5:15 PM - 6:45 PM
[BCG05-P03] Effects of polystyrene nanoparticles on benthic foraminifer Ammonia veneta
Keywords:Polystyrene nanoparticles, marine pollution, benthic foraminifera, toxicity
Plastic production has rapidly increased over the past 70 years, and at the same time the huge amount of their wastes has discharged into the oceans. Plastics are broken down to micro- and nano-sizes in the ocean and yield adverse effects on aquatic life. Polystyrene (PS), one of the most common uses of plastics, is dominantly accumulated on the sea-floor and indicates toxicity to benthos such as mussels and others. Benthic foraminifera, found from a wide area of the seafloor, take small-sized materials into its cell by using pseudopodia and build the calcareous by adding chambers in its entire life-cycle. Such characteristics of foraminifers are suitable for investigations of cytotoxicity and biomonitoring. In the previous exposure experiments with PS microparticles (MPs) and nanoparticles (NPs), foraminifers took PS MPs into cells (Grefstad, 2019) and showed a stress response in 1 ppm PS NPs (Ciacci et al., 2019), though there still remain unknown regarding long-term effect and threshold concentration of PS NPs for the survival of foraminifers. This study aimed to investigate the toxicity of PS NPs on the growth processes: growth, mortality, and malformation rates, by conducting long-term culture of benthic foraminifera with three types of artificial PS NPs.
We used clonal cultures of the benthic foraminifera Ammonia veneta for 5-week culture experiments in artificial seawater media supplemented with unmodified PS NPs, amine group-modified polystyrene (PS-NH2) NPs, and carboxyl group-modified polystyrene (PS-COOH) NPs, respectively. Each medium was prepared at 1 ppm and 100 ppm in addition to artificial seawater medium as a control. Each individual was photographed under an inverted microscope every week during the incubation period, and the increased number of chambers was evaluated as the growth rate. In addition, shells were collected at the end of the experiment and scanning electron microscope (SEM) observation and energy dispersive X-ray analysis (EDS) analysis of shell surfaces were performed. The growth rates of specimens treated in the low concentrations (1 ppm) of PS NPs media showed no significant differences from those in the control, whereas the growth rates of specimens in the PS-NH2 and PS-COOH NPs media were significantly lower than those of the control and unmodified PS NPs treated specimens in the high concentrations (100 ppm). Especially, all individuals died within two weeks in 100 ppm PS-NH2 and PS-COOH NPs media. In contrast, clonal reproduction was observed in 100 ppm of unmodified PS NPs as same as in the control. Our experiments showed that PS itself produce less toxicity in foraminiferal growth. The particle sizes of the modified PS (PS-NH2 and PS-COOH) NPs were almost same, though PS-NH2 and PS-COOH NPs are charged in positive and negative, respectively. Such surface electrification of NPs is known to enhance to toxicity to cell membrane and others. Moreover, the fluorescent substances are added to the modified PS NPs used in this study. The EDS analysis detected trace amounts of metallic elements from both PS-NH2 and PS-COOH, suggesting that metals were used as fluorescent probes. These metals could have toxic effect to foraminifers. Another interesting finding is that shell were deformed even in low concentration of unmodified PS NPs. Chamber formation of foraminifers could be impacted by PS NPs. We will need to investigate toxic effect of each PS NPs in future.
Ciacci, C., et al. (2019). Nanoparticle-biological interactions in a marine benthic foraminifer. Sci. Rep. 9(1):19441.
Grefstad, A.I. (2019) Marine benthic foraminifera and microplastics (accumulation and effects following short-and long-term exposure). Master thesis. University of Oslo.
We used clonal cultures of the benthic foraminifera Ammonia veneta for 5-week culture experiments in artificial seawater media supplemented with unmodified PS NPs, amine group-modified polystyrene (PS-NH2) NPs, and carboxyl group-modified polystyrene (PS-COOH) NPs, respectively. Each medium was prepared at 1 ppm and 100 ppm in addition to artificial seawater medium as a control. Each individual was photographed under an inverted microscope every week during the incubation period, and the increased number of chambers was evaluated as the growth rate. In addition, shells were collected at the end of the experiment and scanning electron microscope (SEM) observation and energy dispersive X-ray analysis (EDS) analysis of shell surfaces were performed. The growth rates of specimens treated in the low concentrations (1 ppm) of PS NPs media showed no significant differences from those in the control, whereas the growth rates of specimens in the PS-NH2 and PS-COOH NPs media were significantly lower than those of the control and unmodified PS NPs treated specimens in the high concentrations (100 ppm). Especially, all individuals died within two weeks in 100 ppm PS-NH2 and PS-COOH NPs media. In contrast, clonal reproduction was observed in 100 ppm of unmodified PS NPs as same as in the control. Our experiments showed that PS itself produce less toxicity in foraminiferal growth. The particle sizes of the modified PS (PS-NH2 and PS-COOH) NPs were almost same, though PS-NH2 and PS-COOH NPs are charged in positive and negative, respectively. Such surface electrification of NPs is known to enhance to toxicity to cell membrane and others. Moreover, the fluorescent substances are added to the modified PS NPs used in this study. The EDS analysis detected trace amounts of metallic elements from both PS-NH2 and PS-COOH, suggesting that metals were used as fluorescent probes. These metals could have toxic effect to foraminifers. Another interesting finding is that shell were deformed even in low concentration of unmodified PS NPs. Chamber formation of foraminifers could be impacted by PS NPs. We will need to investigate toxic effect of each PS NPs in future.
Ciacci, C., et al. (2019). Nanoparticle-biological interactions in a marine benthic foraminifer. Sci. Rep. 9(1):19441.
Grefstad, A.I. (2019) Marine benthic foraminifera and microplastics (accumulation and effects following short-and long-term exposure). Master thesis. University of Oslo.