Differential vulnerability of mangrove species associated with thermoelectric power plant emissions revealed by the air pollution tolerance index

Mangrove ecosystems provide vital goods and services for sustainable living. Many forests are now facing anthropogenic pressures and air pollution. This study assessed the Air Pollution Tolerance Index (APTI) in mangrove forest species exposed to emissions from a thermoelectric facility, evaluating their responses to air pollution stress. The mangrove forest in Tampamachoco Lagoon (Ramsar site), in the Gulf of Mexico, is affected by surrounding localities and climate-forcing events, highlighting multiple stressors on mangroves. The study was conducted during the dry and rainy seasons across four mangrove species. Foliar biochemical parameters measured included total chlorophyll, pH, ascorbic acid, and relative water content. Overall, total chlorophyll and ascorbic acid were lower during the dry season and recovered during the rainy season. The concentration of atmospheric particulate matter was higher during the dry season than in the rainy season. Avicennia germinans was the most sensitive species in both seasons, exhibiting the lowest mean APTI (6.71), and is therefore proposed as a bioindicator of pollution. Rhizophora mangle showed an intermediate and relatively stable response (mean APTI, 7.95). Laguncularia racemosa exhibited intermediate to high tolerance (mean APTI of 7.61), while Conocarpus erectus showed the highest tolerance (mean APTI of 8.50). Our results revealed that APTI in mangroves is closely associated with leaf relative water content and ascorbic acid, a strong antioxidant. Proximity to the thermoelectric facility and pollutants from urban areas impose multiple stressors on mangroves in Tampamachoco Lagoon, threatening their health. Findings highlight APTI’s effectiveness as a biomonitoring tool in mangrove ecosystems exposed to atmospheric emissions and human activities.