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Seagrass meadows are highly productive ecosystems that provide high-value ecosystem services and significantly contribute to carbon sequestration. Net community production (NCP) and community respiration (CR) in seagrass meadows are usually estimated from changes in oxygen concentration during in situ incubations in benthic chambers. Nevertheless, incubation chambers prevent water renovation, thus leading to an increase in pH and O₂ and a possible super-saturation inside the chamber, particularly during daytime at high irradiances. We tested the effect of incubation time on seagrass meadows NCP using benthic chambers in a pristine Posidonia oceanica meadow in Corsica, France. Incubations lasting 1.5–2, 3–5, 12, and 24 h were conducted along the day. The results showed that NCP closely follows dial irradiance pattern, with maximum NCP values (23.1 ± 2.8 mmol O₂ m⁻² h⁻¹ …