Physiological responses of Gutweed Ulva intestinalis (Linnaeus, 1753) exposed to high-density polyethylene microplastics

Pollution by microplastics (MPs) in aquatic environments remains a global concern. Despite recent developments, there is a knowledge gap in the implications of MP pollution on autotrophic aquatic organisms such as macroalgae. The response of green macroalgae species, Ulva intestinalis to high-density polyethylene microplastics (HDPE-MPs) was investigated. Scanning Electron Microscopy (SEM) and Attenuated Total Reflectance - Fourier Transform Infrared (FT-IR) Spectroscopy showed adherence of HDPE-MPs onto surfaces of U. intestinalis. The following parameters were assessed: growth rate, chlorophyll content, and protein carbonyl content. The 14-day exposure assay entailed one control group (0 mg/L) and the HDPE-MP treated group (100 mg/L). The treatment of HDPE-MPs in U. intestinalis has a significant effect on the aforementioned parameters (p < 0.05). The treated group showed a lower growth rate (1.24 vs. 3.15 %) and chlorophyll content (0.705 vs. 0.911 mg/g), and higher protein carbonyl content (1.654 vs. 0.571 nmol DNPH/mg protein). These findings suggest that HDPE-MP exposure can negatively affect physiological processes in U. intestinalis. Subsequently, this study features the potentially adverse effects of MPs on autotrophic aquatic organisms.