Changes in the Development and Reproductive Output of Nitokra lacustris pacifica (Crustacea: Copepoda) Yeatman, 1983 Under Short and Long Term Exposure to Synthetic and Biodegradable Microbeads

Microplastics have become a significant problem in the marine environment where a wide range of marine organisms can ingest them. Biodegradable plastics or bioplastics, which are now being widely sourced as an alternative to conventional non-biodegradable plastics, are also known to breakdown into microparticles. This study aims to investigate the interaction between two types of microbeads towards the reproductive and development functions of the harpacticoid copepod, Nitokra lacustris pacifica. Polystyrene (PS) microspheres were used as the synthetic treatment, while microbeads produced from bacterial polyhydroxyalkanoates (PHA) copolymer were used as the biodegradable treatment. Exposure to microplastics at concentrations of ~ 700 microbeads mL−1 exhibited a significant reduction in algal (Nannochloropsis sp.) ingestion. No differences were observed egg production rate (9.3–10.5 eggs fem−1 day−1), but nauplius production was significantly reduced in PS microbead treatment (40%). Development time of N. lacustris pacifica from egg to adult in control (Nannochloropsis sp.) and PHA microbead treatments was significantly shorter (10.7 and 11.2 days, respectively) than in PS microbead treatment (14 days). Similarly, during the extended exposure, no differences were observed in the egg production rate, but nauplius production was significantly affected (< 14%) compared to control and PHA treatments (> 60%).