The invisible impact of tourism: organic UV filters in the coastal ecosystem of a remote Atlantic island

Abstract

Coastal tourism and recreational activities contribute to the release of Personal Care Products, including sunscreens, which contain organic ultraviolet filters (oUVFs), increasingly recognised as contaminants of emerging concern in marine ecosystems. Oceanic islands offer natural laboratories for studying these compounds due to their isolated ecosystems and varying levels of human pressure. This study investigates the occurrence and distribution of oUVFs in seawater, sediments, and biota from three locations in the Madeira Archipelago with varying human influence, sampled during both high and low tourist seasons. Solid-phase extraction (SPE) and microwave-assisted extraction (MAE) were used as extraction methods, followed by UHPLC-MS/MS for identification and quantification. Eight of 11 target compounds were detected in at least one matrix. Total maximum concentrations reached 70.61 ng/L in seawater, 299.8 ng/g d.w. in algae, 472.2 ng/g d.w. in fish, and 651.33 ng/g d.w. in zooplankton. Detection frequencies and levels were highest at the site with the most significant anthropogenic pressure during the high tourist season. Zooplankton showed the highest accumulation levels, followed by herbivorous fish and red algae, while no oUVFs were detected in mesopredators and some invertebrates. Contamination was associated with proximity to shore and direct inputs linked with anthropogenic pressure. However, the oceanographic (e.g., currents, tides) and geological characteristics (rocky reefs) of oceanic islands must also be considered, as they can affect the environmental fate and distribution of oUVFs across different matrices. These findings highlight the need to monitor oUVFs in marine environments and identify susceptible species to improve ecological risk assessment and regulatory actions.