Assessment of responses of cultured benthic foraminiferal communities to copper pollution through environmental RNA...

Copper (Cu) is an essential trace element and can accumulate in sedimentary environments. However, beyond a certain concentration threshold, Cu can pose toxicity risks to biota. Benthic foraminifera are widely distributed and exhibit characteristics such as high biodiversity, short life cycle, good preservation potential, and high pollutant sensitivity, making them good bioindicators. In this study, we investigated the responses of benthic foraminiferal communities to various Cu concentrations through environmental RNA metabarcoding under controlled laboratory conditions. Some foraminiferal genera-Glandulina, Pyrgo, Quinqueloculina, Sorites, and Vellaria-exhibited sensitivity to high Cu concentrations. Other genera-Ammonia, Operculina, Reophax, Bolivina, Glabratella, Miliammina, and Parasorites-displayed tolerance to high Cu concentrations. Moreover, high Cu levels led to reduced living benthic foraminifera abundance and interspecific interactions, albeit without inducing test deformities. Our findings provide a novel and efficient approach for exploring the responses of benthic foraminiferal communities to heavy metal pollution.