Impacts of Micro- and Nano-Sized Plastic Particles on Benthic Invertebrates: A Literature Review and Gap Analysis

Abstract

As documented by the numerous publications that have appeared in recent years, plastic pollution of the environment and the effects on the respective ecosystems are currently one of the most intensely discussed issues in environmental science and in society at large. Of special concern are the effects of micro-and nano-sized plastics. A key issue in understanding the fate and potential effects of micro-and nano-sized plastics is their dynamic nature, as the size, shape, and charge of the particles change over time. Moreover, due to various biological processes, such as the aggregation of organic material and/or bacteria ("biofouling"), the density of plastic particles that settle in the sediments of aquatic ecosystems may be several orders of magnitudes higher than that in the surrounding waters. Consequently, the risk posed by plastic pollution to benthic fauna is considerably high. Nonetheless, the vast majority of studies examining the effects of microplastics have focused on pelagic organisms so far. We therefore conducted a comprehensive literature review to examine the impact of micro-and nano-sized plastics on benthic invertebrates, including the physical and chemical effects of leaching and the interactions of plastic particles with contaminants. Overall, 330 papers were reviewed for their fulfillment of different criteria (e.g., test species, plastic material, particle shape, particle size, exposure concentration, exposure route, assay type, assay duration), with 49 publications finally included in our survey. A comprehensive gap-analysis on the effects of plastic particles on benthic invertebrates revealed a wide variety of effects triggered by micro-and/or nano-sized plastics but also distinct differences regarding the plastic materials tested, the size fractions applied, the shape of the respective particles, and the exposure routes tested. Our review concludes with a discussion of the important research gaps concerning freshwater ecosystems and recommendations for future areas of research.

Microplastic Contamination in Freshwater Environments: A Review, Focusing on Interactions with Sediments and Benthic Organisms

“…Plastics with higher density than water are expected to sink, but some studies have shown that low-density polymers are also deposited on the substrates of aquatic basins due to biofouling by bacteria, algae, and other organisms [61]. Due to biological processes the density of microplastics in sediments may be several orders of magnitudes higher than that in surroundings water [62]. MPs in Rivers, A Major Route for MP Transport…”

“…As observed above, studies examining the ecotoxicological effect of MPs are still mostly focused on pelagic organisms, while knowledge on toxic effects on benthic organisms is still limited [62]. It can be seen by the articles published since 2010 for all the scientific journals indexed in Scopus that in total 44 studies have been published concerning the impacts of plastic particles on benthic organisms, with the majority on benthic marine organisms and only 10 on freshwater benthos.…”

Microplastics Effects on Reproduction and Body Length of the Soil-Dwelling Nematode Caenorhabditis elegans

“…The design of more realistic experimental setups with soils is challenging because currently there are only few data on MP contamination in soils and it is not clear whether the MP concentrations found to date in urban (0.3-67.5 g kg −1 ), riparian (0-0.055 g kg −1 ), and agricultural soils (0-42,960 particles kg −1 ) (Helmberger et al, 2019) lead to negative effects on soil biota. Due to detection limits, even less data is available in environmental samples for MP particles <10 µm (Haegerbaeumer et al, 2019) and thus for the ingestible size range of C. elegans. Given the aliquot of 100 µl that we gave to each nematode in our experiments, one nematode was effectively exposed to 0.1, 1, and 10 µg of MP.…”

Perspectives and challenges of micro/nanoplastics‐induced toxicity with special reference to phytotoxicity

“…Usually plastic fragments measuring up to a size of 100 nm are considered as nanoplastics (NPs); while, plastic fragments ranging between 100 and <5 mm are considered as MPs (Haegerbaeumer, Mueller, Fueser, & Traunspurger, 2019; Koelmans, Besseling, & Shim, 2015a; Moore, 2008). The environmental source of micro/nanoplastics (M/NP) may be primary (from manufactured products) or secondary (transformation of large plastics into small fragments; Maity, Chatterjee, Guchhait, De, & Pramanick, 2019).…”