Quantifying Spatial and Temporal Trends of Microplastic Pollution in Surface Water and in the Eastern Oyster Crassostrea virginica for a Dynamic Florida Estuary

Abstract

Microplastics (MPs) are a ubiquitous pollutant, emphasizing the need to understand their abundance and the factors that influence these patterns around the globe. In a prior study, high numbers of MPs were found in surface waters and tissues of the oyster Crassostrea virginica collected from one location in the Indian River Lagoon (IRL, FL, USA). To better understand spatial and temporal variability of MPs throughout the IRL, for one year, monthly surface water samples were collected from 35 sites, while oysters were collected quarterly from 12 sites. Microscopy and ATR-FTIR were used to quantify MP. In total, 3755 MPs were found in 44% of water samples (mean density ± CI: 1.47 ± 0.09 MP/L). South IRL water had the most MPs, likely associated with proximity to urbanization, inlets (MP sinks) and tributaries (MP sources). MP (n = 3181) were found in 70% of examined C. virginica (n = 1402). Abundances of MP in oysters were lower in the spring and in north IRL. The overall mean abundance was 2.26 ± 0.16 MP/oyster, and the density was 2.43 ± 0.52 MP/g wet tissue weight. Our results provide a more complete picture of MPs in the IRL, a subtropical, shallow-water estuarine system.

Contribution of Stormwater Outfalls to Microplastic Pollution in a Subtropical Estuary Using Data Collected with the Assistance of Citizen Scientists

“…It is interesting that the mean density (0.53 MP/L) was lower than that found by Walters et al [48] of 1.47 ± 0.09 MP/L. This difference may be the result of the collection locations.…”

“…Weather conditions may have also impacted the results, especially fall storms where both projects reported the highest MP densities. Major Hurricane Dorian (Category 5) in September 2019 and multiple tropical storms occurred during the study by Walters et al [48], while Hurricanes Sally (Category 2) in September 2020 and Elsa (Category 1) in July 2021 occurred in Florida during the present study. The month of October had the overall highest number of MPs, followed by September.…”

“…This difference may be the result of the collection locations. Walters et al [48] visited public parks for many collection sites, while the stormwater outfalls and controls were in more remote areas. Weather conditions may have also impacted the results, especially fall storms where both projects reported the highest MP densities.…”

“…The Indian River Lagoon (IRL), located on the east coast of central Florida, is an Estuary of National Significance and generates USD 7.6 billion per year in revenue [55]. A recent year-long study of the IRL by Walters et al [48] found an average of 1.5 MPs/liter of surface water, with 44% of samples containing MPs. Lagoon-wide, 70% of filter-feeding oysters contained MPs with an increase in the more urbanized southern lagoon.…”

Effect of High-Density Polyethylene Microplastics on the Survival and Development of Eastern Oyster (Crassostrea virginica) Larvae

“…A study conducted on edible oysters reported the translocation and accumulation of MPs in the gills, muscles, and digestive glands [ 23 ]. Adult Eastern oysters are sedentary and grow attached to the seabed near the shoreline in intertidal regions, where they are exposed to MPs that are sinking or caught in the biofilm [ 24 ]. A few laboratory studies have been conducted on the impacts of MPs on Pacific oyster ( Crassostrea gigas ) larvae: A previous study found that Pacific oyster larvae can ingest polystyrene particles of less than 20 µm without any significant impact on their development and feeding capacity [ 25 ]; A research conducted on reproductively active Pacific oyster adults and their offspring and reported a decrease in the size and growth of larvae due to polystyrene exposure and a significant decrease in oocyte number and oocyte quality [ 26 ].…”