Details:

Journal Title:
Journal of Geophysical Research: Biogeosciences
Personal Author:
Foster, S. Q. ; Fulweiler, R. W.
Foster, S. Q. ; Fulweiler, R. W. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; Sea Grant
OAR (Oceanic and Atmospheric Research) ; Sea Grant Less -
Sea Grant Program:
WHOI (Woods Hole Sea Grant)
Description:
Estuarine ecosystems are considered among the most valuable regions worldwide because of the wealth of ecosystem services they provide. Given their proximity to the land, they are also vulnerable to excessive nutrient inputs, which can lead to eutrophication and hypoxia. Water column hypoxia can dramatically alter sediment biogeochemistry, yet the response of specific processes varies widely. Predicting whether sediments are sources or sinks of ecologically and climatologically relevant nutrients and gases remains elusive, particularly for shallow coastal regions. In this study, we conducted experiments with sediments collected from Waquoit Bay (Massachusetts, United States) and measured dissolved nutrient and gas fluxes across the sediment-water interface to investigate the impact of water column hypoxia (defined here as dissolved oxygen ≤3 mg/L) on three important ecosystem functions: nutrient regeneration, removal of reactive nitrogen, and the regulation of greenhouse gases. Under hypoxia we observed variable responses in sediment biogeochemical cycling, including little to no change in important nitrogen cycling processes such as ammonium efflux and nitrogen removal through denitrification. As expected, low oxygen conditions stimulated sediment phosphate efflux. This caused nutrient ratios for both nitrogen to phosphorus and silica to phosphorus in the overlying water to decrease by 50%. Such changes can alter both the composition of water column primary producers as well as the rate of primary production. Hypoxia led to an almost 60% decrease in sediment nitrous oxide consumption but had little impact on sediment methane emissions. Taken together, these experimental results suggest sediment biogeochemical cycling has variable and dynamic responses to hypoxia.
Keywords:
[+]
Biogeochemistry Estuaries Hypoxia (Water)
Source:
JGR Biogeosciences 124(4): 737-758
DOI:
https://doi.org/10.1029/2018JG004663
Sea Grant Document Number:
WHOI-R-19-001
Document Type:
Journal Article
Rights Information:
Other
Compliance:
Library
Main Document Checksum:
[+]
urn:sha256:769ff4e55829c8a5c4bc1c511bba52a315bf22028da41dc09ae657df3802a9ff
Download URL:
https://repository.library.noaa.gov/view/noaa/43829/noaa_43829_DS1.pdf
File Type:

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