Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Sep 10:786:147534.
doi: 10.1016/j.scitotenv.2021.147534. Epub 2021 May 6.

Detection of SARS-CoV-2 RNA in bivalve mollusks and marine sediments

David Polo  1 , Marta Lois  2 , María Teresa Fernández-Núñez  3 , Jesús L Romalde  4
Affiliations

Detection of SARS-CoV-2 RNA in bivalve mollusks and marine sediments

David Polo et al. Sci Total Environ. .

Abstract

The presence of SARS-CoV-2 in wastewater pose the question of whether this new pandemic virus could be released into watercourses and potentially continue to finally reach coastal waters. In this study, we employed two bivalve molluscan species from the genus Ruditapes as sentinel organisms to investigate the presence of SARS-CoV-2 signals in the marine coastal environment. Estuarine sediments from the natural clam banks were also analyzed. Viral RNA was detected by RT-qPCR, targeting IP4, E and N1 genomic regions. Positive samples were also subjected to a PMAxx-triton viability RT-qPCR assay in order to discriminate between intact and altered capsids, obtaining indirect information about the viability of the virus. SARS-CoV-2 RNA traces were detected in 9/12 clam samples by RT-qPCR, from which 4 were positive for two different target regions. Viral quantification ranged from <LoQ to 4.48 Log genomic copies/g of digestive tissue. Regarding the sediment samples, 3/12 were positive by RT-qPCR, but only IP4 region was successfully amplificated. Quantification values for sediment samples ranged from <LoQ to 3.60 Log genomic copies/g of sediment. RNA signals disappeared in the PMAxx-triton viability RT-qPCR assay, indicating non-infectious potential. In addition, the recently discovered human-specific gut associated bacteriophage crAssphage was also quantified as a biomarker for the presence of human-derived wastewater contamination on the study area. CrAssphage was detected in 100% of both types of samples with quantification values ranging from <LoQ to 5.94 Log gc/g digestive tissue and from <LoQ to 4.71 Log gc/g sediment. Statistical analysis also showed that quantification levels for the crAssphage in clams are significantly higher than in sediments. These findings represent the first detection of SARS-CoV-2 RNA in the marine environment, demonstrating that it can reach these habitats and make contact with the marine life.

Keywords: Bivalve mollusks; COVID-19; Marine environment; SARS-CoV-2; Sediments; Wastewater.

PubMed Disclaimer

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Unlabelled Image
Graphical abstract
Fig. 1
Fig. 1
Map of the estuaries and river catchment in Galicia (NW of Spain) showing the clam banks 1 (B1) and 2 (B2) (red squares), and sampling points (SP1 and SP2). Locations for wastewater treatment plants (WWTP), sewage pump station (SWPS) and non-treated sewage outfalls (SW), a camping area (white triangle) and an urbanization (white square) are indicated. During the summer, there is a significant increase of the population in the area surrounding bank 1 due to tourism. Municipality where the outbreak was reported is marked in yellow. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 2
Fig. 2
Boxplot diagrams showing crAssphage quantification in clams and sediment samples in the natural clam bank 1 (B1) and 2 (B2). Results are expressed as Log copies of genome (cg)/g of digestive tissue (DT) or sediment (Sed).
See this image and copyright information in PMC

References

    1. Aguiló-Gisbert J., Padilla-Blanco M., Lizana V., Maiques E., Muñoz Baquero M., Chillida-Martínez E., Cardells J., Rubio-Guerri C. 2021. First Description of Natural SARS-CoV-2 Infection in Two Wild American Minks (Neovison vison). Preprints 2021. - DOI - PMC - PubMed
    1. Ahmed W., Angel N., Edson J., Bibby K., Bivins A., O’Brien J.W., Choi P.M., Kitajima M., Simpson S.L., Li J., Tscharke B., Verhagen R., Smith W., Zaugg J., Dierens L., Hugenholtz P., Thomas K.V., Mueller J.F. First confirmed detection of SARS-CoV-2 in untreated wastewater in Australia: a proof of concept for the wastewater surveillance of COVID-19 in the community. Sci. Total Environ. 2020;728 doi: 10.1016/j.scitotenv.2020.138764. - DOI - PMC - PubMed
    1. Beyer J., Green N.W., Brooks S., Allan I.J., Ruus A., Gomes T., Bråte I., Schøyen M. Blue mussels (Mytilus edulis spp.) as sentinel organisms in coastal pollution monitoring: a review. Mar. Environ. Res. 2017;130:338–365. doi: 10.1016/j.marenvres.2017.07.024. - DOI - PubMed
    1. Bivins A., Greaves J., Fischer R., Yinda K.C., Ahmed W., Kitajima M., Munster V.J., Bibby K. Persistence of SARS-CoV-2 in water and wastewater. Environ. Sci. Technol. Lett. 2020;7, 12:937–942. doi: 10.1021/acs.estlett.0c00730. - DOI - PMC - PubMed
    1. Butler D., Davies J.W. In: Urban Drainage. Butler D., Davies J.W., editors. Spon Press, Taylor and Francis Group; New York, USA: 2004. Combined sewers and combined sewer overflows; pp. 254–289.