Abstract
The western basin of Lake Erie, the shallowest of the Laurentian Great Lakes in North America, is now plagued by harmful algal blooms annually due to nutrient discharges primarily from its basin. Water quality was impacted so significantly by toxic cyanobacteria in 2014 that the city of Toledo’s water supply was shut off, affecting hundreds of thousands of residents. A new agricultural land management approach, ‘wetlaculture (=wetland + agriculture)’, has a goal of reducing the need for fertilizer applications while preventing fluxes of nutrients to downstream aquatic ecosystems. A wetlaculture mesocosm experiment was set up on agricultural land near Defiance, Ohio, on the northwestern edge of the former ‘Great Black Swamp’. The mesocosms were randomly assigned to four hydrologic treatments involving two water depths (no standing water and ~10-cm of standing water) and two hydraulic loading rates (10 and 30 cm week−1 ). Nearby agricultural ditch water was pumped to provide weekly hydraulic loading rates to the mesocosms. During the two-year period, the net mass retention of phosphorus from the water was estimated to have averaged 1.0 g P m−2 in the wetland mesocosms with a higher hydraulic loading rate, while the highest estimated net nitrogen mass retention (average 22 g N m−2 ) was shown in the wetland mesocosms with 10 cm of standing water and higher hydraulic loading rate. Our finding suggests that hydrologic conditions, especially water level, contribute directly and indirectly to nutrient retention, partially through the quick response of the wetland vegetation community. This study provides valuable information for scaling up to restore significant areas of wetlaculture/wetlands in the former Great Black Swamp, strategically focused on reducing the nutrient loading to western Lake Erie from the Maumee River Basin.
| Original language | English (US) |
|---|---|
| Article number | 2509 |
| Journal | Water (Switzerland) |
| Volume | 13 |
| Issue number | 18 |
| DOIs | |
| State | Published - Sep 13 2021 |
Bibliographical note
Funding Information:Stream and Wetlands Foundation, Lancaster, Ohio.Thanks to the generous support on the project grant “Wetland-Agriculture ‘Wetlaculture’ Experiment in the Great Black Swamp Region of Ohio” (FGCU account 27582 from Stream and Wetlands Foundation, Lancaster, Ohio and their President Vince Messerly. The Lenhart family generously provided a corner of their farm property for this mesocosm study. We also appreciate the help provided on many occasions by William “Bruce” Clevenger, Agriculture and Natural Resources Extension Educator, The Ohio State University Extension Defiance County. His ability to repair the plumbing of the mesocosms after freezing damage in November 2018 allowed this study to continue for the second year. Bowling Green State University faculty and students, especially Angelica Vazquez Ortega, were generous in assisting with the mesocosm compound construction. Steve Fondriest from Fondriest Environmental in Fairborn, Ohio, designed a useful water delivery control system that reduced the number of necessary site visits. Special thanks to these friends: Jerry Pausch provided housing in Columbus for the first author, Mike Peppe assisted with site visits, Jiyoung Lee, Environmental Health Scientist in College of Public Health, The Ohio State University, provided lab space for preparing sampling bottles, pretreatment of plant samples and soil samples. Andrew Wilson and Li Zhang at our home lab in Naples, FL, helped track water sample packages and analyzed water samples.
Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
Keywords
- Agricultural runoff
- Hydrological loading rate
- Nitrogen
- Phosphorus
- Soil nutrient
- Treatment wetlands
- Wetland vegetation
- Wetland water level
