Soil physicochemical and bacterial properties of wetland ecosystems in south-south states of Nigeria

Wetlands are ecologically significant ecosystems that provide critical services including biodiversity conservation, flood regulation, and groundwater recharge. However, increasing pressures from agriculture, urbanization, and oil exploration have altered their ecological balance, particularly in the Niger Delta region of Nigeria. This study evaluated the physicochemical and microbiological properties of wetland soils across three South-South states—Rivers, Bayelsa, and Akwa Ibom—to assess their ecological status and management potential. Soil samples (0–15 cm depth) were collected in August 2021 and analysed using standard culture-dependent and physicochemical procedures, complemented with metagenomic profiling. Akwa Ibom and Bayelsa soils were dominated by sand, whereas Rivers soils contained relatively higher silt fractions. Slightly acidic conditions were observed across all sites, with pH ranging from 5.56 (Bayelsa) to 6.89 (Rivers). Total nitrogen content differed significantly, increasing from Bayelsa (7.81 mg/kg) to Akwa Ibom (18.31 mg/kg) and Rivers (59.65 mg/kg). Soil pH, organic carbon, and nitrogen strongly correlated with microbial community composition. Magnesium dominated the exchangeable bases, and electrical conductivity remained low across sites. Metagenomic sequencing revealed diverse microbial assemblages, with 14 bacterial phyla detected. Core taxa common to all sites included Proteobacteria, Actinobacteria, Planctomycetes, Verrucomicrobia, Firmicutes, Nitrospirae, Acidobacteria, and Chloroflexi, which collectively dominated the soils. Site-specific phyla were also observed, such as Dictyoglomi and Spirochaetes in Akwa Ibom, and Thermotogae and Paludibacteraceae in Bayelsa. Ignavibacteriae were detected in Akwa Ibom (24.96%) and Rivers (75.04%) but absent in Bayelsa. Overall, wetland soils in the South-South region of Nigeria exhibited slightly acidic conditions, low electrical conductivity, and diverse but site-specific microbial communities dominated by Proteobacteria. These findings highlight the influence of physicochemical parameters on microbial diversity and provide baseline data essential for wetland management, restoration, and sustainable utilization.