Uptake and Egestion of Polyhydroxyalkanoate Microbeads in the Marine Copepod Nitocra lacustris pacifica

Petrochemical-based microplastics are widely distributed and abundant in the marine environment, and they have become a global economic and environmental concern. Microplastics are mistakenly ingested by zooplankton as food, subsequently disrupting the biological process of zooplankton, a crucial food source for many secondary consumers. Research has led to the development of biodegradable plastics, such as polyhydroxyalkanoate (PHA), to remediate this problem. This study aims to evaluate the ingestion and egestion of PHA microbeads by the Nitokra lacustris pacifica copepod. The polymer P(3HB) produced from Massilia haematophila UMTKB-2 was used to develop PHA microbeads. The PHA microbeads were then added to copepod cultures to study the ingestion of the PHA microbeads and its effects on the copepods. The copepods were viewed under an inverted fluorescence microscope to confirm the presence of the PHA microbeads in their digestive tracts and faecal pellets. The percentage of PHA microbeads ingested by the copepods and their incorporation in faecal pellets were higher, > 70% and > 80%, respectively, after being exposed for 24 h and three days were required to fully egest the microbeads. However, no mortality was observed in this short-term incubation experiment.