Tropical wetlands can play a more active role in carbon emissions than their temperate counterparts due to higher temperatures and precipitation. Specifically, tropical wetlands account for up to 2/3 of global methane (CH4) emissions from wetlands globally and are substantial sources of carbon dioxide (CO2). Tropical coastal wetlands are also experiencing global changes, such as salinization due to sea level rise, that can either enhance or inhibit ecosystem processes that influence carbon emissions. To evaluate how sea-level rise influences carbon cycling in tropical coastal wetlands, we performed short-term (7 day) incubations with sediment and surface water from two coastal freshwater wetland sites with different background environmental conditions (low and high salinity) under two different ‘sea salt’ amendments: low conductivity (+1000µS/cm) and high conductivity (+2,000µS/cm). We measured CO2 and CH4 concentrations at 0, 1, 3, and 7 days. At the end of the incubations, we measured the dry sediment weight and the ash-free dry mass to obtain organic matter (OM) content. We also monitored conductivity and dissolved oxygen (DO) with high-frequency sensors in each wetland for one month. Wetland sediment OM content was 64% in the low salinity wetland and 32% in the high salinity wetland. In both wetlands, potential CO2 production rates decreased over the incubation period and were not influenced by salinization treatments. In the low OM/high salinity wetland CH4 production rates increased over the incubations and were lower in the increased salinity treatments. In the high OM/low salinity wetland, we saw CH4 consumption, which decreased over the incubation. Both of these wetlands are influenced by tidal patterns and DO had strong diel patterns in the low OM wetland while it was generally anoxic and stable (<1mg/L) in the high OM wetland. These results suggest that salinization will have variable influence on carbon cycling in coastal wetlands depending on their OM concentrations and background environmental conditions.