Response of Benthic Foraminifera to Cadmium Pollution Assessed via Morphological and Metabarcoding Analyses

Benthic foraminifera are effective indicators of heavy metal contamination in marine ecosystems. Traditional methods for benthic foraminiferal identification and biodiversity assessment rely predominantly on stereomicroscopic analysis. However, this approach is time-consuming, labor-intensive, and cannot effectively identify small or morphologically similar species. In this study, we aimed to enhance the utility of benthic foraminifera as bioindicators. To this end, we investigated the responses of benthic foraminiferal communities to varying concentrations of Cd under controlled laboratory conditions using both morphological assessments and metabarcoding analyses. Cd exposure reduced the abundance of benthic foraminifera. High Cd concentrations led to Cd enrichment in foraminiferal tests and altered the contents of other elements. Quinqueloculina, Ammonia, and Miliammina exhibited tolerance to Cd, whereas Parasorites and Ovammina were more sensitive. This study provides an effective approach for evaluating the short-term effects of heavy metal pollution on benthic foraminiferal communities.