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Using a Metabarcoding Approach to Evaluate the Impacts of Nanoplastics on Benthic Meiofauna and Eukaryotic Microbial Communities
Citation:
Giroux, M., J. Reichman, T. Langknecht, R. Burgess, AND K. Ho. Using a Metabarcoding Approach to Evaluate the Impacts of Nanoplastics on Benthic Meiofauna and Eukaryotic Microbial Communities. 2020 SETAC North America Annual Meeting, Virtual, November 15 - 19, 2020.
Impact/Purpose:
Plastics enter the environment and degrade into small nanoplastic particles where the effects of these particles on communities of marine organisms is unknown. This research used genetic tools (DNA metabarcoding) to understand how nanoplastics can disrupt entire organism communities present on marine sediment. This project will provide valuable information to the agency for potential regulation of nanoplastic materials as well as provide the scientific community some of the first information on the effects of nanoplastic particles on population and community-level endpoints.
Description:
As the abundance of plastic increases in marine systems, the adverse biological and ecological effects of plastics of various size classes (macro, micro, nano) need to be evaluated to address potential risks. Nanoplastic particles (NPs) are of growing concern and enter marine systems primarily through fragmentation of larger plastics present in the environment. Marine sediments act as a sink for many contaminants, including nanoplastics, and are rich habitats for benthic meiofauna and other eukaryotic communities which form the base of the marine food web and presumably interact with nanoplastics. However, little is known about the effects of nanoplastics on individual species, community diversity, or ecosystem structure. Conventional morphological identification of benthic organisms is often a time-consuming process, but molecular methods such as metabarcoding utilize high-throughput sequencing to assess community diversity and structure from environmental DNA/RNA. Therefore, the objective of this study is to use an RNA metabarcoding approach to investigate the effects of nanoplastics on benthic meiofaunal and eukaryotic microbial community diversity. Sediment cores (mesocosms) were collected from the Narrow River estuary in Rhode Island (USA) and exposed to 900nm polystyrene beads at concentrations of 0, 0.1, 1, 10, or 100 mg/kg dry weight in sediment for two weeks. Following exposure, RNA and DNA were extracted from the top sediment layer, RNA was reverse-transcribed, 18S and CO1 genes were PCR-amplified, and then amplicons were sequenced on an Illumina platform. Preliminary results indicate that α-diversity observed-OTUs and Faith’s-PD were significantly increased in the 100 mg/kg treatment. Likewise, there were dose-dependent effects of nanoplastics on β-diversity Jaccard and Unweighted-Unifrac distances. The value of using RNA as a genetic template to achieve a more accurate representation of communities was evaluated. To our knowledge, this is the first demonstration of a dose-response relationship for NP particles at a community level, and it continues to show the utility of using community endpoints to assess the impacts of nanomaterials.
