[Combined Effects of Erythromycin and Nutrients on Microalgae in Seawater]

A large number of antibiotics and their metabolites eventually enter the ocean, and their potential threat to marine ecosystems demands attention. In this study, Karenia mikimotoi, Prorocentrum donghaiense, and Skeletonema costatum were selected to investigate the effects of different concentrations of erythromycin and nutrients on microalgae biomass, photosynthetic pigment contents, protein contents, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content. The possibility of whether erythromycin and nutrient limitation can have combined effects on microalgae was explored, and under different nutritional conditions, the impact of erythromycin on marine ecology was evaluated. The study found that nutrient limitation reduces the tolerance of Karenia mikimotoi, Prorocentrum donghaiense, and Skeletonema costatum to erythromycin. Erythromycin in the experimental range (0-1000 μg·L^-1) had no significant effect on the growth of Karenia mikimotoi. However, high concentrations of erythromycin (≥100 μg·L^-1)significantly inhibited the growth of Prorocentrum donghaiense and Skeletonema costatum. The sensitivity of Skeletonema costatum was the most pronounced.