Large benthic foraminifera as recorders of fine-scale coastal elemental variability

Anthropogenic activities and industrial growth significantly impact the marine environment, particularly in coastal areas where human activities intersect with the ocean, often leading to anthropogenic elemental enrichments. Monitoring geochemical signals in seawater, however, is challenging logistically and analytically. As an alternative, calcitic tests of benthic foraminifera provide a nature-based, readily available tool for monitoring environmental signals. This study aimed to demonstrate the applicability of shallow-water large benthic foraminifera as recorders of fine-scale coastal elemental variability, including elements derived from anthropogenic sources. The study focuses on the short coastline of the Gulf of Aqaba-Eilat, which exhibits high diversity in both anthropogenic levels and sources, making it an ideal case study. We report whole-test (ICP-MS) element-to‑calcium ratios in living specimens of the three most common LBF taxa: miliolids (Peneroplis pertusus, soritids) and rotaliids (Amphistegina), collected seasonally from six sites representing urbanized, industrial, and nature reserve areas along the 12-km Israeli coast. Miliolids consistently exhibit elevated El/Ca values and clearer spatial and temporal trends than rotaliids, highlighting their higher sensitivity as environmental recorders. Pb, Zn, and Cd ratios distinguish polluted from relatively clean sites, while Mn enrichment likely reflects freshwater input. Rare-earth elements exhibit a north-to-south enrichment gradient, a distinct seasonal pattern, and a positive gadolinium anomaly, which may reflect anthropogenic inputs from the city of Eilat. Overall, these findings demonstrate that elemental records of miliolid taxa are very effective bioindicators of localized and seasonal geochemical signals in coastal marine environments, offering a practical, nature-based approach to monitoring anthropogenic impacts.