The Effects of Long-Term Nitrogen Enrichment on Estuarine Benthic-Pelagic Coupling

Mangan, Stephanie; Lohrer, Andrew M.; Thrush, Simon F.; Ellis, Joanne I.; Pilditch, Conrad A.

doi:10.3390/jmse10121955

Open AccessArticle

The Effects of Long-Term Nitrogen Enrichment on Estuarine Benthic-Pelagic Coupling

by

Stephanie Mangan

^1,*

,

Andrew M. Lohrer

²,

Simon F. Thrush

³,

Joanne I. Ellis

⁴

and

Conrad A. Pilditch

¹

School of Science, University of Waikato, Hamilton 3240, New Zealand

²

National Institute of Water and Atmospheric Research Ltd., Hamilton 3216, New Zealand

³

Institute of Marine Science, University of Auckland, Auckland 1142, New Zealand

⁴

School of Science, University of Waikato, Tauranga 3110, New Zealand

^*

Author to whom correspondence should be addressed.

J. Mar. Sci. Eng. 2022, 10(12), 1955; https://doi.org/10.3390/jmse10121955

Submission received: 18 November 2022 / Revised: 28 November 2022 / Accepted: 7 December 2022 / Published: 9 December 2022

(This article belongs to the Section Marine Ecology)

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Abstract

Biogeochemical cycling in the marine coastal zone regulates the availability of nitrogen and carbon within soft sediment habitats. However, these pathways are being fundamentally altered by anthropogenic increases in nutrient delivery. Few studies have incorporated long-term enrichment and ecological complexity (in situ experiments), restricting our ability to manage effectively and prevent ecological shifts. This study investigates the influence of sediment nutrient availability (at 3 levels, across 2 seasons) on biogeochemical cycling over a 20-month period in 4 estuaries. Overall, net denitrification rates were highly variable, ranging between 4 and 208 µmol N m⁻² h⁻¹. However, no increases were observed with increasing enrichment highlighting the limited capacity for nitrogen removal in response to large increases in bioavailable nitrogen. Additionally, macrofaunal communities and sediment trophic status were shown to have important influences on nitrogen processing. Overall, alterations to ecosystem relationships and the appearance of non-linear responses to increasing nutrient enrichment reveal the vulnerability of estuaries to increasing stressor loads owing to the increased likelihood of reaching a tipping point.

Keywords: denitrification; nitrogen; carbon; benthic fluxes; eutrophication; oligotrophic; nutrient enrichment

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MDPI and ACS Style

Mangan, S.; Lohrer, A.M.; Thrush, S.F.; Ellis, J.I.; Pilditch, C.A. The Effects of Long-Term Nitrogen Enrichment on Estuarine Benthic-Pelagic Coupling. J. Mar. Sci. Eng. 2022, 10, 1955. https://doi.org/10.3390/jmse10121955

AMA Style

Mangan S, Lohrer AM, Thrush SF, Ellis JI, Pilditch CA. The Effects of Long-Term Nitrogen Enrichment on Estuarine Benthic-Pelagic Coupling. Journal of Marine Science and Engineering. 2022; 10(12):1955. https://doi.org/10.3390/jmse10121955

Chicago/Turabian Style

Mangan, Stephanie, Andrew M. Lohrer, Simon F. Thrush, Joanne I. Ellis, and Conrad A. Pilditch. 2022. "The Effects of Long-Term Nitrogen Enrichment on Estuarine Benthic-Pelagic Coupling" Journal of Marine Science and Engineering 10, no. 12: 1955. https://doi.org/10.3390/jmse10121955

APA Style

Mangan, S., Lohrer, A. M., Thrush, S. F., Ellis, J. I., & Pilditch, C. A. (2022). The Effects of Long-Term Nitrogen Enrichment on Estuarine Benthic-Pelagic Coupling. Journal of Marine Science and Engineering, 10(12), 1955. https://doi.org/10.3390/jmse10121955

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

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The Effects of Long-Term Nitrogen Enrichment on Estuarine Benthic-Pelagic Coupling

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