Use of resources and microplastic contamination throughout the life cycle of grunts (Haemulidae) in a tropical estuary

Microplastic adulteration in homogenized fish and seafood - a mid-infrared and machine learning proof of concept

The objective of this study was to assess the ability of utilizing attenuated total reflection mid-infrared (ATR-MIR) spectroscopy in combination with machine learning techniques to classify the presence of different types of microplastics in artificially adulterated fish and seafood samples. Different polymers namely poly-vinyl chloride (PVC), polycarbonate (PC), polystyrene (PS), polypropylene (PP) and low (LDPE) and high-density polyethylene (HDPE) were mixed with homogenized fish and seafood samples. Homogenized samples were analyzed using MIR spectroscopy and classification models developed using machine learning algorithms such as partial least squares discriminant analysis (PLS-DA). The results of this study revealed that it was possible to identify between adulterated and non-adulterated samples as well as the different microplastic types added to the homogenized samples using ATR-MIR spectroscopy. This study confirmed the ability of combining machine learning methods with ATR-MIR spectroscopy to directly analyze microplastic adulteration in fleshy foods such as fish and seafood. This proof-of-concept study can be utilized and extended to monitor the presence of plastics either in a wide range of fleshy foods or along the entire food value chain.

Do Freshwater Fish Eat Microplastics? A Review with A Focus on Effects on Fish Health and Predictive Traits of MPs Ingestion

Microplastics (MPs) have received increasing attention in the last decade and are now considered among the most concerning emerging pollutants in natural environments. Here, the current knowledge on microplastic ingestion by wild freshwater fish is reviewed with a focus on the identification of possible factors leading to the ingestion of MPs and the consequences on fish health. Within the literature, 257 species of freshwater fishes from 32 countries have been documented to ingest MPs. MPs ingestion was found to increase with rising level of urbanization, although a direct correlation with MPs concentration in the surrounding water has not been identified. MPs ingestion was detected in all the published articles, with MPs presence in more than 50% of the specimens analyzed in one study out of two. Together with the digestive tract, MPs were also found in the gills, and there is evidence that MPs can translocate to different tissues of the organism. Strong evidence, therefore, exists that MPs may represent a serious risk for ecosystems, and are a direct danger for human health. Moreover, toxicological effects have also been highlighted in wild catches, demonstrating the importance of this problem and suggesting the need for laboratory experiments more representative of the environmental situation.

The fate of plastic litter within estuarine compartments: An overview of current knowledge for the transboundary issue to guide future assessments

Plastics can enter biogeochemical cycles and thus be found in most ecosystems. Most studies emphasize plastic pollution in oceanic ecosystems even though rivers and estuaries are acknowledged as the main sources of plastics to the oceans. This review detected few studies approaching the transboundary issue, as well as patterns of estuarine gradients in predicting plastic distribution and accumulation in water, sediments, and organisms. Quantities of plastics in estuaries reach up to 45,500 items m^-3 in water, 567,000 items m^-3 in sediment, and 131 items per individual in the biota. The role of rivers and estuaries in the transport of plastics to the ocean is far from fully understood due to small sample sizes, short-term approaches, sampling techniques that underestimate small plastics, and the use of site-specific sampling rather than covering environmental gradients. Microfibres are the most commonly found plastic type in all environmental matrices but efforts to re-calculate pathways using novel sampling techniques and estimates are incipient. Microplastic availability to estuarine organisms and rising/sinking is determined by polymer characteristics and spatio-temporal fluctuations in physicochemical, biological, and mineralogical factors. Key processes governing plastic contamination along estuarine trophic webs remain unclear, as most studies used "species" as an ecological unit rather than trophic/functional guilds and ontogenetic shifts in feeding behaviour to understand communities and intraspecific relationships, respectively. Efforts to understand contamination at the tissue level and the contribution of biofouling organisms as vectors of contaminants onto plastic surfaces are increasing. In conclusion, rivers and estuaries still require attention with regards to accurate sampling and conclusions. Multivariate analysis and robust models are necessary to predict the fate of micro- and macroplastics in estuarine environments; and the inclusion of the socio-economic aspects in modelling techniques seems to be relevant regarding management approaches.

The need to investigate continuums of plastic particle diversity, brackish environments and trophic transfer to assess the risk of micro and nanoplastics on aquatic organisms

Plastic particles are ubiquitous in marine and freshwater environments. While many studies have focused on the toxicity of microplastics (MPs) and nanoplastics (NPs) in aquatic environments there is no clear conclusion on their environmental risk, which can be attributed to a lack of standardization of protocols for in situ sampling, laboratory experiments and analyzes. There are also far more studies concerning marine environments than fresh or brackish waters despite their role in the transfer of plastics from continents to oceansWe systematically reviewed the literature for studies: (1) using plastics representative of those found in the environment in laboratory experiments, (2) on the contamination of plastic particles in the continuum between fresh and marine waters, focusing in particular on estuaries and (3) on the continuum of contamination of plastic particles between species through trophic transfer in aquatic environments. We found that the exposure of aquatic organisms in the laboratory to plastic particles collected in the environment are very scarce. Moreover, plastic exposures of estuarine species in the laboratory are generally carried out for a single salinity and a single temperature that do not reflect the fluctuating environmental conditions of estuaries. Finally, the trophic transfer of plastic particles is mainly studied in the laboratory through simple food chains which are not representative of the complexity of the trophic networks observed in the aquatic environment. We pointed out that future studies in the laboratory should include both MPs and NPs sampled in the environment and focus on the precise characterization of the composition and surface of these plastics as well as on their absorbed pollutants, additives or biofilms. Moreover, investigations must be continued concerning the toxicity of plastic particles in brackish water environments such as estuaries and the trophic transfer of plastic particles in complex food chains.

Review of current trends, advances and analytical challenges for microplastics contamination in Latin America

Microplastics accumulation is an emerging environmental issue and a threat to marine life and human health. There is a growing number of investigations on the abundance and distribution of microplastics in different water bodies and biota worldwide, with relatively few studies conducted in Latin America, however, the current knowledge of microplastics sources, occurrence, transport, fate and potential impacts remains largely unexplored. This review presents the current trends and advances of microplastics on a lesser known region of the world by compiling the research performed to date in different environmental compartments. The sampling techniques and methods for microplastics extraction in the existing literature data are also summarized. Among 78 published studies reviewed, 34% of studies were from Brazil and 46% of studies have mainly focused on biota. The main findings showed that microplastics are not negligible across Latin America significantly varying in their distribution, with the prevalence of fibers comprising 62% of the total. Polyethylene, polypropylene, polyethylene terephthalate and polystyrene have been identified as the most common polymer types, accounting for 80% of the total. Limited studies and lack of standardized methodologies render difficulties to establish fundamental information on microplastics abundance and types in most countries of this region. Therefore, this review will primarily serve as a baseline when evaluating the environmental relevance of microplastics in Latin America and would stimulate discussions focusing on this topic, calling for more research in future.

Thermal analysis and enhanced visual technique for assessment of microplastics in fish from an Urban Harbor, Mediterranean Coast of Egypt

Enhanced visual counting technique coupled with combustion analysis and differential scanning calorimetry (DSC) was applied to assess microplastics (MPs) contamination in fish digestive tracts from Eastern Harbor, Egypt, to provide a simple and economic method for MPs assessment. This was the first study in Egypt to quantify MPs in fish. Plastic particles were detected in all fish samples, represented by seven thermoplastic polymers. The average number of MPs was at its highest level in Siganus rivulatus, Diplodus sargus, and Sardinella aurita (7527, 3593, and 1450MPs fish^-1, resp.) and the lowest in Sphyraena viridensis and Atherina boyeri (46 and 28MPs fish^-1, respectively). The average weight of MPs as measured by combustion ranged from 302mg kg^-1 in S. rivulatus to 2mg kg^-1 in Terapon puta.

Assessing urban microplastic pollution in a benthic habitat of Patagonia Argentina

Plastic pollution in the oceans has become a global problem, but its documentation is disparate around the world. We assess the abundance and type of microplastics in three benthic matrices: mussels, small fishes, and bottom water; in three sites nearby Puerto Madryn city (Patagonia, Argentina). Microplastics were present in the three matrices for all sites sampled. The average amounts of items observed were 1.6 and 0.3 per total wet weight in fishes and mussels, respectively, and 10.5 per liter in bottom water. Mussels and fishes presented a difference of microplastics size comparing with the surrounding bottoms waters; fishes also presented color discrimination, suggesting the necessity of more than one bioindicator to perform microplastic pollution monitoring. Moreover, small fishes had more MPs in their gastrointestinal tracts than bigger ones. The present study is the first one about the interaction between MPs and small aquatic organisms in coastal marine environments from Patagonia.

Assessing microplastic uptake and impact on omnivorous juvenile white seabream Diplodus sargus (Linnaeus, 1758) under laboratory conditions

Previous laboratory feeding experiments, representing the state-of-the-art methodology to investigate microplastic (MP) ingestion and its impact for fish, tend to disregard both the significance of applying realistic MP densities and the potential relevance of biofilm-coating for ingestion probability. This experiment assessed the uptake of either pristine or biofilm-coated MP particles and the physiological impacts for juvenile white seabream for MP concentrations consistent with those found in the field along with natural prey over a course of 3.5 weeks. Results indicate the ability of juvenile D. sargus to discriminate between edible and non-edible prey. A distinct preference for biofilm-coated over pristine particles could not be verified. No significant impact on growth and condition was found except for high levels of MP ingestion. The outcomes highlight the importance of performing MP feeding experiments mimicking natural conditions to reliably assess the impact of MP on early life stages of fish.

Plastic intake does not depend on fish eating habits: Identification of microplastics in the stomach contents of fish on an urban beach in Brazil

This study aims to identify, classify, quantify the ingested microplastic by marine teleost fish, in order to analyze the relationship between microplastic and trophic guilds. Food items of 214 individuals of Opisthonema oglinum, Bagre marinus, Cathorops spixii, Sciades herzbergii, Chloroscombrus chrysurus, Conodon nobilis, Haemulopsis corvinaeformis were analyzed. The species were classified according to their trophic guilds (zoobenthivorous or opportunistic/omnivorous). All species ingested microplastic and contamination occurred independently of the trophic guild. Of the sampled fish, 55% were contaminated by microplastic. The most consumed categories were blue (28%) and transparent filaments (20%). Raman spectroscopy measurements detected that most sampled filament corresponds to blue synthetic fiber (polyester). This study can contribute by filling gaps in knowledge regarding sandy beach impacts, which are environments so highly threatened by human activities around the world and are neglected in terms of use and conservation plans.

Ecology of microplastics contamination within food webs of estuarine and coastal ecosystems

•

Microplastics contamination of food webs can be approached as part of estuarine ecosystem ecology.

•

Standard sampling designs to study estuarine ecology allow comparisons along time and across space.

•

The proposed methods detect shifts in fish feeding habit and to demonstrate the diversity of interactions among pollutant, environment and biota.

The aim was to describe a methodology developed to study the relationship among the spatio-temporal patterns of habitat utilization, feeding ecology and microplastics (MPs) contamination across the different ontogenetic phases of fishes belonging to different trophic levels and living along the riverine-estuarine-coastal food web. The Goiana Estuary‘s water column was examined for the seasonal and spatial variation of MPs and their quantification relative to zooplankton, demersal fish species contamination following the same sampling design. The density of MPs in the water column determines their bioavailability. Interest in studies on MPs distribution in relation to spatial and temporal variation of environmental factors and fauna are increasing in quantity and quality. If the ecological strategies presented in this study were replicated in other estuary, comparisons could be made in order to describe how ecosystems work. Standard protocols for sampling, extraction, enumeration and classification of MPs and others pollutant ingested by fishes have been developed and are presented here to encourage comparisons. Standardized and comparable sampling designs and laboratory procedures are an important strategy in order to devise and transfer managerial solutions among different sites and comparisons along time when studying the same environment.

Trace analysis of polystyrene microplastics in natural waters

The development of quantitative and qualitative analytical methods to assess micro-plastics (MPLs) and nano-plastics (NPLs) content in the environment is a central issue for realistic risk assessment studies. However, the quantitative analysis continues being a critical issue, in particular for MPLs from 100 μm down to the nano-sized range in complex environmental samples. This paper evaluates the potential of mass spectrometry for the analysis of MPLs and NPLs. The performance of different techniques including matrix-assisted laser desorption ionisation (MALDI) coupled to time-of-flight mass spectrometry (TOF-MS), liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS), and the ambient ionisation approaches as desorption electrospray ionisation (DESI) and direct analysis real-time (DART), were assessed for the study of polystyrene (PS) MPLs and NPLs in natural waters. A method based on LC-HRMS, equipped with an atmospheric pressure photoionisation source (APPI), operated in negative conditions for the quantitative analysis of PS MPLs and NPLs in natural waters, was developed. The chromatographic separation was achieved using an advanced polymer chromatographic (APC) column using toluene isocratic as the mobile phase. The optimal analytical method showed an instrumental limit of detection (ILOD) of 20 pg and methods limits of detection and quantification around 30 pg L^-1 and 100 pg L^-1, respectively. And, recoveries of 60 and 70% in samples from rivers and the marine coast, respectively. The performance of the new method was proved by the analysis of fortified samples and natural seawater samples.

Effects of pollution on marine organisms

This review covers selected 2018 articles on the biological effects of pollutants, including human physical disturbances, on marine and estuarine plants, animals, ecosystems, and habitats. The review, based largely on journal articles, covers field and laboratory measurement activities (bioaccumulation of contaminants, field assessment surveys, toxicity testing, and biomarkers) as well as pollution issues of current interest including endocrine disrupters, emerging contaminants, wastewater discharges, marine debris, dredging, and disposal. Special emphasis is placed on effects of oil spills and marine debris due largely to the 2010 Deepwater Horizon oil blowout in the Gulf of Mexico and proliferation of data on the assimilation and effects of marine debris. Several topical areas reviewed in the past (e.g., mass mortalities ocean acidification) were dropped this year. The focus of this review is on effects, not on pollutant sources, chemistry, fate, or transport. There is considerable overlap across subject areas (e.g., some bioaccumulation data may be appear in other topical categories such as effects of wastewater discharges, or biomarker studies appearing in oil toxicity literature). Therefore, we strongly urge readers to use keyword searching of the text and references to locate related but distributed information. Although nearly 400 papers are cited, these now represent a fraction of the literature on these subjects. Use this review mainly as a starting point. And please consult the original papers before citing them.

Dynamics of Marine Debris Ingestion by Profitable Fishes Along The Estuarine Ecocline

The dynamics of microfilament (<5 mm) ingestion were evaluated in three species of snooks. The ingestion of different colours and sizes of microfilaments were strongly associated with the spatio-temporal estuarine use and ontogenetic shifts of snooks. Their feeding ecology was also analysed to assess dietary relationships with patterns of contamination. All species were highly contaminated with microfilaments. The highest ingestion of microfilaments occurred in the adults, when fishes became the main prey item and also during the peak of fishing activities, in the rainy season. This suggests that trophic transfer, in addition to periods of high availability of microfilaments are important pathways for contamination. The ingestion of microfilaments of different colours and sizes was likely influenced by input sources. Blue microfilaments were frequently ingested, and appear to have both riverine and estuarine inputs, since they were ingested in all seasons and habitats. Purple and red microfilaments were more frequently ingested in the lower estuarine habitats. The length of microfilaments was also associated with environmental variability. Longer microfilaments were ingested in habitats with greater riverine influence, the opposite was observed for shorter microfilaments. Therefore, microfilament contamination in snooks are a consequence of their ecological patterns of estuarine uses through different seasons and life history stages.

Use of estuarine resources by top predator fishes. How do ecological patterns affect rates of contamination by microplastics?

This study assessed the seasonal patterns of habitat utilization, feeding ecology and microplastic contamination in different ontogenetic phases of sympatric snooks (Centropomus undecimalis and C. mexicanus) inhabiting a tropical estuary. More than 50% of snooks, in all ontogenetic phases, ingested microplastics (1.5 ± 0.1 and 1.4 ± 0.1 particles ind^-1). Juveniles migrated to nursery grounds in the upper estuary, during the early dry (C. undecimalis 6.5 ± 2.8 ind^-1) (p < 0.01) and early rainy seasons (C. mexicanus 4.1 ± 1.9 ind^-1). There, they fed mostly on invertebrates (Polychaeta) (p < 0.01), and became contaminated by microplastics (C. undecimalis: 0.8 ± 0.4 particles ind^-1; C. mexicanus: 1.7 ± 0.5 particles ind^-1). Sub-adults of both species forage principally in the estuarine habitats after shifting their diet from invertebrates (shrimps) in the upper reaches (1806.4 ± 1729.6 mg ind^-1) to pelagic fishes (R. bahiensis) in seaward habitats (2507.7 ± 1758.4 mg ind^-1). During feeding continues the contamination by microplastics (3.1 ± 0.8 part. ind^-1). Adults use the adjacent coastal as feeding and spawning grounds during the rainy season. In this phase, snooks are mostly piscivorous (R. bahiensis: up to 5303.8 ± 3213.4 mg ind^-1), but also ingest penaeid shrimp as complementary item (up to 175.9 ± 156.7). Microplastics contamination rates increased towards the adult phase, with maximum contamination coinciding with peaks of fish ingestion, suggesting trophic transfer of microplastics. The lower estuary and adjacent coastal zone were important contamination sites, especially during the rainy season (up to 3.1 ± 0.8 part. ind^-1) (p < 0.01), when fishery activities is intense and river basin runoff increases. Consequently, the availability of microplastics is higher during this time of year in the lower portion of the estuary. Snooks had similar prey preferences, but the use of different habitats along the life cycle of each species avoids overlaps in estuarine use and minimizes competition.

Distribution, sources and consequences of nutrients, persistent organic pollutants, metals and microplastics in South American estuaries

Estuarine pollution imposes rapid, increasing and lasting environmental modifications. In the present review, especial attention is given to estuaries in South America (SA), where legislation, policies and actions to guarantee environmental quality remain ineffective. There, the majority of estuaries face uncontrolled occupation of its margins by urban and industrial centres, agriculture and aquaculture expansion, water extraction and flow control. The lack of basic sanitation and poor environmental management (including territories within Marine Protected Areas) often lead to hydrological alterations, high nutrient loads, and the presence and dynamics of pollutants (nutrient loads, persistent organic pollutants (POPs), metals and plastic debris) along the entire estuarine ecocline. Organic enrichment has increased dissolved oxygen consumption, with wide spatio-temporal variability along latitudes and estuarine gradients. The toxicity, biogeochemistry and availability of metals and POPs depend on the annual fluctuations of salinity, water renewal, dissolved oxygen levels, suspended particulate loads, sediment mobility, grain size and composition at the sink. Plastic debris from land sources are widespread in estuaries, where they continue to fragment into microplastics. River basins are the main contributors of plastics to estuaries, whose transportation and accumulation are subjected to interannual water flow variations. Although some systems seems to be in a better condition in relation to others around the world (e.g. Goiana and Negro estuaries), many others are among the most modified worldwide (e.g. Guanabara Bay and Estero Salado System). We propose that, estuarine conservation plans should consider year-round fluctuations of the ecocline and the resulting cycles of retention and flush of environmental signals and their influence on trophic webs over the whole extent of estuarine gradients.

Differential toxicity of functionalized polystyrene microplastics to clams (Meretrix meretrix) at three key development stages of life history

Little knowledge is available on impact of microplastics (MPs) on the bivalve larvae at different developmental stages throughout their life history, especially for metamorphic stage. Therefore, this study aims to evaluate the toxic responses of carboxylated (PS-COOH) and amino (PS-NH₂) polystyrene MPs on the developing clam larvae at three key life stages, i.e., fertilized eggs, D-veliger larvae, and umbo larvae. PS-COOH and PS-NH₂ significantly decreased the hatching rates by 5.79-39.5% and developmental rates by 4.78-7.86% of the clam larvae relative to the unexposed clam larvae. The toxicity of MPs followed the order: hatching stage > metamorphosis > D-veliger larvae stage, showing stage-dependent toxic effects. Moreover, PS-NH₂ with a smaller hydrodynamic diameter showed a greater toxicity to the developing larvae compared to PS-COOH. Our study highlighted the stage-dependent toxic effects of MPs on the developing clam larvae, thus posing ecological risks to population succession of marine bivalves and aquatic ecosystems.