Plastic in the inferno: Microplastic contamination in deep-sea cephalopods (Vampyroteuthis infernalis and Abralia veranyi) from the southwestern Atlantic

A review of plastic debris in the South American Atlantic Ocean coast - Distribution, characteristics, policies and legal aspects

The presence of plastics in the oceans has already become a pervasive phenomenon. Marine pollution by plastics surpasses the status of an emerging threat to become a well-established environmental problem, boosting research on this topic. However, despite many studies on the main seas and oceans, it is necessary to compile information on the South American Atlantic Ocean Coast to identify the lack of research and expand knowledge on marine plastic pollution in this region. Accordingly, this paper conducted an in-depth review of monitoring methods, sampling, and identification of macroplastics and microplastics (MPs) in water, sediments, and biota, including information on legal requirements from different countries as well as non-governmental initiatives. Brazil was the country with the highest number of published papers, followed by Argentina. MPs accounted for 75 % of the papers selected, with blue microfibers being the most common morphology, whereas PE and PP were the most abundant polymers. Also, a lack of standardization in the methodologies used was identified; however, the sites with the highest concentrations of MPs were the Bahía Blanca Estuary (Argentina), Guanabara Bay (Brazil), and Todos os Santos Bay (Brazil), regardless of the method applied. Regarding legislation, Uruguay and Argentina have the most advanced policies in the region against marine plastic pollution due to their emphasis on the life cycle and the national ban on certain single-use plastics. Therefore, considering its content, this expert review can be useful to assist researchers dealing with plastic pollution along the South American Atlantic Ocean Coast.

Does the microplastics ingestion patterns and polymer composition vary across the oceanic zones? A case study from the Indian coast

This study explores microplastic (MP) presence in the gastrointestinal tracts of deep-sea fish from the Central Indian Ocean, off the Indian coast. Among the 27 species examined, 19 showed MP contamination, averaging 2.68 ± 0.30 (±SE) MPs per individual. Polymer analysis via FTIR and micro-Raman identified several types, including polyethylene terephthalate (PET), polyvinyl alcohol (PVA), polypropelene (PP), polyvinyl acetate (PVC), polyurethane (PU), polytetrafluoroethylene (PTFE), polyaniline (PANI), polymethyl methacrylate (PMMA), and polyethersulfone (PES), with PET being the most prevalent (33.33 %). MP ingestion was higher in benthopelagic fish and those at higher trophic levels, as indicated by comparisons across oceanic zones. Niche partitioning analysis suggests feeding behaviour as a primary influencer of MP ingestion in deep-sea fish rather than habitat or trophic level. The study proposes the potential use of deep-sea fish as indicators for assessing microplastic pollution across oceanic zones and deep-sea regions through bycatch monitoring.

Snapshot Sampling May Not Be Enough to Obtain Robust Estimates for Riverine Microplastic Loads

Wastewater treatment plants (WWTPs) have been described as key contributors of microplastics (MPs) to aquatic systems, yet temporal fluctuations in MP concentrations and loads downstream are underexplored. This study investigated how different sampling frequencies (hourly, weekly, and monthly) affect MP estimates in a stream linked to a single WWTP. Utilizing fluorescence microscopy and Raman spectroscopy, considerable hourly variations in MP concentrations were discovered, while the polymer composition remained consistent. This temporal variability in MP loads was influenced by MP concentration, discharge rates, or a mix of both. These results show a high uncertainty, as relying on sparse snapshot samples combined with annual discharge data led to significant uncertainties in MP load estimates (over- and/or underestimation of emissions by 3.8 billion MPs annually at this site). Our findings stress the necessity of higher-frequency sampling for better comprehending the hydrodynamic factors influencing MP transport. This improved understanding enables a more accurate quantification of MP dynamics, crucial for downstream impact assessments. Therefore, preliminary reconnaissance campaigns are essential for designing extended, representative site-monitoring programs and ensuring more precise trend predictions on a larger scale.

Microplastics in the Indian and South Atlantic oceans translocate to gills, digestive glands, and muscle of the chokka squid Loligo reynaudii

Comparative microplastic (MP) data for cephalopods between oceans is scarce. Our aim was to quantify, characterise, and compare MPs in gills, digestive gland, and mantle of chokka squid from the South Atlantic Ocean (SAO) and Indian Ocean (IO) off the coast of South Africa. South African squid had more MPs compared with other studies (means = 2.0 and 0.4 in SAO and IO squid mantle, respectively). Blue fibres were dominant. Identifiable MPs were polyethylene. Despite IO water having higher MP concentrations than the SAO, SAO squid had higher MP concentrations. Dilution by growth is the likely reason for the lower MP concentrations. Fibres were shorter in SAO than IO squid. However, we could not explain why fibre and mantle lengths from both oceans were positively correlated. Squid may not be the best indicator of marine MPs. The characteristics of MPs in squid can be used to track stocks and migrations.

A reliable method to determine airborne microplastics using quantum cascade laser infrared spectrometry

The number of studies dealing with airborne microplastics (MPs) is increasing but sampling and sample treatment are not standardized, yet. Here, a fast and reliable method to characterize MPs is presented. It involves the study of two passive sampling devices to collect atmospheric bulk deposition (wet and dry deposition) and three digestion methods (two alkaline-oxidative and an oxidative) to treat the samples. The alkaline-oxidative method based on KOH and NaClO was selected for a mild organic matrix digestion. In addition, some operational parameters of a high-throughput quantum cascade laser-based infrared device (LDIR) were optimized: an effective automatic tiered approach to differentiate fibres from particles (>90 % success in validation) and a criterion to establish positive matches when comparing an unknown spectrum against the spectral database (proposed match index > 0.85). The procedural analytical recoveries were very good for particles (82-90 %) and slightly lower for fibres (62-73 %). Finally, the amount and type of MPs deposited at a sub-urban area NW Spain were evaluated. Most common polymers were Polyethylene (PE), Polypropylene (PP) and Polyethylene terephthalate (PET). The deposition rates ranged 98-1220 MP/m2/day, ca. 1.7 % of the total collected particles. More than 50 % of the total MPs deposited were in the 20-50 μm size range, whereas fibres were mostly in the 50-500 μm size range.

Larger Common River Frogs (Amietia delalandii) have Fewer and Shorter Tissue Microplastic Fibres than Smaller Frogs

Little is known about microplastics (MPs) in adult frogs. We investigated MPs in adult Common River Frogs (Amietia delalandii) from Potchefstroom, South Africa. Five kinds of samples were analysed: natural water, water used to rinse the skin, skin, intestine, and the remainder of the body (corpus). Tissues were digested. Microplastics occurred in all frogs and sample types (1128 MPs counted). Fibres were the most prevalent MP. Fibre lengths were between 28 and 4300 μm, either polyester or polyvinyl alcohol. MPs in skin were likely derived from the ambient, and MPs in the corpus from translocation via the skin. Fibres in tissues were significantly shorter in larger frogs, a phenomenon we provisionally assign to in situ biodegradation. Microplastics in frogs can potentially be transferred through the food web to higher trophic levels. This study provides the first evidence of MPs in adult frog tissues and avenues for further investigations.

Microplastic enrichment capacity of Ctenochaetus striatus from the habitat environment - An example in Xisha, South China Sea

Microplastic pollution is a widespread concern in the global marine environment. In this study, microplastic pollution status in Xisha waters was investigated. Microplastics were found in all seawater samples, and 90.76 % of C. striatus samples were detected with microplastics. The average abundance of microplastics in seawater samples was 0.64 ± 0.39 items/L, and the abundance of microplastics in the gills and gastrointestinal tracts (GITs)of C. striatus was 1.14 ± 0.41 items/L and 1.80 ± 0.49 items/L, respectively. Shapes of microplastics in the seawater and in the gills and GITs of C. striatus were mainly fibers and films, and the majority of the particle sizes being <1 mm, and the polymers were mainly PET. In addition, the abundance of microplastics in the gills and GITs of C. striatus was positively correlated with that in the seawater, and the correlation was higher in the gills than in the GITs, which means that the accumulation of microplastics in the gills was more closely related to their habitats. The positive correlation between microplastic abundance in the gills and GITs of C. striatus and its body size may be due to the fact that larger individuals have greater energetic demands, require more energy requirements, consume more food, and thus increase the chances of ingesting microplastics.

Microplastics as contaminants in the Brazilian environment: an updated review

Microplastics have long been present in marine and terrestrial environments and have emerged in recent decades as a global environmental concern. This pollutant has been detected with increasing frequency in Brazilian territory and herein primarily highlights current information and developments about the quantity, distribution, techniques of identification, origins, and sources of microplastics and related pollutants in the Brazilian environment. We evaluated 79 publications from 2018 to December 2022, and some aspects can be highlighted: 27% of studies were published in the Journal Marine Pollution Bulletin; 22% of all studies were conducted in São Paulo city; and 52% of all microplastics found were collected from biota followed by sediment samples. According to the findings given here, microplastics in Brazilian habitats, which can reach concentrations of 4367 to 25,794 items m-2 in sediments, are becoming a serious problem in the Anthropocene age, and some topics regarding the open questions in this area were pointed out in this review.

Spatio-temporal distribution of microplastic pollution in surface sediments along the coastal areas of Istanbul, Turkey

Microplastics (MPs) have become prevalent in various environmental compartments, including air, water, and soil, attracting attention as significant pollutant parameters. This study investigated the prevalence of MP pollution in surface sediments along Istanbul's Marmara Sea, encompassing the megacity and the Bosphorus. A comprehensive sampling approach was employed, covering 43 stations across four seasons and depths ranging from 5 to 70 m. The objective was to assess the impact of terrestrial, social, and industrial activities on MPs. The average concentrations varied per season, with fall, winter, spring, and summer values recorded as 2000 ± 4100, 1600 ± 3900, 4300 ± 12,000, and 9500 ± 20,300 particles/kg-DW. The study identified river stations in the Golden Horn and sea discharge locations as hotspots for high concentrations. Notably, the dominant shape shifted from fibers in fall, winter, and spring to fragments during summer, coinciding with mucilage occurrences. The study identified 11 different polymers, with polyethylene (44 %) and polypropylene (31 %) being the most common.

Transcriptomic analysis of oxidative stress mechanisms induced by acute nanoplastic exposure in Sepia esculenta larvae

Nanoplastics (NPs), as a new type of pollutant with a size small than 1 μm, are ubiquitous and harmful to organisms. There has been an increasing amount of research concerning the effects of NPs on organisms over recent years, especially on aquatic animals. However, there is a limited study on the impact of NPs on mollusk cephalopods. In this research, Sepia esculenta, belonging to Cephalopoda, Coleoidea, Sepioidea, was selected to explore the effects caused by NPs exposure. The S. esculenta larvae were exposed to polystyrene NPs (PS-NPs) with diameter 50 nm (100 mg/L) for 4 h. The detection of oxidative stress biomarkers displayed an obvious increase in SOD (superoxide dismutase) activity and MDA (malondialdehyde) level. Then, RNA-Seq was performed to explore the oxidative stress response at mRNA level. The transcriptome analysis demonstrated that the expression of 2,570 genes was affected by PS-NPs. Besides, the signaling pathways of ribosome, ribosome biogenesis in eukaryotes, proteasome, and MAPK were enriched. This study not only provides novel references for understanding the mechanisms of oxidative stress response induced by NPs, but also reminds us to follow with interest the influence of acute exposure to NPs.

From the light blue sky to the dark deep sea: Trophic and resource partitioning between epipelagic and mesopelagic layers in a tropical oceanic ecosystem

The connection between epipelagic and deep-sea mesopelagic realms controls a variety of ecosystem processes including oceanic carbon storage and the provision of harvestable fish stocks. So far, these two layers have been mostly addressed in isolation and the ways they connect remain poorly understood. Furthermore, both systems are affected by climate change, exploitation of resources, and increasing pervasion of pollutants. Here we use bulk isotopes of δ¹³C and δ¹⁵N of 60 ecosystem components to evaluate the trophic linkage between epipelagic and mesopelagic ecosystems in warm oligotrophic waters. Additionally, we we conducted a comparison of isotopic niche sizes and overlaps across multiple species to evaluate how environmental gradients between epipelagic and mesopelagic ecosystems shape ecological patterns of resource use and competition between species. Our database comprises siphonophores, crustaceans, cephalopods, salpas, fishes, and seabirds. It also includes five zooplankton size classes, two groups of fish larvae, and particulate organic matter collected at different depths. Through this wide taxonomic and trophic variety of epipelagic and mesopelagic species, we show that pelagic species access resources originating from different food sources, mostly autotrophic-based (epipelagics) and microbial heterotrophic-based (mesopelagics). This leads to a sharp trophic dissimilarity between vertical layers. Additionally, we show that trophic specialization increases in deep-sea species and argue that food availability and environmental stability are among the main drivers of this pattern. Finally, we discuss how the ecological traits of pelagic species highlighted in this study can respond to human impacts and increase their vulnerability in the Anthropocene.

From prey to predators: Evidence of microplastic trophic transfer in tuna and large pelagic species in the southwestern Tropical Atlantic

Plastic pollution is present in most marine environments; however, contamination in pelagic predators, including species of economic interest, is still poorly understood. This study aims to access the macro- and microplastic contamination in tuna and large pelagic species and verify whether a trophic transfer occurs from prey to tunas captured by two fleets in the Southwestern Tropical Atlantic (SWTA). We combined different methodological approaches to analyse the intake of macro- and microplastics. In addition to examining the plastics in the fish' stomachs, we investigated the contamination in the prey retrieved from the guts of predators. A low frequency of occurrence (3%) of macroplastic was detected in the tuna and large pelagic species; conversely, we observed a high frequency of microplastic in the tuna's stomachs (100%) and prey analysed (70%). We evinced the trophic transfer of microplastics by analysing the ingestion rate of particles in prey retrieved from the tuna stomachs. In the 34 analysed prey, we detected 355 microplastic particles. The most contaminated prey were cephalopods and fishes of the Bramidae family. The most frequent microplastic shapes in both prey and tuna stomachs were foams, pellets and fibres (<1 mm). A variety of polymers were identified; the most frequent were styrene-butadiene rubber (SBR), polyamide (PA), polyethylene terephthalate (PET) and polyethylene (PE). Our findings enhance scientific knowledge of how the ecological behaviour of marine species can affect microplastic intake.

Stressors of emerging concern in deep-sea environments: microplastics, pharmaceuticals, personal care products and deep-sea mining

Although most deep-sea areas are remote in comparison to coastal zones, a growing body of literature indicates that many sensitive ecosystems could be under increased stress from anthropogenic sources. Among the multiple potential stressors, microplastics (MPs), pharmaceuticals and personal care products (PPCPs/PCPs) and the imminent start of commercial deep-sea mining have received increased attention. Here we review recent literature on these emerging stressors in deep-sea environments and discuss cumulative effects with climate change associated variables. Importantly, MPs and PPCPs have been detected in deep-sea waters, organisms and sediments, in some locations in comparable levels to coastal areas. The Atlantic Ocean and the Mediterranean Sea are the most studied areas and where higher levels of MPs and PPCPs have been detected. The paucity of data for most other deep-sea ecosystems indicates that many more locations are likely to be contaminated by these emerging stressors, but the absence of studies hampers a better assessment of the potential risk. The main knowledge gaps in the field are identified and discussed, and future research priorities are highlighted to improve hazard and risk assessment.

Exploring microplastic contamination in reef-associated fishes of the Tropical Atlantic

Microplastics (MPs) are ubiquitous in marine compartments, and their transboundary distribution favours the dispersion and accumulation of particles in ecosystems. This study investigated MP contamination in four coastal fish species (Haemulon squamipinna, Chaetodon ocellatus, Syacium micrurum, and Alphestes afer) from the southwestern Tropical Atlantic. An alkaline treatment was applied to extract MPs from the digestive tracts, and a Laser Direct Infrared (LDIR) system was used to identify polymers. All species analysed were contaminated with MPs, with Alphestes afer being the most contaminated (1.45 ± 1.09 MPs individual^-1; frequency of occurrence 80 %). No significant differences were found in the number and size of detected particles among species. The most common shapes were fibres and films, and polyethylene was the most abundant polymer. This study provides important baseline data on MP contamination in coastal fish species inhabiting complex habitat areas relevant for conserving marine biodiversity.

How does the internal distribution of microplastics in Scylla serrata link with the antioxidant response in functional tissues?

Crabs can live in diverse lifestyles in both water and benthic environments, which are the basin of microplastics (MPs) inputs. Edible crabs with large consuming quantity, e.g., Scylla serrata were subjected to accumulate MPs in their tissues from surrounding environments and generate biological damages. However, no related research has been conducted. In order to accurately assess the potential risks to both crabs and humans consuming MPs contaminated crabs, S. serrata were exposed to different concentrations (2, 200 and 20,000 μg/L) of polyethylene (PE) microbeads (10-45 μm) for 3 days. The physiological conditions of crabs and a series of biological responses, including DNA damage, antioxidant enzymes activities and their corresponding gene expressions in functional tissues (gills and hepatopancreas) were investigated. PE-MPs accumulated in all tissues of crabs with concentration- and tissue-dependent manner, which was assumed to be via the internal distribution initialized by gills' respiration, filtration and transportation. Significantly increased DNA damages were observed in both gills and hepatopancreas under exposures, however, the physiological conditions of crabs showed no dramatic alterations. Under low and middle concentration exposures, gills energetically activated the first line of antioxidant defense to against oxidative stress, e.g., superoxide dismutase (SOD) and catalase (CAT), but lipid peroxidation damage still occurred under high concentration exposure. In comparison, SOD and CAT composed antioxidant defense in hepatopancreas tended to collapse under severe MPs exposure and the defense mechanism attempted to switch to the secondary antioxidant response by compensatively stimulating the activities of glutathione S-transferase (GST), glutathione peroxidase (GPx) and the content of glutathione (GSH). The diverse antioxidant strategies in gills and hepatopancreas were proposed to be closely related to the accumulation capacity of tissues. The results confirmed the relation between PE-MPs exposure and antioxidant defense in S. serrata, and will help to clarify the biological toxicity and corresponding ecological risks.

Understanding the interactions between cephalopods and marine litter: A research evaluation with identification of gaps and future perspectives

Litter is known to negatively affect numerous marine organisms, but the extent of such impacts is not well known for several groups, including cephalopods. Considering the ecological, behavioral and economic importance of these animals, we reviewed the types of interactions between cephalopods and litter in the scientific literature, to evaluate impacts and knowledge gaps. We found 30 papers, which included records of microplastic ingestion and the transfer of synthetic microfibers along the food web. The largest number of records involved litter use as shelter, and the common octopus was the most frequent species. At first sight, litter use as shelter could appear to be a potential positive effect, but it is necessary to clarify the implications of this choice and its long-term consequences. Regarding ingestion and trophic transfer, further research is needed to elucidate its occurrence and impacts on cephalopods and their predators, including humans.

Influencing factors for microplastic intake in abundant deep-sea lanternfishes (Myctophidae)

Plastic debris is ubiquitous in the hydrosphere. Yet, we lack an understanding of contamination among deep-sea species and primarily how each trait can influence microplastic intake. We investigated microplastic contamination in the digestive tract of hyper-abundant mesopelagic lanternfishes (n = 364 individuals) from the Southwestern Tropical Atlantic, captured from 90 to 1000 m depth. Overall, microplastics were detected in most individuals analysed (frequency of occurrence = 68 %). Large microplastics, mostly of a filamentous shape were the most frequent, followed by smaller fragments and foams. Microplastics made of high-density polymers (PET, PVC, PA, SBR rubber) were more prevalent than low-density ones (PE, EVA and PBD rubber), especially under deeper layers. Larger microplastics were detected in lanternfishes captured off the northeastern Brazilian coast (mean 0.88 ± SE 0.06 mm) compared to those from around the Rocas Atoll and Fernando de Noronha Archipelago (0.70 ± 0.07 mm; p≤ 0.05), ∼350 km from the continent. Moreover, lanternfishes that migrate from the upper mesopelagic (200-500 m) to the epipelagic layers (<200 m) had simultaneously the highest intake and the smallest particles (1.65 ± 0.17 particles individual^-1 and 0.55 ± 0.07 mm; p≤ 0.05). Biological mediated transport of microplastics from the epipelagic to the mesopelagic waters was evinced, but fishes foraging in shallower layers had the lowest intake (1.11 ± 0.10 part. ind.^-1; p≤ 0.05). Furthermore, the jaw length was positively associated with an increment in microplastic intake (Incidence Rate Ratio = 1.1; p≤ 0.05). The lanternfishes that preferably prey upon fish larvae are more prone to microplastic intake than their counterparts, which forage mostly on crustaceans and gelatinous zooplankton (p≤ 0.05).

Adsorption abilities and mechanisms of Lactobacillus on various nanoplastics

As a new type of pollutants, nanoplastics (NPs), which are easily ingested by humans from food wraps, salt, drinking water, have been widely detected in various water environments, and are a threat to human health. It is therefore urgent to develop an efficient method to remove NPs from the diet or relief its harm. In the present study, the possibility of a well-known human probiotic, lactic acid bacteria (LAB), was evaluated to remove NPs from food as an absorbent. The results indicated that LAB from infant feces could efficiently absorb three types NPs, i.e. polypropylene (PP), polyethylene (PE), and polyvinyl chloride (PVC) with the adsorption rates of PP > PE > PVC (PP 78.57%, PE 71.59%, PVC 66.57%) and the Nile red-stained NPs being aggregated on the surfaces of Lactobacillus cells. The smaller the particle size, the stronger the ability of NP adsorption on the cell surface. The hydrophobicity of NPs and bacterial cells affected the adsorption process. The measurement of adsorption rates of different cell components indicated that the overall adsorption effect of cell was better than that of individual cell component. The results of molecular dynamics analysis revealed that adsorption was mainly caused by electrostatic interactions, van der Waals forces, and hydrogen bonds. The hydrophobic interaction was also involved in adsorption process. Overall, this research may provide new information for developing new strategies for NPs removal in intestinal environment.

First assessment of debris pollution in the gastrointestinal content of juvenile Magellanic penguins (Spheniscus magellanicus) stranded on the west south Atlantic coasts

This paper provides the first evidence of debris pollution, including plastic, in juvenile Magellanic penguins (Spheniscus magellanicus) found stranded on the Atlantic coast of southern Buenos Aires Province, Argentina. Macro-, meso- and microparticles of anthropogenic origin were observed in 100 % of the studied birds, with debris abundance ranging between 33 and 200 items/bird. Microparticles represented 91 % of the total debris and 97 % of them were fibers. Black particles were the most abundant (30 %), followed by transparent (26 %), blue (14 %), yellow (10.3 %), and red (10 %). Infrared and Raman spectroscopy identified 62.7 % of the total particles as plastics, with polypropylene (27.8 %) and polyester (21.6 %) being the most abundant polymers. Semi-synthetic cellulosic fibers, metallic particles, and pigments were also found. The presence of metallic microparticles was suggested for the first time in penguins. Stranded juvenile Magellanic penguins are proposed as promising bioindicators of plastic pollution in the South Atlantic.

The pollution of microplastics in sediments: The ecological risk assessment and pollution source analysis

The occurrence of microplastics (MPs) pollution in sediments has brought huge challenges to the development of society. Pollution control of MPs in sediments has become an inevitable requirement for current society. This requires implementing targeted pollution control measures in high MPs ecological risk areas and controls MPs discharge in pollution source. Existing studies lack in-depth understanding in MPs ecological risk assessment and MPs pollution source analysis, this limits the pollution control of MPs in sediments. In this study, the studies of MPs pollution in sediments from 2013 to 2022 were reviewed. The results showed that the environmental problems caused by MPs pollution in marine sediments have been widely discussed over the past decade. And the occurrence of MPs pollution in sediments brought potential threat to marine ecology and human food supply. Furthermore, pollution load index, polymer risk index and potential ecological risk index of MPs were frequently used in the existing ecological risk assessment of MPs in sediments. A large amount of monitoring data and simulation data is conducive to improving these MPs ecological risk assessment indicators. This can provide a useful reference for managers to formulate MPs pollution control measures. And MPs types and land-use types can provide basis to analyze the pollution source of MPs in sediments. Developing more accurate MPs detection and analysis technologies can further improve current MPs pollution source analysis system. This is conducive to control the discharge of MPs in the pollution source. In future studies, more complete MPs ecological risk assessment system and MPs pollution source analysis system should be established to control the pollution of MPs in sediments.

First Evidence of Microplastics in the Yolk and Embryos of Common Cuttlefish (Sepia officinalis) from the Central Adriatic Sea: Evaluation of Embryo and Hatchling Structural Integrity and Development

Once they reach the aquatic environment, microplastics (MPs) are accidentally ingested by aquatic biota, thus entering the food chain with possible negative effects. The present study investigated, for the first time, MP presence in cuttlefish (Sepia officinalis) eggs and their association with embryonic development. Cuttlefish eggs were sampled from four different sites along the Marche region (Senigallia, Ancona, Numana, and San Benedetto del Tronto). Embryo and hatchling biometric parameters were evaluated and the internal structural integrity was examined through histological analysis. MPs were detected and characterized in embryos and yolk samples. MPs were identified in all sites (size < 5 µm), however, their presence has not been associated with an impairment of either embryo or hatchling internal structures. Noteworthy, the highest number of MPs (in both yolk and embryo samples) were found in Numana (37% of the total amount), where the lowest hatchling size was observed. On the other hand, the highest embryo mantle length was associated with the lowest number of MPs detected (9%) in Ancona. Overall, only MP fragments and sphere types (74 and 26%, respectively) were observed, and the most frequent polymers were Polyvinyl chloride (52%), Polypropylene, and Cellulose acetate (15% both). Further studies are needed to assess the possible MP effects on the yolk quality and assimilation.

Polystyrene microplastic ingestion induces the damage in digestive gland of Amphioctopus fangsiao at the physiological, inflammatory, metabolome and transcriptomic levels

Microplastics are ubiquitous in the aquatic and terrestrial ecosystem, increasingly becoming a serious concern for aquatic organism health. However, information regarding the effects of microplastics on cephalopods is remain limited to date. Amphioctopus fangsiao, an important economic species in cephalopods, can serve as a potential indicator of environmental pollution due to its short life expectancy and high metabolic rates. Here, to explore the toxic effects during the microplastic stress response, we analyzed the growth performance, histopathological damage, oxidative stress biomarkers, metabolomic and transcriptomic response in digestive gland of A. fangsiao under different concentrations (0, 100 and 1000 μg/L) of commercial polystyrene microplastics (MPS) exposure (5 μm, sphere) for 21 days. The results showed that MPS exerted a huge influence on the growth performance of A. fangsiao. The oxidative stress and inflammation in digestive gland of A. fangsiao were also detected after exposure to MPS. In addition, most of the altered metabolites observed in the metabolic analysis were related to inflammation, oxidative stress and glucolipid metabolism. Transcriptome analysis detected the differentially expressed genes (DEGs) and the significantly enriched KEGG pathways associated with glycolipid metabolism, inflammation and DNA damage. Collectively, our results indicate that excessive environmental microplastic exposure will cause toxicity damage and then initiate the detoxification mechanism in A. fangsiao digestive gland to maintain homeostasis. This study revealed that microplastic can cause adverse consequences on cephalopods, providing novel insights into the toxicological effect of microplastic exposure.

Toxic effects of polystyrene microplastics on the intestine of Amphioctopus fangsiao (Mollusca: Cephalopoda): From physiological responses to underlying molecular mechanisms

Microplastics are broadly used and among the most studied environmental pollutants due to their potential impacts on organisms and human health. Amphioctopus fangsiao (Cephalopoda: Octopodidae) is an important commercial species in the Pacific Northwest and is very popular among consumers owing to its rich nutritional value and fresh flavor. However, the toxic effects of microplastic exposure on A. fangsiao, including phenotypical effect and underlying molecular mechanism, remain limited. In this study, the octopus A. fangsiao were exposed to microplastics (polystyrene microplastics, Micro-PS) at concentrations of 100 and 1000 μg/L for 21 days, and then the physiological response, histopathological analysis, biomarkers of oxidative stress and glycolipid metabolism, microbiome perturbations and transcriptomic profiles in the intestines were performed. Results demonstrated that Micro-PS exposure had distinct adverse effects on the food intake of A. fangsiao. Histological analysis revealed that Micro-PS exposure has resulted in histopathological damage, thus causing early inflammation of the intestine. Oxidative stresses, metabolic disorders and microbiome perturbations were also detected in the intestine of A. fangsiao based on physiological biomarkers and microbiome analyses. Moreover, transcriptome analysis detected the differentially expressed genes (DEGs) and significantly enriched KEGG pathways in response to oxidative stress, glycolipid metabolism, DNA damage and transmembrane transport of intestinal cells, revealing distinct toxic effects at the molecular level. In summary, Micro-PS exposure has a strong impact on the intestines of A. fangsiao. For the first time, this study uses multiple approaches based on the physiological and biochemical response as well as transcriptional regulation analysis. The first assessment of the toxic impact of this species under Micro-PS exposure is also reported.

A review of sources, status, and risks of microplastics in the largest semi-enclosed sea of China, the Bohai Sea

The largest semi-enclosed sea of China, the Bohai Sea, serves as an important sink of microplastics (MPs) originated from terrestrial and marine sources. This study summarized potential sources and migration pathways of MPs in the Bohai Sea and reviewed the abundance and characteristics of MPs in water, sediments, and organisms. Coastal anthropogenic activities (i.e., plastic production, agricultural activities, and industrial and domestic sewage discharge) and marine origins (i.e., aquaculture, marine litters, and transportation) might accelerate the MPs enrichment in the Bohai Sea. The abundance of MPs ranged from 0.07 to 5200 items/m³ in the seawater, mainly influenced by the application of different trawl nets/sieves with different sizes (0.005-0.33 mm). Sediments of coastal rivers contained the MPs ranging from 56.7 to 1795 items/kg, significantly higher than that of the Bohai Sea (6.24-461.6 items/kg). Among organisms, the average abundance of MPs was the lowest in zooplanktons (0.03 items/animal), significantly lower than that in invertebrates (1.39 items/animal) and fish (2.12 items/animal), but no biomagnification of MPs was observed. The preliminary risk assessment indicated that seawater in the Liaodong Bay had medium ecological risk of MPs while other bays of the Bohai Sea had minor risks. To make the ecological risk of MPs quantifiable and comparable, future research priorities are recommended to focus on more frequent field surveys, standardization of sampling methods, and establishment of toxicity database of common polymer types of MPs in the Bohai Sea.

Methodological considerations in studying digestive system physiology in octopus: limitations, lacunae and lessons learnt

Current understanding of cephalopod digestive tract physiology is based on relatively “old” literature and a “mosaic of data” from multiple species. To provide a background to the discussion of methodologies for investigating physiology we first review the anatomy of the cephalopod digestive tract with a focus on Octopus vulgaris, highlighting structure-function relationships and species differences with potential functional consequences (e.g., absence of a crop in cuttlefish and squid; presence of a caecal sac in squid). We caution about extrapolation of data on the digestive system physiology from one cephalopod species to another because of the anatomical differences. The contribution of anatomical and histological techniques (e.g., digestive enzyme histochemistry and neurotransmitter immunohistochemistry) to understanding physiological processes is discussed. For each major digestive tract function we briefly review current knowledge, and then discuss techniques and their limitations for the following parameters: 1) Measuring motility in vitro (e.g., spatiotemporal mapping, tension and pressure), in vivo (labelled food, high resolution ultrasound) and aspects of pharmacology; 2) Measuring food ingestion and the time course of digestion with an emphasis on understanding enzyme function in each gut region with respect to time; 3) Assessing transepithelial transport of nutrients; 4) Measuring the energetic cost of food processing, impact of environmental temperature and metabolic rate (flow-through/intermittent respirometry); 4) Investigating neural (brain, gastric ganglion, enteric) and endocrine control processes with an emphasis on application of molecular techniques to identify receptors and their ligands. A number of major knowledge lacunae are identified where available techniques need to be applied to cephalopods, these include: 1) What is the physiological function of the caecal leaflets and intestinal typhlosoles in octopus? 2) What role does the transepithelial transport in the caecum and intestine play in ion, water and nutrient transport? 3) What information is signalled from the digestive tract to the brain regarding the food ingested and the progress of digestion? It is hoped that by combining discussion of the physiology of the cephalopod digestive system with an overview of techniques and identification of key knowledge gaps that this will encourage a more systematic approach to research in this area.

Enrichment and dissemination of bacterial pathogens by microplastics in the aquatic environment

Microplastic pollution and associated impacts in the aquatic environment are spreading at an alarming rate worldwide. Plastic waste is increasing in the environment, and microplastics (MPs) are becoming a growing issue because they serve as vectors for pathogen transmission. This is the first comprehensive review that specifically addresses MPs as a source and vector of pathogenic bacteria, mainly associated with genera Vibrio, Pseudomonas, Acinetobacter, and so on, which are discovered to be more abundant on the aquatic plastisphere than that in the surrounding wastewater, freshwater, and marine water ecosystems. The horizontal gene transfer, chemotaxis, and co-selection and cross-selection could be the potential mechanism involved in the enrichment and dissemination of bacterial pathogens through the aquatic plastisphere. Further, bacterial pathogens through aquatic plastisphere can cause various ecological and human health impacts such as disrupted food chain, oxidative stress, tissue damages, disease transmission, microbial dysbiosis, metabolic disorders, among others. Last but not least, future research directions are also described to find answers to the challenging questions about bacterial pathogens in the aquatic plastisphere to ensure the integrity and safety of ecological and human health.

The role of mesopelagic fishes as microplastics vectors across the deep-sea layers from the Southwestern Tropical Atlantic

Microplastics (MPs; <5 mm) are a macro issue recognised worldwide as a threat to biodiversity and ecosystems. Widely distributed in marine ecosystems, MPs have already been found in the deep-sea environment. However, there is little information on ecological mechanisms driving MP uptake by deep-sea species. For the first time, this study generates data on MP contamination in mesopelagic fishes from the Southwestern Tropical Atlantic (SWTA) to help understand the deep-sea contamination patterns. An alkaline digestion protocol was applied to extract MPs from the digestive tract of four mesopelagic fish species: Argyropelecus sladeni, Sternoptyx diaphana (Sternoptychidae), Diaphus brachycephalus, and Hygophum taaningi (Myctophidae). A total of 213 particles were recovered from 170 specimens, and MPs were found in 67% of the specimens. Fibres were the most common shape found in all species, whereas polyamide, polyethylene, and polyethylene terephthalate were the most frequent polymers. The most contaminated species was A. sladeni (93%), and the least contaminated was S. diaphana (45%). Interestingly, individuals caught in the lower mesopelagic zone (500-1000 m depth) were less contaminated with MPs than those captured in the upper mesopelagic layer (200-500 m). Our results highlight significant contamination levels and reveal the influence of mesopelagic fishes on MPs transport in the deep waters of the SWTA.

Environmental Stressors and Pathology of Marine Molluscs

Mollusca is one of the most species-rich phylum of the Animal Kingdom, comprising a wide range of both terrestrial and aquatic organisms [...]