Microplastics in Freshwater Sediments Impact the Role of a Main Bioturbator in Ecosystem Functioning

Abstract

While microplastic transport, fate, and effects have been a focus of studies globally, the consequences of their presence on ecosystem functioning have not received the same attention. With increasing evidence of the accumulation of microplastics at sediment−water interfaces there is a need to assess their impacts on ecosystem engineers, also known as bioturbators, which have direct and indirect effects on ecosystem health. This study investigated the impact of microplastics on the bioturbator Tubifex tubifex alongside any effects on the biogeochemical processes at the sediment−water interface. Bioturbators were exposed to four sediment microplastic concentrations: 0, 700, 7000, and 70000 particles kg −1 sediment dry weight. Though no mortality was present, a significant response to oxidative stress was detected in tubificid worms after exposure to medium microplastic concentration (7000 particles kg −1 sediment dry weight). This was accompanied by a reduction in worm bioturbation activities assessed by their ability to rework sediment and to stimulate exchange water fluxes at the sediment−water interface. Consequently, the contributions of tubificid worms on organic matter mineralization and nutrient fluxes were significantly reduced in the presence of microplastics. This study demonstrated that environmentally realistic microplastic concentrations had an impact on biogeochemical processes at the sediment−water interface by reducing the bioturbation activities of tubificid worms.

Revealing the Freezing-Induced Alteration in Microplastic Behavior and Its Implication for the Microplastics Released from Seasonal Ice

“…This alteration in wetting due to freezing could significantly influence the environmental fate of MPs, increasing their mobility and potential ingestion by marine organisms, thus, enter in a food chain. Many studies have demonstrated the toxicity of MPs for benthic fauna, and the MPs in sediment can affect biogeochemical processes by reducing the bioturbation activities of benthic fauna due to their toxic effects. , …”

“…Many studies have demonstrated the toxicity of MPs for benthic fauna, and the MPs in sediment can affect biogeochemical processes by reducing the bioturbation activities of benthic fauna due to their toxic effects. 31,32 The impact of freezing varies with salinity. While freezing in freshwater affects MP behavior, no significant impact on particle size and stability was observed in saline water compared to control groups in our experiment.…”

Optimization of glass separating funnels to facilitate microplastic extraction from sediments

“…Microplastics in sediments pose a threat to the functioning of ecosystems [21] , particularly as they can be ingested by benthic species and therefore ascend to the food chain and enter human diets [ 22 , 23 ]. For this reason, the development of an effective approach for detecting the distribution and concentrations of microplastics in sediments is indispensable for understanding their availability in aquatic systems and, therefore, the threat presented to aquatic animals and related ecological processes.…”

Insights into technical challenges in the field of microplastic pollution through the lens of early career researchers (ECRs) and a proposed pathway forward

“…River sediments are highly variable in their form, necessitating different sampling procedures. They are susceptible to changes in flow and zoogeomorphic processes (Johnson et al, 2020;Wazne et al, 2023) that alter sediment mobility at short (diurnal), long (seasonal), and event-specific (e.g., flooding and drought) time scales (Hurley et al, 2018).…”