Assessing the Current Alterations to the Estuarine Ecosystem in Southwest Nigeria

Abstract

The estuarine ecosystem provides services that are economically and ecologically indispensable, and these services offer support to human well-being. However, uncontrolled human activities have altered the ecosystem goods and services provision, thus resulting in numerous irreversible ecological losses in the wetlands. Globally, studies have used many approaches and paradigms to manage estuarine ecosystems, yet a limited management mechanism exists in the Nigerian estuarine ecosystems. This study investigated the human dimensions of the alterations of the estuarine ecosystems in Southwest Nigeria over 20 years and used the result to inform decision-making. This study also used remotely sensed datasets (Operational Land Imager and Thermal Infrared (OLI/TIRS) and Enhance Thematic Mapper (ETM)) from the United State Geological Survey (USGS) Earth Explorer as references to determine the estuarine ecosystems coverage and loss. The reference datasets were combined and overlaid on the Nigerian wetland data to conduct a change analysis. Maximum Likelihood Classification in ArcGIS was conducted to determine the ecosystem coverage and loss. The study also conducted a qualitative assessment of the concerned management agencies to understand the questions of the environmental, ethical, governance, economics, decision making and policy implementation that shape estuarine ecosystems management in the study area. The result of this study indicates that 6405 hectares (38.1%) of the estuarine coverage in 2001 has been depleted in 2021, and management activities are traditional, nonsequential, and deficient. The drivers of alterations identified are mainly anthropogenic activities and climate change. The implications include loss of valuable fish species, pollution, habitats and biodiversity loss. Therefore, this study recommended the Ecosystem-Based Management approach to determine all essentials of the success or failure of ecosystem goods and services supply, resource use efficiency, and stability of estuarine ecosystems in Southwest Nigeria.