Environmental Drivers of Sediment Microbial Community Structure Across Restored, Altered, and Reference Mangroves in Las Calderas Bay, Dominican Republic

Mangrove reforestation efforts in the Caribbean are expanding, yet success is still primarily measured by tree survival and canopy cover, rather than sediment microbiome recovery. A study in the Las Calderas Bay, Dominican Republic, analyzed sediment prokaryotic communities in reference, reforested, and altered mangroves using 16S rRNA gene metabarcoding and various measurements.

Reference sediments had significantly more organic carbon, higher C/N ratios, and lower pH compared to reforested and altered sediments. The reference community was more diverse and even, differing from the disturbed stands, while the reforested and altered communities were statistically indistinguishable. Disturbed sediments were dominated by Cyanobacteriota, tracking high pH, whereas reference sediments were enriched in Chloroflexota, Thermodesulfobacteriota, and Thermoproteota, linked to anaerobic degradation of complex organic matter and sulfate reduction.

Depth-structured communities were separated into surface and subsurface layers, with sediment organic carbon and nitrogen being the only significant constraints in distance-based redundancy analysis. The findings suggest that within a few years of planting, reforestation had not restored the carbon-rich, anaerobic sediment habitat of the reference forest.

The authors propose that sediment organic carbon and microbial community structure should be considered as complementary indicators for mangrove restoration monitoring in the Caribbean.