Wetland Loss and its Ecological Consequences in the Cross River Floodplain

Wetland ecosystems along the Cross River floodplain in Nigeria's South South geopolitical zone provide critical ecological services including flood attenuation, carbon sequestration, freshwater fisheries support, and biodiversity habitat, yet sustained agricultural conversion, urban encroachment, and drainage alteration have reduced wetland extent substantially over recent decades. This study assesses wetland loss and associated ecological consequences in three local government areas of Cross River State: Calabar South, Biase, and Abi. Multi-temporal Landsat imagery from 2010, 2016, and 2023 was used to map wetland extent changes using a hybrid classification approach validated by 180 ground truth points. Ecological assessments at 20 wetland sampling sites measured species richness, vegetation structure, water quality parameters, and fish assemblage diversity as proxies for ecosystem health. Results document a 26 percent reduction in mapped wetland area over the thirteen-year study period, with the greatest losses recorded in Biase LGA due to palm oil estate expansion. Degraded wetland sites exhibit significantly reduced species richness, elevated nitrogen and phosphorus concentrations from agricultural runoff, and simplified fish assemblage structures dominated by pollution-tolerant species. Community fishing households report catch declines averaging 55 percent relative to conditions documented in oral historical accounts from the early 2000s. The study recommends legal designation of remaining high-value wetland patches as protected areas and integration of ecological compensation mechanisms into agricultural licensing frameworks in Cross River State. Keywords: wetland loss, Cross River, ecological services, land use change, South South Nigeria.