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Updated: May 21, 2026
10:11
The Benthic Exchange of O2, N2 and Dissolved Nutrients Using Small Core Incubations
Published on: August 3, 2016
Changes in benthic nutrient sources within a wetland after hydrologic reconnection
James S Kuwabara1, Brent R Topping, James L Carter
1United States Geological Survey, Menlo Park, California, USA. kuwabara@usgs.gov
Environmental Toxicology and Chemistry
|June 19, 2012
Summary
Restoring wetlands by breaching levees released significant nutrients, with chemical changes taking years to stabilize. Aquatic invertebrates gradually colonized the area, indicating a long-term habitat transition.
Area of Science:
- Environmental Science
- Ecology
- Geochemistry
Background:
- Dam and levee removal is a common practice to restore hydrologic connectivity and ecosystem services.
- Agricultural use for decades had altered a historic wetland adjacent to Upper Klamath Lake and Agency Lake.
Purpose of the Study:
- To assess geochemical and biological changes after engineered levee breaches reconnected a lake to a long-farmed wetland.
- To understand the timescales of chemical and ecological recovery following wetland reconnection.
Main Methods:
- Engineered levee breaches were implemented to reconnect eutrophic lakes with a former wetland.
- Geochemical fluxes (DOC, SRP, ammonia, nitrate, iron, manganese) and benthic invertebrate colonization were monitored over three years.
- Benthic sources were compared to allochthonous (external) nutrient sources.
Main Results:
- The reconnected wetland acted as a significant benthic source for macronutrients and micronutrients, comparable to or exceeding external inputs.
- Dissolved organic carbon (DOC) flux initially peaked then decreased, while ammonia and soluble reactive phosphorus (SRP) fluxes became consistently positive.
- Nitrate fluxes diminished over time, and dissolved iron and manganese fluxes remained positive, contrary to some lab studies.
- Aquatic benthic invertebrate communities gradually established, resembling those in a nearby refuge wetland.
Conclusions:
- Hydrologic reconnection initiates multi-year, solute-specific chemical changes in restored wetlands.
- The reconnected wetland is transitioning into a permanent aquatic habitat, evidenced by invertebrate colonization.
- Water quality management strategies for wetland restoration must account for these multi-year recovery timescales.
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