A GIS and field-based assessment of the ecological consequences of illegal mining (galamsey) on blackfly breeding sites in Ghana: implications for the sustainable development goals

BACKGROUND: The Ofin River basin has historically supported Simulium blackfly breeding, vectors of Onchocerca, yet recent Programme reports have noted a sharp decline in monitored populations. With illegal artisanal mining (galamsey) expanding around the basin, this study assessed how associated ecological changes may influence habitat suitability for blackfly breeding across three riverine communities (Adwuman, Buabenso, and Kyekyewere). METHODS: Water discharge and quality were assessed through field measurements and laboratory analyses of pH, electrical conductivity, turbidity, colour, total suspended solids (TSS), and total dissolved solids (TDS). Satellite imagery from 2008, 2017, and 2022/23 was analysed using Iso Cluster Unsupervised Classification algorithm (ISODATA), Principal Raster Components Analysis (PRCA) and the Normalized Difference Vegetation Index (NDVI) to quantify transitions and vegetation health using ArcGIS Pro. RESULTS: /s) and quality analysis showed differences in key parameters. Adwuman's pH was 6.98, conductivity (145.5 µS/cm), turbidity (3392.5 NTU), colour (3375 Hz) and TSS (3630 mg/L). Buabenso had a pH of 6.98, conductivity 146.75 µS/cm, turbidity 3525 NTU, colour at 3812.5 Hz and TSS of 3857.5 mg/L. Kyekyewere recorded the lowest pH (6.95) and conductivity (145.25 µS/cm), but the highest turbidity (3725 NTU), colour (4175 Hz) and TSS (4342.5 mg/L). Forest cover declined by 10.72, 7.41, and 8.80 percentage points in Adwuman, Buabenso, and Kyekyewere, respectively, while light vegetation increased by 15.71, 15.00, and 18.93 points. Water coverage expanded by 10.81, 6.12, and 5.26 percentage points across the communities, indicating hydrological alteration. NDVI revealed widespread declines in vegetation health and density, particularly near mining zones. CONCLUSION: The combined effects of extreme sedimentation, vegetation degradation and riparian disturbance suggest ecological conditions that are increasingly unsuitable for blackfly breeding in the Ofin River basin. The disruptions also threaten food security, clean water access and ecosystem integrity, with implications for achieving SDG 2, 3, 6, and 15. Strengthened River management, reforestation of degraded riparian areas, enforcement against illegal mining and community-based monitoring are needed to restore ecological function and safeguard both biodiversity and public health.