Abundance and properties of microplastics found in commercial fish meal and cultured common carp (Cyprinus carpio)

Abstract

Microplastics (MPs) are environmental contaminants that are of increasing global concern. This study investigated presence of MPs in four varieties of marine derived commercial fish meal, followed by identification of their polymer composition using Fourier-Transform Infrared (FTIR) spectroscopy. Exposure experiments were conducted on cultured common carp (Cyprinus carpio) by feeding four varieties of commercially available fish meal to determine relationships between abundance and properties of MPs found both in meal and those transferred to cultured common carp. Mean particle sizes were 452±161 μm (±SD). Fragments were the predominant shape of MP found in fish meal (67%) and C. carpio gastrointestinal tract and gills (65%), and polypropylene and polystyrene were the most present plastic polymers found in fish meal (45% and 24%, respectively) and C. carpio (37% and 33%, respectively). Positive relationships were found between MP levels in fish meal and C. carpio. This study highlights that marine derived fish meal may be a source of MPs which can be transferred to cultured fish, thus posing a concern for aquaculture.

Microplastics in fish and fishmeal: an emerging environmental challenge?

“…Our review has shown that potassium hydroxide digestions are regularly used for microplastic extractions from gastrointestinal fish tissues. KOH has also been used for fishmeal digestions 39 , 40 , but recovering microplastics < 150 µm does not seem possible for fishmeal with this method. The investigation of small microplastics is important, but previously often neglected.…”

Microplastic contamination caused by different rearing modes of Asian swamp eel ( Monopterus albus )

“…Our study showed that microplastic abundances (1.2–4.7 items/individual or 0.009–0.03 items/g) in eels were relatively low compared with other aquatic products reared by human, such as Cyprinus carpio (>10 items/individual; Hanachi et al., 2019), Crassostrea gigas (0.62 items/g; Teng et al., 2019), Mugil cephalus (0.2–4.3 items/individual; Cheung, Lui, & Fok, 2018) and Mytilus galloprovincialis (4.4–11.4 items/g; Renzi et al., 2018). Moreover, the microplastics were prevalent in the guts of eels, but their abundances were especially high in the foregut.…”

“…These results indicate that fish diets might be a major source of microplastic contamination in circulating‐water farming system. Microplastics were recently reported in fish diets (Hanachi et al., 2019). In this study, fish diets came from mixed fish species materials in local fishery markets.…”

“…Many studies have demonstrated the occurrence of microplastics in commercially wild‐caught fish and shellfish species (Faggio, Tsarpali, & Dailianis, 2018; Fang et al., 2019; Prokić, Radovanović, Gavrić, & Faggio, 2019; Su et al., 2019; Yuan, Liu, et al, 2019; Yuan, Lv, et al, 2019). In stark contrast, however, our knowledge of microplastics as ingested by rearing aquatic products, especially freshwater species, remains surprisingly limited (Hanachi, Karbalaei, Walker, Cole, & Hosseini, 2019).…”

“…During eel rearing, a fair amount of plastic products are used in the process of eel farming, such as nylon cages and polyethylene films, which may cause microplastic contamination in aquaculture ponds used to rear animals. Furthermore, farmed eels are usually fed diets consisting of fish material that may already be contaminated with microplastics (Hanachi et al., 2019).…”