Comparison of Microbial and Heavy Metal Contents in Soils and Roots under Mangrove Forest Stands with Different Levels of Pollution in the Niger River Delta, Nigeria

Oil and gas exploration in the Niger Delta, has resulted to increased heavy metal contamination. It is thus postulated that increased heavy metal will lead to decreased microbial content in soil and root. To test this hypothesis ten replicates each of soil and root samples were collected from already established sites. Samples were sent to the laboratory for analyses of heavy metals (spectrophotometric method), total hydrocarbon (colorimetric method) and microbial (Sabouraud Destrose Agar) contents. The result indicates that bacterial population outnumbered fungal population in soils and roots. Similarly, there were significant differences in both microbial and heavy metal contents between highly and lowly polluted plots (p = 0.0001) and between polluted and non-polluted locations (p = 0.0001). Heavy metal has negative linear relationship with microbial content. As heavy metal increases the microbial activities reduces with implication on litter decomposition and nutrient cycling, which may eventually affect mangrove growth and development.