Inter-Research > MEPS > v681 > p53-69  
MEPS
Marine Ecology Progress Series

via Mailchimp

MEPS 681:53-69 (2022)  -  DOI: https://doi.org/10.3354/meps13913

Ocean acidification modifies the impact of warming on sediment nitrogen recycling and assimilation by enhancing the benthic microbial loop

Michelle N. Simone1,2,*, Joanne M. Oakes2, Kai G. Schulz2, Bradley D. Eyre2

1School of Science, Auckland University of Technology, Auckland 1010, New Zealand
2Centre for Coastal Biogeochemistry, Faculty of Science and Engineering, Southern Cross University, Lismore 2480, NSW, Australia
*Corresponding author:

ABSTRACT: Nitrogen that has been recycled in the benthos supports high rates of primary and secondary production in estuaries. However, little is known about the effect of future climate on benthic nitrogen recycling and assimilation. An ex situ core incubation was used to assess the impact of combinations of warming (8°C range) and ocean acidification (OA) (i.e. increased pCO2 and decreased pH) on ammonium (NH4+) and nitrate/nitrite (NOx) fluxes and 15N-nitrate assimilation in shallow unvegetated estuarine sediments. Dissolved inorganic nitrogen (DIN = NH4+ + NOx) fluxes were significantly affected by the interaction of warming and OA, highlighting the importance of considering combined stressor treatments when investigating ecosystem responses to future climates. Warming alone increased DIN efflux from the sediments. At current mean ambient temperatures (23°C) and below (Δ-3°C), OA significantly increased DIN effluxes, but there was little to no effect of OA on DIN fluxes at warmer temperatures (Δ+3°C and Δ+5°C). OA reduced the 15N assimilation/retention of the sediments across all temperatures, suggesting that nitrogen retention in bacterial biomass was reduced, despite OA also increasing primary productivity. As such, under the projected future climate of ~3°C warming and doubling of pCO2 (~1000 µatm), unvegetated estuarine sediments are likely to have a more rapid turnover of DIN driven by greater microphytobenthos production and recycling.


KEY WORDS: Ocean acidification · Marine sediments · Climate change · Microphytobenthos · Estuaries · Nitrogen cycling


Full text in pdf format
Supplementary material 
Cite this article as: Simone MN, Oakes JM, Schulz KG, Eyre BD (2022) Ocean acidification modifies the impact of warming on sediment nitrogen recycling and assimilation by enhancing the benthic microbial loop. Mar Ecol Prog Ser 681:53-69. https://doi.org/10.3354/meps13913

Export citation
Mail this link - Contents Mailing Lists - RSS
Facebook - - linkedIn