Assessment of the impacts of trace metals on benthic foraminifera in surface sediments from the northwestern Taiwan Strait

• We report the spatial patterns of trace metals and benthic foraminifera.
• The overall contamination of trace metals is very low to low.
• Trace metals exhibit a strong affinity with fine-grained sediment.
• Species respond specifically to environmental variables.

The distribution patterns of foraminiferal assemblages in relation to trace metals, sediment grain size, and calcium carbonate were studied in 232 surface sediments collected from the northwestern Taiwan Strait. Multivariate analyses of biotic and abiotic data revealed a separation of near-shore, coastal, and deep-water zones. The modified degree of contamination suggested that the overall contamination was very low to low. Trace metals were enriched in the near-shore and outside bays. Their distribution was likely determined by sediment transport pathways and hydrodynamic conditions. High metal concentrations co-occurred with a low density and diversity of foraminiferal assemblages. Pb, Ba, organic carbon, Ga, Zn, Cu, and Co had a positive correlation with near-shore assemblage, whereas Cr and Ni positively related to the deep-water assemblages. Some calcareous foraminifera were favored by CaCO3, Sr, and sand. This study highlights species’ responses that are specific to environmental variables.