Beavers as Ecosystem Restoration Engineers in a Legacy Mined Landscape
Abstract
Historical mining activity continues to impact aquatic ecosystems in many ways long after the mine has been abandoned. Acid mine drainage, which results when sulfuric rocks are exposed to water, lowers the pH of nearby streams and ponds. This acidic water frequently carries high concentrations of dissolved metals, including iron, aluminum, arsenic, and lead. Mining also disturbs the soil profile, removing the topsoil which alters shallow subsurface flowpaths and reduces the pool of terrestrial nutrients, such as carbon, available to the aquatic ecosystem.
The important role of beavers as ecological engineers has been increasingly recognized as their population grows in North America. Beavers create wetlands which have been shown to improve biodiversity, help landscapes weather drought conditions, and limit the spread of wildfires. A legacy coal mining site in eastern Ohio, which was abandoned before the Surface Mine Control and Reclamation Act, is now the site of a string of beaver ponds. Our goal was to test whether beaver ponds were aiding the ecosystem recovery from acid mine drainage. We collected water samples throughout the beaver pond system and analyzed the macroinvertebrate populations. At the start of the beaver ponds the pH of the stream ranged from 3 - 4.5 with large concentrations of sulfate, iron, aluminum, and magnesium. Both iron and aluminum particulates can be observed precipitating from the stream and within the beaver ponds. Within 1 km, after the water has passed through at least 5 beaver ponds, the pH of the stream is up to 7 - 7.5 and the water is clear, with no visible metal precipitates. However, in spite of this apparent improvement in water quality, the carbon and nutrient concentration of this stream stays very low throughout the stretch, with minimal evidence of decomposition of plant material. Our initial findings suggest that while beaver ponds improve some aspects of water quality on legacy mine land, they likely cannot fully restore ecosystem function.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H33J2053G
- Keywords:
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- 1803 Anthropogenic effects;
- HYDROLOGY;
- 1831 Groundwater quality;
- HYDROLOGY;
- 1834 Human impacts;
- HYDROLOGY;
- 1871 Surface water quality;
- HYDROLOGY