Seasonal hypoxia and nitrate depletion in water chestnut (Trapa natans) beds: Implications for nitrogen cycling.
- 1Department of Natural Resources and the Environment, Cornell University, Ithaca, New York, USA.
- 2Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York, USA.
Abstract
Dense beds of floating macrophytes can alter water quality by modifying dissolved oxygen (DO) and nitrogen (N) dynamics. Water chestnut (Trapa natans L.), a non-native annual macrophyte, forms extensive seasonal beds in freshwater systems in North America. The species is intensively managed to reduce negative impacts on native species, yet its effects on DO and nitrate (NO₃ ⁻) remain poorly studied. We quantified DO and NO₃ ⁻-N concentrations inside and outside of three riverine T. natans beds in New York over three growing seasons. In addition, we assessed denitrification using field-collected water and sediment in laboratory microcosm incubations. During summer months, DO of water from within T. natans beds was 76% lower on average (1.28 mg L⁻ ¹) compared to outside beds (5.43 mg L⁻ ¹). For NO₃ ⁻-N, concentrations averaged 0.45 (2017) and 0.11 (2018) mg L⁻ ¹ outside beds, but were depleted to 0.10 (2017) and 0.01 (2018) mg L⁻ ¹ within beds, 77%-88% lower than outside beds. In 2018, 60% of samples, mostly from within beds of T. natans, were below the analytical detection limit of NO₃ ⁻-N (0.02 mg L⁻ ¹). Laboratory microcosm incubations did not detect consistent N₂ production, despite experimental nitrate enrichment. Together, these results show that T. natans beds create seasonally hypoxic, nitrate-depleted conditions. However, weak and inconsistent N₂ production in our incubation experiments indicates that additional studies are needed to further assess the fate of nitrogen within T. natans beds and whether management may involve potential tradeoffs between habitat quality and nutrient cycling.
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BibTeX
@article{simmons2026seasonal,
title = {{Seasonal hypoxia and nitrate depletion in water chestnut (Trapa natans) beds: Implications for nitrogen cycling.}},
author = {Wade Simmons and Bernd Blossey and Michael Todd Walter},
journal = {Journal of environmental quality},
year = {2026},
month = nov,
doi = {10.1002/jeq2.70319},
url = {https://europepmc.org/article/MED/42972160},
note = {CC BY},
}
RIS
TY - JOUR
TI - Seasonal hypoxia and nitrate depletion in water chestnut (Trapa natans) beds: Implications for nitrogen cycling.
AU - Wade Simmons
AU - Bernd Blossey
AU - Michael Todd Walter
PY - 2026
DA - 2026/11/01
JO - Journal of environmental quality
DO - 10.1002/jeq2.70319
UR - https://europepmc.org/article/MED/42972160
AB - Dense beds of floating macrophytes can alter water quality by modifying dissolved oxygen (DO) and nitrogen (N) dynamics. Water chestnut (Trapa natans L.), a non-native annual macrophyte, forms extensive seasonal beds in freshwater systems in North America. The species is intensively managed to reduce negative impacts on native species, yet its effects on DO and nitrate (NO₃ ⁻) remain poorly studied. We quantified DO and NO₃ ⁻-N concentrations inside and outside of three riverine T. natans beds in New York over three growing seasons. In addition, we assessed denitrification using field-collected water and sediment in laboratory microcosm incubations. During summer months, DO of water from within T. natans beds was 76% lower on average (1.28 mg L⁻ ¹) compared to outside beds (5.43 mg L⁻ ¹). For NO₃ ⁻-N, concentrations averaged 0.45 (2017) and 0.11 (2018) mg L⁻ ¹ outside beds, but were depleted to 0.10 (2017) and 0.01 (2018) mg L⁻ ¹ within beds, 77%-88% lower than outside beds. In 2018, 60% of samples, mostly from within beds of T. natans, were below the analytical detection limit of NO₃ ⁻-N (0.02 mg L⁻ ¹). Laboratory microcosm incubations did not detect consistent N₂ production, despite experimental nitrate enrichment. Together, these results show that T. natans beds create seasonally hypoxic, nitrate-depleted conditions. However, weak and inconsistent N₂ production in our incubation experiments indicates that additional studies are needed to further assess the fate of nitrogen within T. natans beds and whether management may involve potential tradeoffs between habitat quality and nutrient cycling.
SN - 0047-2425
SN - 1537-2537
ER -