Microplastic prevalence in two fish species in two U.S. reservoirs

Abstract

The emergence of microplastics as a potential contaminant requires understanding the distribution and potential consumption of microplastics across ecosystems and species. Freshwater environments are known to have high concentrations of microplastics, but very little is known about the concentrations of microplastics within lacustrine fish. The very high prevalence and numbers of microplastics in two fish species in agricultural reservoirs in this study indicates that lacustrine fish may be at high risk of microplastic contamination. AbstractMicroplastics in the environment can impact feeding and physiological functions of organisms. Most studies have focused on marine systems, and studies of lacustrine organisms are less common. We examined microplastic concentration in 72 gizzard shad and 24 largemouth bass from two agricultural reservoirs in the midwestern U.S.A. with differing shoreline development. Microplastics were found in 100% of the fish, with 1-49 No. Fish −1 , independent of shoreline development. Bass had higher concentrations overall than shad. For bass, microplastics were more concentrated in the guts rather than gills, but the opposite was the case for shad, suggesting that feeding guild may influence where microplastics accumulate in fishes. The prevalence and concentrations reported here are greater than reported in marine systems and higher than reported in riverine studies. Our results underscore the ubiquitous distribution of microplastics and suggest that lake ecosystems in agricultural landscapes may be particularly susceptible to microplastic contamination.

Microplastics in freshwater fishes: Occurrence, impacts and future perspectives

“…Consequently, there remains a lack of knowledge over whether benthic fishes, which often tend to ingest more MPs than pelagic feeders within the same environment (McGoran et al, 2017(McGoran et al, , 2018McNeish et al, 2018), are similarly disproportionally impacted by MP exposure. Trophic transfer studies could additionally determine if MP transfer efficiencies are similar from prey to predatory fish as between invertebrates and fish, which might explain different MP ingestion patterns in wild fish occupying different niches and trophic levels (Campbell et al, 2017;Hurt et al, 2020;McNeish et al, 2018;Roch et al, 2019).…”

Microplastics in Food: A Review on Analytical Methods and Challenges

“…Biological matrices were digested and removed from fish samples using various pretreatment methods. For large fish, the stomach and/or gastrointestinal tract (GIT) was isolated and digested to detect microplastics [ 9 , 25 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 60 , 61 , 62 , 63 , 65 , 66 , 67 , 68 , 69 , 70 , 72 , 73 , 74 , 75 ]. Unlike the digestion method used for sea salts, various chemicals were used to decompose organic materials, including potassium hydroxide (KOH) [ 9 , 22 , 23 , 38 , 45 , 47 , 48 , 53 , 55 , 56 , 58 , 62 , 64 , 71 , …”

“…Raman spectroscopy was also applied [ 59 , 62 ] due to its enhanced performance with smaller particles [ 100 ]. Visual inspection under a microscope with or without staining was less popular, most likely because of the complexity of the sample matrices and the potential for false-positive identification [ 43 , 49 , 60 , 63 , 65 , 66 , 67 , 68 , 72 ]. Further, scanning electron microscopy (SEM) was used to identify smaller microplastic particles [ 22 , 38 ].…”

“…Microplastics were rarely found in edible tissues, such as muscle [ 9 , 22 , 59 , 64 , 71 ], but they were predominantly found in digestive tracts [ 9 , 22 , 23 , 25 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 60 , 61 , 62 , 63 , 65 , 66 , 67 , 68 , 69 , 70 , 72 , 73 , 74 , 75 ]. Because it is unclear how microplastics are transported to edible tissues, human exposure to microplastics due to the consumption of edible fish tissue requires further evaluation.…”

“…Gill tissue has been found to be another important entry point for microplastics in fish [ 9 , 69 , 72 ]. Although microplastics from the water can accumulate in gill tissue during ventilation, it is unlikely that microplastics are introduced into the circulatory system since they were not identified in soft and edible tissues of the same fish [ 9 ].…”