Empirical Evaluation of Ecological Restoration Techniques for Degraded Mangrove Wetlands in Cross River State

This study empirically evaluates the effectiveness of different ecological restoration techniques for degraded mangrove wetlands in Cross River State, South South Nigeria, comparing assisted natural regeneration, active replanting using locally collected propagules, and hydrological restoration through tidal creek reopening as restoration interventions in oil-impacted and logging-degraded mangrove sites. Mangrove restoration is a global conservation and carbon sequestration priority, and Nigeria's substantially degraded mangrove estate presents significant restoration opportunities, but evidence-based assessment of which techniques are most effective in the Nigerian context is scarce. Experimental restoration plots were established at two degraded mangrove sites in Akpabuyo and Bakassi Local Government Areas, with three treatment types replicated at each site. Restoration success was monitored over thirty months using seedling survival rates, canopy height increment, stem density, benthic invertebrate community recovery, sediment organic carbon accumulation, and fish species richness in tidal creeks within restored areas. Results show that hydrological restoration via tidal creek reopening produces the fastest mangrove recovery, with natural regeneration achieving seedling densities of 2,800 per hectare within eighteen months at sites with an available propagule source. Active replanting achieves higher initial densities but shows 45 percent mortality by month eighteen at the oil-contaminated site, attributed to residual hydrocarbon toxicity. Assisted natural regeneration produces the best cost-to-outcome ratio at sites with low residual contamination. The study provides site condition-based guidance for mangrove restoration practitioners in South South Nigeria. Keywords: mangrove restoration, ecological restoration, Cross River State, tidal wetland, oil contamination.