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Effects of Polystyrene Nanoplastic on Benthic Microbial Communities
Citation:
Giroux, M., J. Reichman, T. Langknecht, B. Smith, R. Burgess, AND K. Ho. Effects of Polystyrene Nanoplastic on Benthic Microbial Communities. SETAC North Atlantic Chapter, 28th Annual Meeting 2022, Groton, CT, June 27 - 28, 2022.
Impact/Purpose:
This project will provide valuable information to the agency for potential regulation of nanoplastic materials, and provide the scientific community some of the first information on the adverse effects of nanoplastic particles on microbial communities that contribute to ecosystem maintenance. Additionally, this information is valuable to the public because it demonstrates that plastic particles may directly interact with microbes in the environment.
Description:
Plastic particles are found in aquatic systems worldwide, and the effects of plastics on ecosystem health are of growing concern. Macro- and microplastics fragment into nanoplastic particles (<1 µm) in the environment, often accumulating in sediments. Marine sediments act as a sink for many contaminants including plastic particles and are also rich habitats for microbial communities. Microbes are vital for ecosystem maintenance as foundational components of food webs and contributing to biogeochemical processes such as carbon and nutrient cycling. However, some contaminants adversely affect microbial communities and indirectly alter environmental conditions, thus changing the balance of microbial communities. Macro- and microplastics can be substrates for microbial growth, but less is known about the interaction of nanoplastics and microbes. Environmental DNA metabarcoding allows for rapid and comprehensive detection of microbial communities via high-throughput sequencing to assess community structure and function. The objective of this study was to use a 16S rRNA metabarcoding approach to investigate the effects of polystyrene nanoparticles on microbial community diversity and structure. Mesocosms were collected from the Narrow River estuary in Rhode Island (USA) and exposed to seawater-weathered 900 nm diameter nanoplastic spheres at concentrations of 0, 0.1, 1, 10, or 100 mg/kg dry weight amended to a reference sediment for two weeks. Following exposure, DNA was extracted from the top 1 cm sediment layer, 16S rRNA gene marker was PCR-amplified, and amplicons were sequenced on an Illumina MiSeq. A dose-dependent decreasing trend in α-diversity was observed. Additionally, the abundance of anaerobic, sulfur-reducing bacteria increased in higher NP treatments compared to lower treatments. This showcases a change in microbial community structure in response to increasing NP exposure, possibly due to polystyrene as a new source of organic-based material within the mesocosms. These results, and the findings of previous studies evaluating nanoplastic impacts to eukaryotic communities (i.e., meiobenthos), contribute to the understanding of plastic particles directly and indirectly affecting environmental conditions leading to community-level impacts.
