Exposure of marine mussels Mytilus spp. to polystyrene microplastics: Toxicity and influence on fluoranthene bioaccumulation

Abstract

The effects of polystyrene microbeads (micro-PS; mix of 2 and 6 μm; final concentration: 32 μg L(-1)) alone or in combination with fluoranthene (30 μg L(-1)) on marine mussels Mytilus spp. were investigated after 7 days of exposure and 7 days of depuration under controlled laboratory conditions. Overall, fluoranthene was mostly associated to algae Chaetoceros muelleri (partition coefficient Log Kp = 4.8) used as a food source for mussels during the experiment. When micro-PS were added in the system, a fraction of FLU transferred from the algae to the microbeads as suggested by the higher partition coefficient of micro-PS (Log Kp = 6.6), which confirmed a high affinity of fluoranthene for polystyrene microparticles. However, this did not lead to a modification of fluoranthene bioaccumulation in exposed individuals, suggesting that micro-PS had a minor role in transferring fluoranthene to mussels tissues in comparison with waterborne and foodborne exposures. After depuration, a higher fluoranthene concentration was detected in mussels exposed to micro-PS and fluoranthene, as compared to mussels exposed to fluoranthene alone. This may be related to direct effect of micro-PS on detoxification mechanisms, as suggested by a down regulation of a P-glycoprotein involved in pollutant excretion, but other factors such as an impairment of the filtration activity or presence of remaining beads in the gut cannot be excluded. Micro-PS alone led to an increase in hemocyte mortality and triggered substantial modulation of cellular oxidative balance: increase in reactive oxygen species production in hemocytes and enhancement of anti-oxidant and glutathione-related enzymes in mussel tissues. Highest histopathological damages and levels of anti-oxidant markers were observed in mussels exposed to micro-PS together with fluoranthene. Overall these results suggest that under the experimental conditions of our study micro-PS led to direct toxic effects at tissue, cellular and molecular levels, and modulated fluoranthene kinetics and toxicity in marine mussels.

Interactions of Microplastics with Freshwater Biota

“…Several laboratory studies illustrate the capacity of MPs to modify adverse effects of chemicals by affecting the bioavailability or acting as an additional stressor. For instance, (1) the exposure to spiked MPs lead to an accumulation of pollutants to the tissues of lugworms (PVC, [6]), mussels (PE and PS, [59]), amphipods (PE, [79]), and fish (LDPE, [39]); (2) Besseling et al [80] observed a decreased bioaccumulation of polychlorinated biphenyls in lugworms at higher doses of PS particles; (3) Oliveira et al [40] confirmed a delayed pyreneinduced mortality of juvenile fishes (Pomatoschistus microps) in the presence of PE MPs; and (4) Karami et al [37] as well as Paul-Pont et al [60] detected modulations of adverse effects by an exposure to phenanthrene-loaded LDPE fragments (African catfish) and PS beads and fluoranthene (Mytilus spp. ), respectively.…”

“…As a consequence of particle interaction with tissue or hemolymph cells, marine bivalves can express an immediate stress and immune response. This results in an increased production of reactive oxygen species as well as anti-oxidant and glutathione-related enzymes but also changes the hemocyte phagocytosis activity and the ratio of granulocytes and hyalinocytes [59,60].…”

Comparative Effects of Ingested PVC Micro Particles With and Without Adsorbed Benzo(a)pyrene vs. Spiked Sediments on the Cellular and Sub Cellular Processes of the Benthic Organism Hediste diversicolor

“…After the ingestion, the ingestion processes, dominated shifts in pH, temperature and redox conditions, microplastic particles can potentially release the adsorbed environmental pollutants therefore enhancing both their bioavailability and biological adverse effects to biota. This route of exposure for aquatic organisms, the so called "Trojan horse" effect, remains under-investigated with limited data concerning such phenomena (Syberg et al, 2015;Paul-Pont et al, 2016;Gaspar, 2017).…”

Commentary: Tissue accumulation of microplastics in mice and biomarker responses suggest widespread health risks of exposure

“…In recent years, a good number of studies have indeed demonstrated that microplastics (either pristine or dye-conjugated) exert detectable acute and toxic effects on marine invertebrate and fishes under controlled laboratory settings (see Table 1 for a non-exhaustive summary). Microplastics are taken up and could accumulate in the gills and gut tissues of mussels and oysters (von Moos et al, 2012;Van Cauwenberghe et al, 2015;Paul-Pont et al, 2016;Sussarellu et al, 2016), with histopathology and stress responses documented with the former and reproductive deficiencies noted for the latter, as well as other marine invertebrates (Wright et al, 2013). More recent work has also documented adverse effects of microplastic ingestion in aquatic vertebrates such as the zebrafish (Lu et al, 2016;Chen et al, 2017).…”