Effects of microplastics on growth, phenanthrene stress, and lipid accumulation in a diatom, Phaeodactylum tricornutum

The high diversity of Southern Ocean sea stars (Asteroidea) reveals original evolutionary pathways

“…In the present research, virgin polyethylene (PE) microbeads at concentrations up to 1.25 x 10 3 particles / L (or 0.05 mg / L) did not alter the growth of Phaeodactylum tricornutum (Fig.1), suggesting that virgin PE microplastic (MP) have no acute effect on the growth of diatoms at environmentally relevant MP concentrations and size distributions. These results are in line with Gambardella et al (2019) and Guo et al (2020) who found no inhibitory effect on the growth of P. tricornutum exposed to 11 -13 µm and 20 -25 µm PE MP, and 250 µm polyvinyl chloride (PVC) MP at MP concentrations similar to the present work ( up to 7.59 x 10 3 particles / L). Also, Zhang et al (2017) confirmed that exposure to 1,000 µm PVC particles up to 2.73 x 10 3 particles / L did not modify the growth of Skeletonema costatum.…”

“…Few studies have, however, exposed microalgae to environmentally relevant concentrations of MP at longer term (168 -240 h), but still no effect on the growth of microalgae was observed at MP concentrations up to 7.5 x 10 3 particles / L (e.g. Fu et al, 2019;Guo et al, 2020;Lyakurwa, 2017). In a broader context, MP/NP pollution might not affect the population dynamics of a single marine microalgae, but their effects on the composition of larger communities is not well known.…”

“…Studies that showed inhibitory-effects are for example those of Fu et al (2019) and Zhu et al (2019), while growth stimulation after microplastic exposure has been reported by Guo et al (2020). Each of these studies increase our knowledge into the possible effects of microplastic on primary producers, which is currently limited compared to other trophic levels.…”

Micro- and Nanoplastic Exposure Effects in Microalgae: A Meta-Analysis of Standard Growth Inhibition Tests

“…For example, Su et al (2019) observed an increase of cell density over a 10-d period, with a concomitant reduction in the cell size suggestive of nitrogen limitation (Kilham et al, 1997). Also, no growth inhibition has been reported after a 4-d exposure but a significant inhibition and lipid accumulation after 9-d, which could be explained by nutrient depletion due to algal growth but also sorption to the polymers (Guo et al, 2020). Therefore, time-related changes in the growth conditions may mask true response to the exposure, and the OECD-recommended duration of 72-96 h for the algal growth inhibition test design must be followed.…”

“…However, in some cases, PVC induced less inhibition at higher concentrations (≥100 mg/L) compared to 10 mg/L (Fu et al, 2019). Moreover, for unplasticized PVC, Guo and co-workers showed growth stimulation at 50 g/L compared to significant inhibition (37%) at 0.05 mg/L (Guo et al, 2020). The main reason for these counter-intuitive observations could be a reduced exposure during the test because of the uncontrolled particle aggregation and settling, which are enhanced at higher concentrations.…”