A Biomarker Approach as Responses of Bioindicator Commercial Fish Species to Microplastic Ingestion: Assessing Tissue and Biochemical Relationships

Microplastic filtering and its physiological effects on the Mediterranean bath sponge Spongia officinalis (Porifera, Demospongiae)

Microplastics (MPs) pose an increasing and significant threat to marine biodiversity and there is a current need to determine the effects of exposure on benthic sessile invertebrates. This study examines the filtration capacity and retention of MP particles, as well as their physiological impacts in the marine sponge Spongia officinalis, a bioindicator species. The findings revealed a very high filtration capacity for MPs within the size range of 1-5 μm, along with a rapid turnover rate, as a large portion of particles were expelled within 48 h of exposure. Histological analyses detected MP particles within the cellular structures of the analyzed tissues, indicating that MPs of this size can penetrate cellular barriers. In terms of physiological effects, detoxification activity was activated during the depuration phase, and lipid peroxidation was observed during both the exposure and depuration phases. Overall, this study provides critical insights into the filtration and retention capacity, intercellular integration of MP particles, and the physiological effects of MP exposure in S. officinalis, providing a baseline for future research.

Microplastic contamination and biological alterations in Atlantic wild fish populations, and human health risks associated to fillet consumption

This study tested the hypothesis that long-term exposure to microplastics (MPs) is causing biological alterations in North Atlantic wild populations of Trisopterus luscus (pouting) and Merluccius merluccius (hake). It also estimated the human risk of MP intake (HRI) through fillet consumption, and combined the HRI and polymer health hazard in the Risk of Intake and Polymer Hazard Index (RIPHI). Fish (103) were analysed for MPs (gastrointestinal tract, gills, liver, brain, muscle), biomarkers (physical condition, neurotoxicity, energy production, oxidative stress and damage) and general stress (Integrated Biomarker Response - IBR). After particle analysis (Fourier Transform Infrared spectroscopy, Raman spectroscopy) and data correction for contamination, MPs accounted for 77 % of 311 particles. From 103 fish, 79 % contained MPs. The overall mean concentration ±SD was 0.09 ± 0.09 MP g-1 (2.32 ± 2.35 MPs ind-1) with no significant interspecific differences (p > 0.05). Among body sites, brain had the highest MP concentration (pouting: 0.6 MP g-1; hake: 0.5 MP g-1). Most abundant polymers were polyethylene (40 %), polypropylene (21 %) and polymethyl methacrylate (12 %). Fragments (<150 μm) predominated. MP profiles pointed to prey-predator transfer. Fish with MPs had higher stress levels (IBR, pouting: 0.317; hake: 0.200) than specimens without MPs (pouting: 0.0; hake: 0.062). Oxidative stress was the effect most clearly linked to MPs. Hake fillet poses lower HRI (e.g., 0.2 to 1.5 MPs day-1) than pouting fillet (e.g., 0.4 to 3.0 MPs day-1). RIPHI values showed the opposite trend (e.g., hake: 138 to 1038; pouting: 113 to 845), indicating medium to high risk to human consumers. Findings related long-term MPs exposure in the natural habitat with biological alterations in wild fish populations, highlight the importance of food diversification for a healthy alimentation, and stress the urgent need of reducing MPs pollution to promote ecosystem sustainability and global health.

Individual and combined effects of microplastics and diphenyl phthalate as plastic additives on male goldfish: A biochemical and physiological investigation

The development of the plastics industry worldwide has led to an increase in the rate of plastic waste and chemical additives such as microplastics (MPs) and diphenyl phthalate (DPP) in the environment. The penetration of these pollutants into aquatic ecosystems has also raised concerns about their toxic effects, individually and in combination. The present study investigated the individual and combined toxicity of MPs and DPP on the health of male goldfish. A 28-day exposure experiment was conducted using different concentrations of DPP (2.5, 5.0, 7.5 μL L-1) and MPs (20, 40 mg L-1), both individually and in combination. Biochemical markers, enzyme activities, and hormone levels were evaluated to ascertain the effects on metabolic, renal, and reproductive health. The findings revealed that concurrent exposure to DPP and MPs markedly elevated plasma glucose, creatinine, triglycerides, and cholesterol levels, accompanied by notable reductions in high-density lipoprotein and low-density lipoprotein. Moreover, combined exposures resulted in liver damage, as evidenced by elevated serum glutamic-oxaloacetic transaminase, serum glutamic-pyruvic transaminase, alkaline phosphatase, lactate dehydrogenase, and gamma-glutamyl transferase activities and disruptions in protein synthesis and immune response, with notable decreases in total protein, albumin, and globulin. Testosterone levels decreased, while estradiol levels increased, indicating endocrine disruption and potential reproductive impairment. These findings indicated the adverse synergistic effects of MPs and DPP on the physiology of goldfish. Therefore, further research must be conducted to increase our knowledge of their ecotoxicological risks.

Floating microplastics along the western Mediterranean Sea: Are we reaching a "Good Environmental Status" or drifting away?

This study investigates the spatial and temporal distribution of sea surface microplastic in the Spanish Mediterranean Sea, assessing compliance with the Good Environmental Status (GES) criteria of the European Marine Strategy Framework Directive 2008/56/EC and Barcelona Convention. Data from 668 sea surface water samples collected from 2017 to 2023 were analysed to classify their status according to indicators of microplastic pollution. A mean abundance of 0.24 ± 1.80 items/m2 of sea surface microplastics was quantified, with significant differences between locations, zones, areas, and macro-areas (KW, p <0.05). The highest abundance was observed in the protected area of the Columbretes Islands (14.26 ± 8.66 items/m2) and the lowest in Fuengirola (0.0008 ± ND items/m2). The peninsular coast showed a higher abundance of microplastic (0.41 ± 0.27 items/m2) than the Balearic Islands (0.21 ± 0.06 items/m2). Fragments and sheets accounted for 72 % and 15 % of the microplastics, respectively. The highest microplastic abundance was observed in 2017 (0.85 ± 0.5 items/m2) and the lowest in 2022 (0.07 ± 0.01 items/m2), but no temporal trend was detected (MK, p >0.05). According to GES, 98 % of the stations were classified as having "Moderate" to "Very poor" conditions, while only 2 % were in good or high environmental status. This study confirms the lack of GES achievement along the Spanish western Mediterranean coastal waters and highlights the need for action to reduce plastic waste and prevent marine pollution.

Relations between microplastic contamination and stress biomarkers under two seasonal conditions in wild carps, mullets and flounders

Potential effects of microplastics (MP, plastic particles <5 mm) on the levels of multiple stress biomarkers were investigated in wild fish populations of Cyprinus carpio, Mugil cephalus, Platichthys flesus captured in the Minho River estuary located in the Iberian Peninsula. Specimens were collected in March and September 2018, corresponding to the end of winter and summer, respectively. Based on the concentration of MP determined by FT-IR analysis and morphological inspection, fishes from each species were divided into two groups: ≤0.1 MP g-1 and >0.1 MP g-1. Biomarkers (general condition, neurotoxicity, biotransformation, oxidative stress) and the Integrated Biomarker Response (IBR) indicating fish general stress were determined. Fishes with more than 0.1 MP g-1 showed elevated general stress (1.2- to 1.8-fold) relative to fish with ≤0.1 MP g-1. Founders captured in March were the exception. Mullets were the most susceptible fishes to MP contamination by exhibiting poor physical condition, neurotoxicity, oxidative stress or damage, and carps were the most resilient. Low temperature and less chlorophylls (a proxy of food availability) observed in March appear to enhance the biological effects of MP.

A multiple biomarker approach to understand the effects of microplastics on the health status of European seabass farmed in earthen ponds on the NE Atlantic coast

The occurrence of microplastics (MPs) in aquaculture environments is a growing concern due to their potential negative effects on fish health and, ultimately, on seafood safety. Earthen pond aquaculture, a prevalent aquaculture system worldwide, is typically located in coastal and estuarine areas thus vulnerable to MP contamination. The present study investigated the possible relation between MP levels of European seabass (Dicentrarchus labrax) farmed in an earthen pond and its health status. More precisely, two groups of fish were established based on the lowest and highest number of MPs found collectively in their gastrointestinal tract (GIT), liver, and dorsal muscle: fish with ≤2 MP/g and fish with ≥4 MP/g. The intestinal integrity and oxidative stress biomarkers in the liver and dorsal muscle were evaluated in the established groups. No significant differences in the biometric and organosomatic parameters between groups were observed. The results indicated a significant increase in the number of acid goblet cells (GC) in the rectum of fish with higher MP levels (p = 0.016). Increased acid GC number may constitute a first defence strategy against foreign particles to protect the intestinal epithelium. No significant differences in oxidative stress biomarkers between the two fish groups were observed, namely in the activity of superoxide dismutase, catalase, glutathione reductase, and glutathione S-transferase in the liver, or in lipid peroxidation levels in the liver and dorsal muscle. The overall results suggest that MP levels were possibly related to an intestinal response but its potential implications on the health status of pond-farmed seabass warrant further investigation. Monitoring MP occurrence across stages of aquaculture production could help to elucidate the potential threats of MPs to fish health.

Micro- and Nanoplastics Produced from Textile Finishes: A Review

The problem of increasing plastic pollution has emerged as a significant societal issue. Plastics can originate from various sources, and there is growing concern among researchers to study and investigate this new category of pollution. The plastic waste is found at the macro, micro, and nanoscale, and its study has had great significance according to the perspective of posing hazardous impacts on living organisms. Given the high demand for functional textiles, the textile industries are supporting the coating of different polymeric based finishes on the surface of textile products. The plastic debris emitted from these coated finishes are in the ranges of nanometric scale, so-called polymeric nanoplastics (PNPs). With the new terminology, polymeric nanoplastics (PNPs) released from textile finishes or coatings are being increasingly mentioned, and the term fibrous microplastics (FMPs) can be seen as outdated. This study is based on an intensive review of a very novel category of debris plastics (PNPs) mostly produced from textile finishes or coatings. In fact, FMPs and PNPs released from synthetic textiles and textiles coated with plastic-based finishes during washing activities are considered to be a major cause that contributes to the current overall load of microplastics (MPs) in the environment. A link between the concentration of NPs from textile fibers and NPs from textile polymeric-based coatings in freshwater and sediments within a particular local setting and the extent of activities of the textile industry has been demonstrated. Invested efforts have been paid to consider and concentrate on plastic pollution (nanoplastics from textile polymeric coatings). We also summarize existing methodologies to elucidate the identification and proactive quantification of nanoplastics shed from the textile polymeric coatings. To this end, more than 40 studies have been done to identify the physical, chemical, and mechanical parameters and to characterize nanoplastics.

Bio inspired heuristic computing scheme for the human liver nonlinear model

In this research, a bio-inspired heuristic computing approach has been developed to solve the nonlinear behavior of the human liver, which is categorized into the liver and blood. The solutions of the human liver model are presented by using the stochastic computation procedure based on the artificial neural network (ANN) along with the optimization of genetic algorithm (GA) and interior-point (IP). A fitness function is designed through the differential form of the nonlinear human liver model and then optimized by using the hybrid competency of GAIP scheme. The correctness and exactness of the proposed approach are observed through the overlapping of the obtained (GAIP) and reference (Adams scheme) solutions, while the calculated absolute error values in good order enhance the worth of the proposed solver. The log-sigmoid transfer function together with ten numbers of neurons is executed to perform the solutions of the human liver nonlinear model. Furthermore, the statistical approaches have been applied in order to observe the reliability of the designed approach for solving the nonlinear human liver model.

Assessment of the impact of microplastic ingestion in striped red mullets from an Eastern Mediterranean coastal area (Zakynthos Island, Ionian Sea)

Monitoring microplastics (MPs) in the marine environment is an ongoing process, and our understanding of their impact on marine organisms is limited. The present study evaluates the effects of ingested MPs on the marine MP pollution bioindicator fish species Mullus surmuletus. The study follows a three-fold approach to assess the impact of MPs on marine organisms by investigating: 1) the ingestion of MPs, 2) the bioaccumulation of phthalate compounds as plastic additives, and 3) the evaluation of toxicological biochemical and cellular biomarkers. Striped red mullets were sampled in the marine protected area (MPA) of the National Marine Park of Zakynthos and coastal sites with high touristic pressure in Zakynthos Island in the Ionian Sea, Greece. Fewer ingested MPs and lower phthalate concentrations were found in fish inside the MPA compared to those sampled outside the marine park. However, no relationship was found between either phthalate concentrations or biomarker levels with the ingested MPs in the red striped mullets. Biomarker levels were influenced by season and site, but no effect could be attributed to the ingested MPs. The lack of association of biomarker responses and plasticizer bioaccumulation to MP ingestion can be explained by the low number of ingested MPs in the fish from Zakynthos coastal area as MP abundance ranged from 0.15 to 0.55 items per individual fish.

Ingestion of microplastics and microfibers by the invasive blue crab Callinectes sapidus (Rathbun 1896) in the Balearic Islands, Spain

The blue crab Callinectes sapidus Rathbun, 1896 is native to the western coasts of the Atlantic Ocean and is currently considered an invasive species in the Mediterranean Sea. In this study, we examined the stomach contents of C. sapidus to determine the frequency of occurrence of microplastics (MPs) and microfibers (MFs) in the Balearic Islands archipelago in the western Mediterranean Sea. A total of 120 individuals were collected from six locations between 2017 and 2020. Overall, 65.8% of the individuals had MPs and/or MFs particles with an average of 1.4 ± 1.6 particles ind.-1 of which an average of 1.0 ± 1.3 items ind.-1 were MFs and an average of 0.4 ± 0.8 items ind.-1 were MPs. In terms of type, fragments were the dominant type of MPs and the most common size of items ranged from between 0.5 and 1 mm (40%) followed by 1-5 mm (31%). The most prevalent polymers were low-density polyethylene (39%) and high-density polyethylene (26%). In terms of links to human activities, MP ingestion was positively correlated with an increase in drain pipes, whereas MF ingestion was positively correlated with an increase in sewage pipelines, providing evidence of potential sources and the bioavailability of these particles in various environments. This study confirms the widespread presence of MP and MF particles, even in areas that are currently managed under different protection statuses, in the stomach contents of invasive blue crab species throughout coastal communities.

Monthly microplastics change in European anchovy's (Engraulis encrasicolus) gastrointestinal tract in the Black Sea

To contribute to a better understanding of the regional dynamics of MP pollution and its potential effects on the anchovy population and human health, here we assessed the presence and characterization of microplastics (MPs) in European anchovy (Engraulis encrasicolus), which is the most caught/consumed species in the Black Sea and is of vital importance to the ecosystem. A total of 360 individuals (30 per month) were sampled from the eastern Black Sea continental shelf all year round (monthly from September 20 to Aug 21). We extracted and digested the gastrointestinal tracts (GITs) of the samples with H2O2 and characterized the MPs in the GITs by stereomicroscope and ATR-FTIR. MPs varied between 0 and 0.43 MP individual-1. The morphological structure of MPs was composed of 51 % fiber > fragment (32.7 %) > film (12.2 %) > foam (4.1 %) and polymer types as PP (42.9 %) and PE (22.4 %). In the prevalence of MP colors, black (26.5 %) > white (24.5 %) > red (22.5 %) was observed. The mean MP size was 735.32 ± 836.62 μm, with no significant correlation between the abundance and size of ingested MPs and anchovy height/weight and GIT weight. We determined that MP abundance showed substantial differences between the fishing season (0.18 ± 0.05 MP ind-1) and the banned season (0.05 ± 0.03 MP ind-1). It is essential to develop effective waste management strategies to protect the vulnerable marine ecosystems of the Black Sea and ensure sustainable exploitation of living resources in this region. These strategies should be accompanied by robust monitoring and enforcement measures to guarantee their effectiveness and compliance.

Seasonal monitoring of microplastic pollution in the Southeast Black Sea: An example of red mullet (Mullus barbatus) gastrointestinal tracts

This study investigated seasonal presence of microplastic (MP) in gastrointestinal tracts of red mullet (Mullus barbatus) sampled from the Southeast Black Sea Region. A total of 335 MPs were detected in 120 individuals. While the most MP was observed in the winter and autumn seasons, quite few MPs were found in the summer and spring seasons. MP size did not show significant difference among seasons. While all of the MPs in the autumn and spring and most of the MPs in the winter were fiber-shaped, most of the MPs in the summer were fragments. The most observed MP color for all seasons was white. While polymer structures did not show much variation in spring and summer, six different polymers were determined for both autumn and winter. In general, less MPs were detected during fishing ban period (summer) and the characteristic properties of the detected MPs suggest a MP pollution in the region due to intense fishing activities.

Microplastic Presence in the Digestive Tract of Pearly Razorfish Xyrichtys novacula Causes Oxidative Stress in Liver Tissue

Plastic pollution in the oceans is a growing problem, with negative effects on exposed species and ecosystems. Xyrichtys novacula L. is a very important fish species both culturally and economically in the Balearic Islands. The aim of the present study was to detect and categorise the presence of microplastics (MPs) in the digestive tract of X. novacula, as well as the existence of oxidative stress in the liver. For this purpose, the fish were categorised into two groups based on the number of MPs observed in the digestive tracts: a group with no or low presence of MPs (0-3 items) and a group with a higher presence of MPs (4-28 items). MPs were found in 89% of the specimens analysed, with a dominance of fibre type and blue colour. Regarding the type of polymer, polycarbonate was the most abundant, followed by polypropylene and polyethylene. For the group with a greater presence of MPs, the activities of the antioxidant enzymes glutathione peroxidase and glutathione reductase, as well as the phase II detoxification enzyme glutathione s-transferase, were higher than the activities observed in fish with little to no presence of MPs. The activities of catalase and superoxide dismutase and the levels of malondialdehyde did not show significant differences between both groups. In conclusion, these results demonstrate the presence of MPs in the digestive tract of X. novacula and the existence of an antioxidant and detoxification response, mainly based on the glutathione-based enzymes.

Research and characterization of fibrous microplastics and natural microfibers in pelagic and benthic fish species of commercial interest

The ingestion of synthetic microfibers, the most prevalent type of microplastics in marine environments, and natural fibers was assessed in Engraulis engrasicolus and Mullus barbatus, two commercially important fish species in the Mediterranean Sea. Microfibers were isolated from the fish gastrointestinal tract using a 10% potassium hydroxide solution. For the microfiber characterization, the evaluation of specific morphological features using a light microscope, coupled with the Fourier-transform infrared (FTIR) analysis of a subsample of isolated particles, was applied. The preliminary results showed the occurrence of microfibers in 53 and 60% of European anchovy and Red mullet, respectively. A mean of 6.9 microfibers/individual was detected in anchovies, while on average Red mullet samples contained 9.2 microfibers/individual. The most common colors of fibers in both species were black, blue, and transparent. Visual characterization of fibers allowed the classification of 40% of the items as synthetic microfibers. FTIR spectroscopy confirmed the visual classification by fiber morphology. Microfibers were made of different typologies of polymers, represented by cellulose, cotton, and polyester. These findings confirm as the wide distribution of fibrous microplastics, and natural microfibers may impact both pelagic and deep-sea trophic webs. Despite the presence of microfibers in fish species poses a potential risk to human health, the literature is scarce regarding studies on the uptake by commercial marine fish mostly due to methodological issues. The visual characterization, corroborated by spectroscopic techniques, may be useful to differentiate synthetic and natural fibers, representing a fast and easy method to assess fibrous microplastic pollution in commercially important fish species.

Is Wild Marine Biota Affected by Microplastics?

The present review provides detailed information on the adverse effects of MPs on wild marine organisms, including tissue damage, fish condition, oxidative stress, immune toxicity, and genotoxicity. A bibliometric analysis was carried out on CiteSpace (version 6.1.R3) (Drexel University, Philadelphia, PA, USA) to verify how many papers studied the effects on wild marine species. The results showed a total of 395 articles, but only 22 really presented data on the effects or impacts on marine biota, and of these, only 12 articles highlighted negative effects. This review shows that the observed effects in wild organisms were less severe and milder than those found in the experimental conditions. The knowledge of negative effects caused by direct ingestion of microplastics in wild animals is still limited; more efforts are necessary to fully understand the role of MPs and the adverse effects on wild marine organisms, the ecosystem, and human health.