Shining light on priming in euphotic sediments: Nutrient enrichment stimulates export of stored organic matter

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Authors

Philip Riekenberg , Joanne Oakes, Bradley Eyre

Abstract

Estuarine sediments are important sites for the interception, processing and retention of organic matter, prior to its export to the coastal oceans. Stimulated microbial co-metabolism (priming) potentially increases export of refractory organic matter through increased production of hydrolytic enzymes. By using the microphytobenthos community to directly introduce a pulse of labile carbon into sediment, we traced a priming effect and assessed the decomposition and export of pre-existing organic matter. We show enhanced efflux of pre-existing carbon from intertidal sediments enriched with water column nutrients. Nutrient enrichment increased production of labile microphytobenthos-carbon which stimulated degradation of previously unavailable organic matter and led to increased liberation of “old” (6855 ± 120 years BP) refractory carbon as dissolved organic carbon. These enhanced DOC effluxes occurred at a scale that decreases estimates for global organic carbon burial in coastal systems and should be considered as an impact of eutrophication on estuarine carbon budgets.

DOI

https://doi.org/10.31223/osf.io/5auxz

Subjects

Biogeochemistry, Earth Sciences, Life Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Keywords

benthic, carbon, microalgae, microphytobenthos, nutrient enrichment

Dates

Published: 2020-05-26 01:17

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License

CC BY Attribution 4.0 International

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