Unlike many previous studies that typically use unrealistic microplastics like polystyrene microbeads in lab based organismal exposure work, this research focused on microfibers commonly found in marine environments due to textile waste. By exposing oysters to both natural and artificially high microfiber concentrations. The study found that environmentally relevant microfiber levels had significantly fewer physiological effects, emphasizing the importance of using realistic exposure conditions in pollution research.
Here’s some information about the study:
Haskell, H., Suckling, CC., Gomez-Chiarri, M., McMahon, K.W., Preziosi, B., Davies, A.J. (2024). Eastern Oyster (Crassostrea virginica) shows physiological tolerance to polyester microfibers at environmental concentrations. Journal of Experimental Marine Biology and Ecology. 578: 152032
Abstract: Significant research has shown that microplastics are ubiquitous within the marine environment, organisms are interacting with microplastics regularly, and microplastics at high concentrations can have significant impacts on organismal physiology and health. However, the potential impacts of this pervasive pollutant on organismal physiology at environmentally relevant concentrations is less well studied. To this aim, we exposed eastern oysters, Crassostrea virginica to daily doses (45 d total exposure) of polyester microfibers (mean ± 1 SE: length = 662 ± 2 μm; width 16 ± 1 μm, n = 300 fibers, 1.38 g cm-3 density) at environmentally relevant concentrations (0, 2, and 95 fibers L-1) as well as a high exposure concentration (950 fibers L-1) to represent potential future microplastic increases. We quantified physiological responses in five key parameters: somatic growth, survival rate, clearance rate, plastic accumulation in somatic tissues, and cellular energy allocation (CEA). No significant responses were observed in any of these important physiological parameters, suggesting that polyester microfibers at current environmental concentrations appear to pose minimal threat to the physiological well-being of C. virginica within these study conditions. Substantial variation was observed in the number of fibers that accumulated per oyster ranging from 0 to 58 fibers per individual. This relatively broad range of fiber accumulation demonstrates individualistic interactions between oysters and microplastics, highlighting the need for sufficient sample sizes when investigating microplastic accumulation within somatic tissues in order to capture individual variance. Our study also highlights the importance of characterizing microplastic behavior (i.e., suspension time in water) in exposure studies to better understand actual exposure patterns and experimental outcomes. Results from our study demonstrate the critical importance of considering environmental relevance, in terms of exposure concentration, polymer type and particle sinking behavior, when conducting exposure studies and interpreting potential impacts of microplastics on organismal physiology. Our work provides novel information regarding the physiological responses of C. virginica when exposed to environmentally relevant microplastic pollution levels. Such information is beneficial for improving the design of future exposure studies to build upon and vital for understanding the current risk microplastics may pose to marine species and developing management strategies to deal with this emerging pollutant.
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