Benthic biofilm potential for organic carbon accumulation in salt marsh sediments

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: This is version 2 of this Preprint.


Download Preprint


Kendall Valentine, Abbey Hotard, Tracy Elsey-Quirk, Giulio Mariotti


Coastal salt marshes are productive environments with high potential for carbon accumulation and storage. Even though organic carbon in salt marsh sediment is typically attributed to plant biomass, it can also be produced by benthic photosynthetic biofilms. These biofilms, generally composed of diatoms and their secretions, are known for their high primary productivity and contribution to the basal food web. In this study, we conducted laboratory experiments to test (1) if biofilms can potentially accumulate carbon in marsh soil and (2) how different sedimentation rates affect the amount of carbon accumulation. Containers filled with a settled mud bed were inoculated with natural biofilms collected from a marsh surface and allowed to grow with favorable light exposure, nutrient supply, and absence of grazing. Mud was added weekly in different amounts, resulting in an equivalent sedimentation rate from 12 to 189 mm/yr. After 11 weeks, the sediment columns were sampled and analyzed for chlorophyll (chl a), loss on ignition (LOI), and total organic carbon (TOC). Chl a accumulation rates ranged from 123-534 mg/cm2/yr, organic matter accumulation ranged from 86-456 g/m2/yr, and TOC accumulation rates ranged from 31-211 g/m2/yr. All three metrics (chl a, organic matter, and TOC) increased with increased sedimentation rate. These results show that biofilms can potentially contribute to carbon accumulation in salt marsh soils. Furthermore, areas with high sedimentation rates have the potential for higher amounts of organic matter from biofilms in the sediment.



Biogeochemistry, Earth Sciences, Geomorphology


microphytobenthos, sedimentation, diatoms, blue carbon, laboratory experiment


Published: 2021-04-02 12:25

Last Updated: 2022-01-13 04:24

Older Versions

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:

Data Availability (Reason not available):
Data are available from the authors, and will be available in supplementary material in the published article.

Add a Comment

You must log in to post a comment.


There are no comments or no comments have been made public for this article.