Microalgae colonization on some artificial polymers in experimental conditions

Abstract

The present work demonstrates the results of experimental studies of the character of microphyte fouling on the surface of plastic materials. The work is based on two laboratory experiments I and II and the field one (experiment III). Experiments I and II were established in laboratory conditions in crystallizers for 4 and 7 weeks. As a model for the experiment I, polyethylene terephthalate (PET) plates of two types were used: the plates taken from the marine environment from coastal decomposition (rough, EP) and untreated PET plastic (smooth, KP); for experiment II – low pressure polyethylene (LDPE) plates and untreated PET plastic. Glass plates were used as controls. The field experiment took place for 7 days in the coastal zone of the Gulf of Odessa. PET plates of different transparency and surface were used as a model. As a result of experiment I, the plates of rough plastic (EP) and glass (K) had the best fouling, the lowest parameters of the fouling on the plates with a smooth surface (KP). Significant differences in quantitative indicators of microalgae on the plates were detected only during the first exposure. As a result of changes in the properties of the plastic surface after being in the marine environment, it becomes more suitable for the formation of fouling in the laboratory (experiment I), forming a biomass of from 0.2·10‑2 mg·cm-2 to 4.0·10‑2 mg·cm-2. Laboratory experiment II showed a gradual increase in the quantitative indicators of phytoperiphyton on PET plates (from 0.01·10‑2 mg·cm-2 to 0.18·10‑2 mg·cm-2), and a decrease on LDPE plates (from 0.03·10‑2 mg·cm-2 to 0.001·10-2 mg·cm-2). These data are confirmed by the correlation coefficient: +0.9 (for PET) and -0.9 (for LDPE) for biomass. The development of microalgae was regulated by ciliates, which began to develop actively on 2–3 weeks of the experiment and used microphytes as food. The maximum number of ciliates was observed on LDPE plates. Weekly exposure of PET in field experiment III demonstrated that the primary settlements of microphytes are quite diverse and reached 28 species. The obtained data make a significant contribution to understanding the processes of interaction of plastic materials with microalgae and will be the basis for future research.