Variation of CO2 fluxes, net ecosystem production, and calcification in tropical waters of seagrass and coral reef

Carbonate system alteration in Indonesia's seagrass and coral reef ecosystems must be better understood. Changes in CO2 fluxes, ecosystem production, and calcification can impact the availability of resources and habitats for seagrass and coral reef species, which can have cascading effects on the overall health and diversity of marine ecosystems. The study aims to identify diurnal and seasonal CO2 flux, net ecosystem production (NEP), and net ecosystem calcification (NEC) in the tropical waters (Sire Bay, Lombok) around seagrass and coral reef ecosystems. Field sampling was conducted in two seasons and measured the seawater carbonate system and physicochemical characteristics. We found a significant difference in CO2 flux between seagrass and coral reefs in April but not for NEP and NEC in April or October. Both ecosystems act as CO2 sources in April, and CO2 sinks in October. The NEP of coastal water tends to be autotrophic in April and heterotrophic in October. The calcification rate was inversely proportional to the NEP, where the NEC was higher in October than in April. There was a low relationship between CO2 flux and NEP and NEC, indicating that changes in CO2 flux do not directly affect NEP and NEC in Sire Bay waters.