Necromass, a persistent complex of sticky dead microbes across matrices in soil, play key role towards stable organic carbon stock for tackling climate change. The land-ocean boundary system across South Asia harbors diverse coastal biotopes with limited available information on microbial residual carbon storage and its impact on benthic community. To address this research gap, microbial cell wall biomarkers were characterized from mangroves of Bay of Bengal to assess microbial blue carbon. It was found that microbial necromass carbon is the key fraction of soil organic carbon (24.92%) within first 20 cm of top-soil compared to 16.02 % in 0-10 cm implying rapid turnover. Fungal derived residual carbon was the major contributor to SOC in 0-10 cm. Highly abundant soil fungi and large biomass attributed for major contribution as residual carbon in SOC than bacterial dead counterparts. The ratio of fungal necromass carbon/bacterial necromass carbon varied from 7.49 to 5.81 for 0-10 cm and 0-20 cm respectively. Fungi is the dominating component that can decompose complex substrates with consequences for microbial carbon pump driven SOC stabilization. The pH and total nitrogen stimulated microbial blue carbon accumulation. The microbial carbon pump seems to influence abundance of benthic eukaryotic communities such as foraminifera between 0-4 cm depth profiles (total abundance 305 individuals per 10 cc). The top layer (0-2 cm) had higher number of benthic foraminifer taxa (11). Based on findings, pH is a dominant driver of carbon dynamics in mangrove sediment and also influences the benthic eukaryotic organismal communities with possible consequences for secondary production.
 

necromass, South Asia, microbial carbon, benthic community