MEPS 752:51-68 (2025)  -  DOI: https://doi.org/10.3354/meps14752

ABSTRACT: Seagrass ecosystems rank among the most productive marine environments on the planet, hosting high cycling rates of many globally relevant elements. While the cycling of reactive oxygen species (ROS) has important links with other redox-related biogeochemical cycles (i.e. trace metals, carbon, nitrogen, and oxygen), the dynamics of ROS in seagrass ecosystems are poorly characterized. To assess the flux, decay rate, and fate of ROS, this study quantified rates of hydrogen peroxide (H₂O₂) production and decay through in situ incubations of seawater, algae Polysiphonia sp., and seagrass Zostera marina from a seagrass meadow near Woods Hole, MA, USA. Daytime net primary production values within incubations of Polysiphonia and Zostera ranged from 12.6 to 137.4 µmol O₂ g dry wt^-1 h^-1. By comparison, hydrogen peroxide dynamics were much more variable, with fluxes ranging from -272 to 150 nmol g dry wt^-1 h^-1, net production rates ranging from -2212 to 38000 nmol g dry wt^-1 h^-1, and decay rate constants ranging from 0.314 to 9.09 h^-1. These results suggest that seagrass meadows contribute to rapid and dynamic turnover of ROS. In separate incubations, tracing of isotopically labeled hydrogen peroxide (H₂¹⁷O₂) indicated that hydrogen peroxide decay was predominantly regulated by peroxidase-like activity (62 to 100%), suggesting that hydrogen peroxide serves primarily as an oxidant of likely various reduced substrates, which were not identified here. This study documents the rapid cycling and reductive decay pathways of hydrogen peroxide within seagrass ecosystems, laying the foundation for future studies of ROS cycling dynamics in these and other related shallow marine ecosystems.

KEY WORDS: Hydrogen peroxide · Seagrasses · Redox · Biogeochemistry · Reactive oxygen species

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Cite this article as: Grabb KC, Wankel SD, Sutherland KM, Bowman SH, Long MH, Hansel CM (2025) Hydrogen peroxide fluxes and fate in a temperate seagrass ecosystem. Mar Ecol Prog Ser 752:51-68. https://doi.org/10.3354/meps14752 Export citation Share:    Facebook - - Bluesky - linkedIn