Seasonal cycle of benthic denitrification and DNRA in the aphotic coastal zone, northern Baltic Sea
Year of publication
2020
Authors
Hellemann, D.; Tallberg, P.; Aalto, S. L.; Bartoli, M.; Hietanen, S.
Abstract
Current knowledge on the seasonality of benthic nitrate reduction pathways in the aphotic, density stratified coastal zone of the Baltic Sea is largely based on data from muddy sediments, neglecting the potential contribution of sandy sediments. To gain a more comprehensive understanding of seasonality in this part of the Baltic Sea coast, we measured rates of benthic denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) monthly in the ice-free period of 2016 in both sandy and muddy aphotic sediments, northwestern Gulf of Finland. No anammox was observed. The seasonal cycle of denitrification in both sediment types was related to the hydrography-driven development of bottom water temperature. The seasonal cycle of DNRA was less clear and likely connected to a combination of bottom water temperature, carbon to nitrogen ratio, and substrate competition with denitrification. Denitrification and DNRA rates were 50–80 and 20% lower in the sandy than in the muddy sediment. The share of DNRA in total nitrate reduction, however, was higher in the sandy than in the muddy sediment, being (by ~50%) the highest DNRA share in sandy sediments so far measured. Our data add to the small pool of published studies showing significant DNRA in both cold and/or sandy sediments and suggest that DNRA is currently underestimated in the Baltic coastal nitrogen filter. Our results furthermore emphasize that the various environmental conditions of a coastal habitat (light regime, hydrography, and geomorphology) affect biogeochemical element cycling and thus need to be considered in data interpretation.
Show moreOrganizations and authors
University of Eastern Finland
Aalto Sanni-Leea
Publication type
Publication format
Article
Parent publication type
Journal
Article type
Original article
Audience
ScientificPeer-reviewed
Peer-ReviewedMINEDU's publication type classification code
A1 Journal article (refereed), original researchPublication channel information
Journal
Parent publication name
Volume
637
Pages
15-28
ISSN
Publication forum
Publication forum level
1
Open access
Open access in the publisher’s service
Yes
Open access of publication channel
Partially open publication channel
Self-archived
Yes
Other information
Fields of science
Geosciences; Environmental sciences
Keywords
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Publication country
Germany
Internationality of the publisher
International
Language
English
International co-publication
Yes
Co-publication with a company
No
DOI
10.3354/meps13259
The publication is included in the Ministry of Education and Culture’s Publication data collection
Yes