Premium
Influence of settling organic matter quantity and quality on benthic nitrogen cycling
Author(s) -
Albert Séréna,
Bonaglia Stefano,
Stjärnkvist Nellie,
Winder Monika,
Thamdrup Bo,
Nascimento Francisco J. A.
Publication year - 2021
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.11730
Subject(s) - benthic zone , denitrification , plankton , nitrogen cycle , organic matter , pelagic zone , environmental science , mineralization (soil science) , water column , nutrient cycle , nitrate , environmental chemistry , sediment , cycling , nutrient , settling , oceanography , nitrogen , chemistry , ecology , environmental engineering , biology , soil science , geology , soil water , history , paleontology , organic chemistry , archaeology
Coastal sediments are major contributors to global carbon (C) mineralization and nutrient cycling and are tightly linked to processes in the pelagic environment. In this study, we aimed to investigate the regulating potential of quantity and quality of planktonic organic matter (OM) deposition on benthic metabolism, with a particular focus on nitrogen (N) cycling processes. We simulated inputs of spring (C : N 10.9) and summer (C : N 5.6) plankton communities in high and low quantities to sediment cores, and followed oxygen consumption, nutrient fluxes as well as nitrate reduction rates, that is, denitrification and dissimilatory nitrate reduction to ammonium for 10 d. Our results demonstrate the primary importance of OM quality in determining the fate of organic N once it settles to the sediment surface. Settling of N‐rich summer plankton material resulted in a ∼ twofold lower denitrification efficiency (40–56%) compared to N‐poor spring plankton (88–115%). This indicates that N‐rich plankton deposition favors recycling of inorganic nutrients to the water column over N‐loss via denitrification. OM quantity was positively related to mineralization activity, but this neither directly affected N fluxes nor denitrification activity, highlighting the complex interplay between the OM quantity and quality in regulating N cycling. In light of these new findings, we support the use of simple qualitative indicators such as C : N ratio of OM to investigate how future changes in benthic‐pelagic coupling might influence N budgets at the sediment–water interface.