Macaronesia, Rivers, Environmental Monitoring, Humans, Madeira, Mercury - analysis, Water Pollutants, Chemical - analysis, Methylmercury Compounds, Macaronésia, Macaronésia, Macaronésia, Macaronésia, Macaronésia, Macaronesian, Macaronésia, Macaronesian, Macaronésie, Macaronésia, Macaronesian, Macaronésie, Macaronésia, Macaronesian, Macaronésie, Macaronésia,...