Microplastics alter crystal growth in coral skeleton structures

Microplastics have emerged as a global environmental issue, inducing harmful effects on marine ecosystems and biodiversity. Their small size allows them to easily disperse across different ecosystems and enter the marine food chain, increasingly threatening coral ecosystems. This study hypothesizes that exposure to polyethylene microplastics alters the structure of coral skeletons. To test this, Briareum violacea corals were cultured under controlled conditions and exposed to polyethylene microplastics at concentrations of 0, 5, 10, 50, 100, and 300 mg/L for seven days. Skeletal structures were analyzed using X-ray diffraction, while inductively coupled plasma mass spectrometry was employed to assess changes in skeletal solubility and measure total calcium ion concentrations in seawater. The results revealed a transformation of coral skeletons from aragonite calcium carbonate crystals to amorphous calcium carbonate, as observed through X-ray diffraction analysis, with polyethylene microplastics causing this transformation to begin at a concentration of 10 mg/L. Additionally, skeletal solubility increased by 7.4-fold, as inferred from calcium ion concentrations measured by inductively coupled plasma mass spectrometry. Here we demonstrate that polyethylene microplastic exposure directly drives the degradation of coral skeletons, emphasizing the urgency of mitigating plastic pollution to safeguard coral ecosystems.