In Situ Effects of a Microplastic Mixture on the Community Structure of Benthic Macroinvertebrates in a Freshwater Pond

Abstract

Benthic communities contain some of the most threatened organisms in aquatic habitats due to different anthropogenic pressures. The high abundance of microplastics in sediments will continue to increase in the future, further increasing the probability of interactions between macroinvertebrates and microplastics. In the present study, a benthic community in a relatively pristine shallow pond was exposed either to an environmentally relevant high concentration of a microplastic mixture of 80 g m–2 in the sediment, or a control sediment, without the addition of microplastics. The mixture of microplastics contained irregularly shaped polyethylene, polyvinyl chloride, and polyamide in a ratio of 50:25:25%, respectively. The in situ experiment lasted for 100 d. The total number of taxa that colonized the microcosms was 22 (17 in the control and 18 in the microplastic treatment), and the colonization was not affected by the treatment. The most dominant group within the macroinvertebrate community was the dipteran family Chironomidae, in both the control and the microplastic treatment. No significant differences in the abundance and biomass at a community level were recorded between the groups by permutational multivariate analysis of variance (F = 0.993, p = 0.456 and F = 0.344, p = 0.797, respectively). The mixture of microplastics did not influence the abundance or biomass of the functional feeding groups (F = 1.810, p = 0.137 and F = 0.377, p = 0.736, respectively). The species richness, species abundance, species biomass, Shannon's diversity index, and Simpson's index of diversity showed no statistically significant differences between the control and treatment groups. Czekanowski's quantitative similarity index indicated that 84% of the community remained unaffected after microplastic exposure. Environ Toxicol Chem 2022;41:888–895. © 2021 SETAC

Uptake and Transfer of Polyamide Microplastics in a Freshwater Mesocosm Study

“…Considering these nominal concentrations in the water and the total area of sediment in each replicate mesocosm, amounts of 16.6 g and 166 g PA per m 2 sediment were applied, respectively. The lower concentration was hereby chosen as environmentally relevant [28], while the higher concentration served as the extreme scenario. The application process started in May 2020.…”

“…Direct and indirect effects of stressors across many generations of entire biocenoses can be monitored in these higher tier experiments [26]. Thus far, only very few studies on the effects of microplastic pollution have been conducted in outdoor mesocosms [27,28].…”

Reality Check: Experimental Studies on Microplastics Lack Realism

“…Not only did they use MFs at environmental levels, but they exposed the animals for 71 days, which is time for two reproductive cycles in the species. A recent paper examined in situ effects of high concentrations (80 g m 2 ) of irregularly shaped mixed MPs on freshwater benthic communities, with an exposure of 100 days [58]. However, no effects on abundance, biomass, species richness, Shannon or Simpson measures of community diversity were found.…”

No Effect of Realistic Concentrations of Polyester Microplastic Fibers on Freshwater Zooplankton Communities

“…At the population scale, exposure to microplastics has resulted in reduced Daphnia population biomass (Bosker et al, 2019), microalgae biomass (Green et al, 2016), and population size of calanoid copepods (Heindler et al, 2017). Regarding community-level effects of microplastics, only a limited number of studies have been published to date (Aljaibachi et al, 2020;Marchant et al, 2023;Rauchschwalbe et al, 2022;Silva et al, 2022;Stanković et al, 2022;Yıldız et al, 2022). Similar to the effects of microplastics on individual organisms such as Daphnia, these studies have documented varying effects of microplastics on different communities.…”