Abstract:
This study examines daily carbon dioxide (CO₂) flux dynamics in a tropical
seaweed farming system to evaluate its potential role in blue carbon
sequestration. CO₂ flux measurements were conducted over the 40-day
cultivation period using a static floating acrylic chamber. Daily CO₂ flux
analysis was based on measurements conducted on cultivation days 20, 21,
and 23, with gas samples collected at 6-hour intervals (morning, midday, and
night). Samples were withdrawn using syringes, transferred into 10mL
vacuum blood tubes, protected from direct sunlight, and analyzed using gas
chromatography. CO₂ fluxes (mg CO₂ m⁻² min⁻¹) were calculated based on
changes in gas concentration, chamber volume, surface area, and
temperature. The results revealed a clear diurnal pattern, with negative CO₂
fluxes (uptake) observed during the morning and midday and positive fluxes
(emission) occurring at night. This pattern reflects photosynthetic activity
driven by daylight, confirming the role of seaweed as a photo-autotrophic
organism that assimilates CO₂ into biomass, supported by the availability of
dissolved nitrogen and phosphate. Over the cultivation period, CO₂ fluxes
tended to become more negative, indicating enhanced carbon uptake
associated with biomass growth. In comparison, non-seaweed areas
exhibited lower but still negative CO₂ fluxes, likely attributable to
phytoplankton photosynthesis. These findings indicate that tropical seaweed
farming systems can function as effective carbon sinks, supporting their
inclusion in blue carbon initiatives and coastal climate mitigation strategies.
