The Effect of Microplastics on Oysters

The study also confirmed that estuaries have higher concentrations of microplastics than their riverine inputs, a finding uncovered in other studies as well. Given that the river is continually flushed of plastics, this is not surprising, because the estuary acts as a sink for these plastics, which, over time, degrade to form microplastics.

Research Methods

The microplastics particles that we are analyzing are often so small that they are invisible to the human eye. The number of microplastics actually increases with decreasing size, which calls for sophisticated analytical instrumentation and a robust research approach.

To analyze the abundance of microplastics in these oyster reefs and understand their potential threat, we used three key research methods: “the single one-pot” method for sample preparation, Nile red fluorescence to quantify the collected microplastics samples, and LDIR analysis to identify the major types of plastics in the collected samples. The “single one-pot method” is a novel approach developed by our lab that involves utilizing inexpensive jars, such as mason jars, to collect and prepare water samples for analyses. The advantage of this method is that it minimizes contamination and sample loss, because the sample is processed in the same jar in which it is collected, and the process successfully isolates microplastics needed for analyses.

These microplastic samples were then quantified using Nile red fluorescence detection. Adding a few drops of Nile red dye onto filters with microplastics reveals the exact quantity of microplastics within the samples. To identify the key types and size fractions of plastics in the collected samples, Agilent’s 8700 system was used. This instrument is the first major application of LDIR analyses to determine, characterize, and identify microplastics in natural waters.

A combination of the instrument’s proprietary quantum cascade laser (QCL) with a single-point mercury cadmium telluride (MCT) detector and rapid scanning optics allowed for two effective modes of action. By actioning these techniques, particles are located in the first step, and then information on the size and shape of particles can be obtained. In the second step, a full spectrum is acquired for each particle, while the surrounding areas are ignored. This information is then compared to a spectral database built into the software in a fraction of the time needed with a traditional FTIR system.

The Critical Nature of This Research

Due to mass plastic production, there is now an extensive and increasing amount of microplastics in our environment, and scientific research has not yet uncovered an effective method to entirely remove these particles. Because this is a relatively new threat to the environment, further research needs to take place to understand the true impact of these pollutants, but one thing we do know is that these contaminants do not belong in our environment at all, and certainly not on such a large scale.

Existing research already supports the fact that plastic contaminants pose a threat to aquatic organisms, and it’s very possible that these plastic particles also pose a threat to our own health given the rate that they are entering our environment and our food chain. The research we are conducting at the University of Mississippi is essential to filling in blanks on a known threat to our ecosystem. There is hope that this research could go on to inspire further needed research on the topic and inform our understanding of the exact nature of this threat to human and animal health.

Such research has the potential to guide policymakers in developing needed strategies to control and mitigate this environmental threat and provide evidence to regulate the use of our plastic.

One caveat, however, is that different labs around the world performing microplastics research adopt different testing approaches. These variations may hinder the accurate determination of the fate of microplastics and its global distribution across our oceans. Therefore, global harmonization and standardization of monitored microplastics testing methods is essential if we are to transform this investigative research into routine environmental screening procedures.