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Downstream effects of beaver ponds on the water quality of New England first- and second-order streams

Authors

  • Leszek A. Błȩdzki,

    Corresponding author
    1. Environmental Studies Program, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA
    • Environmental Studies Program, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA.
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  • J. L. Bubier,

    1. Environmental Studies Program, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA
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  • L. A. Moulton,

    1. Environmental Studies Program, Mount Holyoke College, 50 College Street, South Hadley, MA 01075, USA
    2. Department of Horticulture, Oregon State University, 4017 Agricultural and Life Sciences Building, Corvallis, OR 97331, USA
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  • T. D. Kyker-Snowman

    1. DCR Division of Water Supply Protection, Quabbin Reservoir - 485 Ware Road, Belchertown, MA 01007, USA
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Abstract

Beaver, as allogenic ecosystem engineers, are capable of extensively altering surrounding habitats resulting in significant effects on stream water quality. This paper presents insight into downstream effects of beaver impoundments (both actively maintained and abandoned by beaver) and accumulated sediments on water quality, especially in protected watersheds serving as a drinking water supply. In a tributary un-inhabited by beaver compared to those with active beaver ponds, we found significantly (p < 0·001) lower concentrations of NO3[BOND]N (respectively: mean (standard error)) without beaver 0·11 (0·005) mg/l and with beaver 0·14 (0·002) mg/l), NH4[BOND]N (0·007 (0·002) and 0·24 (0·002) mg/l), dissolved organic carbon (DOC) (3·47 (0·081) and 8·37 (0·203) mg/l), chlorophyll (2·38 (0·066) and 6·96 (0·203) µg/l), and temperature (16·43 (0·101) and 19·85 (0·123) °C), but higher pH (7·17 (0·02) and 6·72 (0·022)), PO4 (0·20 (0·01) and 0·17 (0·014) mg/l) concentration, and dissolved oxygen (DO) saturation (100·8 (0·708) and 67·6 (1·74)%). Within the beaver ponds, we observed a high abundance of predatory zooplankton, which help to control algae and feed on detritus within the pond ecosystem. We intentionally breached an abandoned beaver dam in the field and conducted a sediment resuspension experiment in the laboratory to assess the potential for increases in turbidity and nutrients from beaver pond sediments as would be expected in the event of a catastrophic dam breach. We found that abandoned beaver ponds have a stronger influence on downstream water quality than actively maintained ponds owing to higher turbidity with finer sediments and sharply increased stream water temperature during a dam failure. Copyright © 2010 John Wiley & Sons, Ltd.

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