S. patens in these experiments declined with exposure to atrazine, nutrients, and in combination with both
The phosphorus and the nitrogen-phosphorus combination had the greatest effect on tensile root strength compared to the other treatments

Summary

Introduction

Wetlands may be receiving basins for surface and subsurface flow because of their hydrogeomorphic position in the landscape. In particular, bring nutrients and herbicides into wetlands as a consequence of land use and the increased use of reactive nitrogen and phosphorus by agricultural operations to produce food, fuel, and fiber for human benefit (Galloway et al 2008; Rabalais 2009; Ruddiman 2013) These anthropogenic sources of nutrients may increase eutrophication frequency and severity (Nixon 1995), which may create hypoxic or ‘dead zones’ in marine or estuarine environments (Turner et al 2008; Rabalais 2009), alter nutrient cycles (Justić et al 1995), and disrupt the trophic dynamics in food webs (Reish et al 1980; Conley et al 1993; Turner et al 1998). Anthropogenic inputs may reduce the ability of coastal wetlands to maintain soil elevation and keep pace with sea level rise

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