Microplastic ingestion alters the expression of some sexually selected traits in a model fish guppy (Poecilia reticulata Peters 1859)

Microplastic contamination in the aquaculture icon Oreochromis mossambicus: Prevalence, characteristics, and comprehensive overview

The global production of plastics has surged to 368 million tonnes annually, leading to significant plastic waste accumulation, projected to reach 12,000 Mt by 2050, impacting aquatic ecosystems. Fish, crucial for their protein and nutrients, are particularly vulnerable to microplastic (MP) ingestion. As a major aquaculture producer and fish consumer, India faces rising plastic pollution in freshwater, which disrupts fish health and growth, posing a significant threat to the sustainability and productivity of aquaculture systems and potential health risks. This study focuses on Mozambique tilapia (Oreochromis mossambicus), valued for its widespread aquaculture use, rapid growth, and nutritional benefits. Our research reveals significant MP contamination (69.23 %) in Mozambique tilapia, with over 80 % from the Ulhas River and 60 % from the Bhima River contaminated and females showing higher susceptibility. These findings emphasise the need for further research on MP impacts on human health and the development of mitigation strategies.

Meta-analysis of the effects of microplastic on fish: Insights into growth, survival, reproduction, oxidative stress, and gut microbiota diversity

Aquatic ecosystems are primary repositories for microplastics (MPs), which pose significant risks to aquatic organisms. This study addresses the gap in understanding the effects of MPs pollution by analyzing 3,757 biological endpoints from 85 laboratory studies. Overall, our results indicate that MPs exposure significantly inhibits fish growth, survival, and reproductive ability, and increases oxidative damage, specifically, MPs exposure leads to elevated levels of malondialdehyde. However, MPs do not have a significant impact on the diversity of fish gut microbiota. Subgroup and correlation analyses indicate that the extent of various toxic effects is influenced by multiple factors, including MPs' type, exposure pathway, size, concentration, as well as the aquatic environment or life stage of the fish. In addition, the regression analysis revealed a relationship between the magnitude of toxic effects and the size, concentration, or duration of MPs exposure. This study provides useful information for understanding the potential impacts of MPs on aquatic organisms and offers new insights for the protection and management of aquatic ecosystems.

A review of the neurobehavioural, physiological, and reproductive toxicity of microplastics in fishes

Microplastics (MPs) have emerged as widespread environmental pollutants, causing significant threats to aquatic ecosystems and organisms. This review examines the toxic effects of MPs on fishes, with a focus on neurobehavioural, physiological, and reproductive impacts, as well as the underlying mechanisms of toxicity. Evidence indicates that MPs induce a range of neurobehavioural abnormalities in fishes, affecting social interactions and cognitive functions. Altered neurotransmitter levels are identified as a key mechanism driving behavioural alterations following MP exposure. Physiological abnormalities in fishes exposed to MPs are also reported, including neurotoxicity, immunotoxicity, and oxidative stress. These physiological disruptions can compromise the individual health of aquatic organisms. Furthermore, reproductive abnormalities linked to MP exposure are discussed, with a particular emphasis on disruptions in endocrine signaling pathways. These disruptions can impair reproductive success in fish species, impacting population numbers. Here we explore the critical role of endocrine disruptions in mediating reproductive effects after exposure to MPs, focusing primarily on the hypothalamic-pituitary-gonadal axis. Our review highlights the urgent need for interdisciplinary research efforts aimed at elucidating the full extent of MP toxicity and its implications for aquatic ecosystems. Lastly, we identify knowledge gaps for future research, including investigations into the transgenerational impacts, if any, of MP exposure and quantifying synergetic/antagonistic effects of MPs with other environmental pollutants. This expanded knowledge regarding the potential risks of MPs to aquatic wildlife is expected to aid policymakers in developing mitigation strategies to protect aquatic species.

Microplastic pollution: a review of techniques to identify microplastics and their threats to the aquatic ecosystem

Microplastics (MPs), small synthetic particles, have emerged as perilous chemical pollutants in aquatic habitats, causing grave concerns about their disruptive effects on ecosystems. The fauna and flora inhabiting these specific environments consume these MPs, unwittingly introducing them into the intricate web of the food chain. In this comprehensive evaluation, the current methods of identifying MPs are amalgamated and their profound impacts on marine and freshwater ecosystems are discussed. There are many potential risks associated with MPs, including the dangers of ingestion and entanglement, as well as internal injuries and digestive obstructions, both marine and freshwater organisms. In this review, the merits and limitations of diverse identification techniques are discussed, including spanning chemical analysis, thermal identification, and spectroscopic imaging such as Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and fluorescent microscopy. Additionally, it discusses the prevalence of MPs, the factors that affect their release into aquatic ecosystems, as well as their plausible impact on various aquatic ecosystems. Considering these disconcerting findings, it is imperative that appropriate measures should be taken to assess the potential risks of MP pollution, protect aquatic life and human health, and foster sustainable development.

Independent and synergistic effects of microplastics and endocrine-disrupting chemicals on the reproductive social behavior of fathead minnows (Pimephales promelas)

Microplastics (MPs) have become an environmental concern in recent years, with most research focused on the physiological effects of exposure. Comparatively little consideration has been given to the potential behavioral impacts of exposure, which may also have fitness consequences for individuals. Moreover, MPs can serve as vectors for endocrine-disrupting chemicals and other locally co-occurring contaminants known to impair behavioral responses. This project aimed to determine whether MPs alone or in association with a common environmental EDC (17-alpha ethinyl estradiol; EE2) alter reproductive behavior and decision-making in fish. Male and female fathead minnows (Pimephales promelas) were exposed to MPs associated with either a low (10 ng/L; MPEE2 10) or high (50 ng/L, MPEE2 50) concentration of EE2, or MPs without EE2 (MPvirgin) for 30 days via a dietary feeding protocol. Behavioral trials were conducted on Day 31 to determine the effects of exposure on male-female social interactions. The expression of male sexually selected traits, including courtship, was unaffected by exposure. However, non-exposed females in all treatment groups trended toward discrimination against exposed males, which reached statistical significance for the MPEE2 50 group. Female fish exposed to MPs, alone or in association with EE2, were equally likely to approach and associate with non-exposed and exposed males. The results from this study suggest that MPs may alter social behavior in fishes and that the behavioral impacts of exposure may be more strongly pronounced in females than males. Such individual-level changes in fitness have the potential to impact population size, with downstream effects on the broader aquatic community.

Microplastic pollution in the gastrointestinal tract of giant river catfish Sperata seenghala (Sykes, 1839) from the Meghna River, Bangladesh

Freshwater rivers are considered the major route for microplastics (MPs), yet limited studies have been reported on MPs in freshwater river fish, especially in Bangladesh. This research reveals the intake of MPs by the giant river catfish Sperata seenghala, collected from the Meghna River, which is the only outlet of the Ganges-Brahmaputra River. Three locations, namely, Chandpur Sadar, Bhola Sadar, and Char Fasson, along the Meghna River, were selected in order to investigate the gastrointestinal tracts (GIT) of the fish. Ninety percent (n=27) of fish (n=30) were contaminated, with fragment-shaped MPs (65%) as the most abundant among the four types. A total of 179 MP particles were detected using micro-Fourier transformed infrared spectroscopy (μ-FTIR), with an average of 5.96 ± 1.32 MP particles per fish. Among the four size groups, the highest proportion of MPs (54%) occurred in the 45-100 μm group; the dominant color among the seven color groups was white (30%). The highest quantity of MPs was found in the relatively densely populated Chandpur Sadar region. Polypropylene-polyethylene copolymer (PP-PE, 23%) was proportionally dominant among the 15 types. No significant relationship was found between the total number of observed MPs and the GIT weight. This study will help us to understand MP pollution in S. seenghala that may transmit to the human body through the food chain.