Abstract
Within the past decade, microplastic (MP) particles (<5 mm in size) became the focus of both scientific and public attention, on one hand due to their cumulative industrial application and global presence, on the other hand due to their size range allowing the interaction with organisms at the base of the marine food web. Along with the growing evidence of their ubiquitous distribution, the ingestion of MP fibers and fragments has been verified for a variety of marine biota, with fish species being among the group of organisms most intensively studied both in the laboratory and in the field. While the gross of scientific literature focuses on the quantification and chemical characterization of MP in the gastrointestinal tract of fish, in-depth investigations on the impacts or a contextualization of ingestion are rarely accomplished. Yet, the constant media-coverage and omnipresence of the topic present a (threat) scenario among civil society which might lack a solid scientific foundation. This review, therefore, analyses the scientific output of 90 field studies covering 487 different fish taxa with due regard to explanatory variables for MP ingestion. Additionally, it highlights persistent knowledge gaps in relation to the examination of in-situ ingestion effects and proposes measures how to approach them in future research initiatives. Moreover, the potential existence of a publication bias and a consequent distortion of the perception of the topic is evaluated.
Highlights
The History of Field Studies on MP Uptake in FishAmong the diverse anthropogenically caused environmental issues threatening coastal and oceanic ecosystems, plastic litter along with its potential detrimental effects on marine biota has been gaining particular attention and awareness both in the scientific community and civil society (Cunningham and Sigwart, 2019; Völker et al, 2019)
Noteworthy is the gap between the years 1976 and 2010: a review on MP ingestion (Hoss and Settle, 1990) as well as several dietary studies (e.g., Manooch and Hogarth, 1983; Young et al, 1997; Joyce et al, 2002) were published in between those years, their content was not matching the criteria for this review and, not included in this bar chart
Following the categorization applied by Bour et al (2018), the results indicate a significantly lower number of MP particles ingested by filter-feeders in comparison to predators, though the results concerning the frequency of MP-feeders among the different guilds did not differ significantly
Summary
The History of Field Studies on MP Uptake in FishAmong the diverse anthropogenically caused environmental issues threatening coastal and oceanic ecosystems, plastic litter along with its potential detrimental effects on marine biota has been gaining particular attention and awareness both in the scientific community and civil society (Cunningham and Sigwart, 2019; Völker et al, 2019). Published in the same report, the outcomes of the feeding experiments with larval and juvenile fish of different species, which were offered polystyrene and acrylonitrile-butadienestyrene suspension beads, likewise showed no MP uptake, as well as no MP-related mortality or detrimental effects (Colton et al, 1974) Following these early investigations, studies were published that highlighted the facts that the presence of MP in fish guts might be caused by post capture ingestion (Lancraft and Robison, 1980) and that not all fish species and age groups living in MP-contaminated environments are prone to ingest fragments or spherules to a high degree (Hoss and Settle, 1990)
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