Nutrient amendment does not increase mineralisation of sequestered carbon during incubation of a nitrogen limited mangrove soil

► We measured microbial activity in soils from Avicennia and Rhizophora mangrove stands. ► We tested the effect of nutrient inflow on microbial growth and CO2 production rates. ► Microbial activity is primarily carbon- and not nutrient-limited in both systems. ► Nitrogen stimulated glucose degradation but inhibited soil carbon mineralisation. ► The results indicate unchanged decomposition of mangrove SOC upon wastewater inflow.