Microplastics and freshwater microalgae: what do we know so far?

Abstract

The constant entry of microplastics in several environmental matrices has been of great concern to the scientific community and to society in general, mainly due to the mysteries that surround the implications of this pollutant in the environment. Freshwater ecosystems are resources especially susceptible to variations in environmental quality, and the lack of data on the impacts caused by plastic fragments exacerbates the vulnerability of this environment. Considering the results of other studies, which demonstrate the increasing entry of polymeric fragments in the aquatic environment can lead to algae growth inhibition, an investigation was carried out to determine the current state of research on the interaction between microplastics and freshwater microalgae. In total, 20 scientific articles were analyzed. Different species were subjected to toxicological tests under controlled conditions in the laboratory with small microplastics (size range between 0.1 and 1000 lm), primary and secondary microplastics of different types of polymer. Four toxicity class of indicators were chosen to assess the microalgae response to exposure to microplastic in the selected studies: growth inhibition; photosynthetic activity; pigment analysis; and enzymatic activity and oxidative stress. In this review, a critical analysis is made on the effects of the shape, size, concentration, and duration of exposure to microplastics and research gaps are identified to guide future research priorities in this area of study.

Effects of leachates from UV-weathered microplastic on the microalgae Scenedesmus vacuolatus

“…Adverse effects of microplastics towards microalgae may either stem directly from the physical presence of particles or by the secondary effects from leaching chemicals [ 3 , 4 ]; however, these are difficult to distinguish due to their frequent co-occurrence. The first process may lead to particle adsorption, aggregation, loss of membrane integrity, or shading effects as discussed in previous studies [ 2 , 5 , 6 ]. In contrast, the second process of indirect effects induced by chemicals leaching from microplastics has gained little attention for microalgae so far, despite many algae being able to colonize on plastic surfaces [ 7 , 8 ].…”

Combined effects of P25 TiO2 nanoparticles and disposable face mask leachate on microalgae Scenedesmus obliquus: analysing the effects of heavy metals

“…32 The previous ndings corroborated the toxicity results presented here, showing that microplastics reduce growth rates regardless of size, concentration, or type. 33,34 Based on the ndings of this study, it is possible to hypothesize the mechanism by which nTiO 2 is toxic to Scenedesmus obliquus. Previous studies on nTiO 2 toxicity towards Scenedesmus obliquus also showed similar results.…”

Effects of Polystyrene Microplastics on Growth and Toxin Production of Alexandrium pacificum

“…In addition to Chl a, a variety of photosynthetic pigments such as Chl b and carotenoids also exist on chloroplast membrane, all of which are involved in absorbing light energy for photosynthesis [17,42]. The contents of these photosynthetic pigments in microalgae may be affected by MP [43], such as Chl b and carotenoids were more sensitive to polystyrene MP than Chl a in freshwater microalgae Euglena gracilis [17]. Moreover, the strain of A. pacificum ATHK is a PST-producing dinoflagellate, and the increase in Chl a content may also be related to PST biosynthesis in microalgal cells.…”

“…The extraction of PST from microalgal cells was according to our previous study [43]. In brief, 50 mL of microalgal cultures were centrifuged at 6000× g for 10 min to remove the supernatant, then pellets of microalgae were suspended in 2 mL of 0.1 mol L −1 acetic acid and vortex mixed for 1 min.…”