In the last decade many studies have described the ingestion of plastic in marine animals. While most studies were dedicated to understanding the pre-ingestion processes involving decision-making foraging choices based on visual and olfactory cues of animals, our knowledge in the post-ingestion consequences remains limited. Here we proposed a theoretical complementary view of post-ingestion consequences, attempting to connect plastic ingestion with plastic-induced satiety. We analyzed data of plastic ingestion and dietary information of 223 immature green turtles (Chelonia mydas) from tropical Brazilian reefs in order to understand the impacts of plastic ingestion on foraging behavior. Generalized linear mixing models and permutational analysis of variance suggested that plastic accumulations in esophagus, stomach and intestine differed in their impact on green turtle’s food intake. At the initial stages of plastic ingestion, where the plastic still in the stomach, an increase in food intake was observed. The accumulation of plastic in the gastrointestinal tract can reduce food intake likely leading to plastic-induced satiety. Our results also suggest that higher amounts of plastics in the gastrointestinal tract may led to underweight and emaciated turtles. We hope that adopting and refining our proposed framework will help to clarify the post-ingestion consequences of plastic ingestion in wildlife.

Natural halloysite nanotubes (HNTs) with a hollow lumen are already applied in numerous fields and enter the environment in increasing quantities, which may have effects on animal and human health. However their in vivo toxicity in mammals is still largely unclear. The aim of this study is to assess acute oral toxicity of HNTs in the stomach of mice and recovery. Oral HNTs at low dose (5 mg HNTs/kg BW) for 30 days increased in daily food and water intake and promoted mouse growth with no obvious adverse effect on the stomach. The promotive effect on mouse growth disappeared after cessation of oral administration of the nanotubes. Oral HNTs for 30 days at high dose (50 mg HNTs/kg BW) induced Si and Al accumulation in the stomach, which caused oxidative stress, inflammation and iNOS-mediated damage in the organ. The damage in the stomach led to slight atrophic gastritis and reduced mouse growth. Oral HNTs-induced changes at high dose were not observed after a 30-days recovery period. The findings provided the evidence that oral HNTs-induced acute toxicity in the stomach was reversible. More importantly, this research showed that Al and Si were cleared out of the mice by hepatic excretion and renal excretion, respectively, during the recovery period. The results suggest that HNTs at low concentration in environments have no adverse effect on mice, while there are health risks to mice under severe contamination by HNTs.

Microplastics are widespread across the global oceans, yet the potential risks of the ubiquitous environmental contaminant to marine organisms has been less known. Accumulation of microplastics and associated contaminants in marine fish, may pose adverse impacts to human health via seafood consumption. This study evaluated microplastic contamination in 24 fish species collected from Beibu Gulf, one of the world’s largest fishing grounds in South China Sea. Microplastics were detected in 12 fish species at an abundance of 0.027–1.000 items individual⁻¹ and found in fish stomach, intestines and gills with the count percentage of 57.7%, 34.6% and 7.7%, respectively. Transparent fibers were observed as the predominant microplastics, which might be ingested accidently by fish or transferred through other animals at lower trophic levels. Majority of microplastics were identified as polyester (44%) and nylon (38%), whereas polypropylene (6%), polyethylene (6%), and acrylics (6%) were also found. Relatively, higher microplastic abundances were found in demersal fish compared to the pelagic species. Overall, the abundance of microplastics was documented as relatively low in the commercial fish collected from the open water of Beibu Gulf, South China Sea.

Rivers play an important role in the overall transport of microplastic pollution (1 μm to 5 mm), with fluvial dynamics expected to influence biotic interactions, particularly for fish. So far, there have been few assessments of microplastics in freshwater salmonids. The prevalence (i.e. percentage occurrence) and burden (i.e. abundance per fish) of microplastics were assessed in the gastrointestinal tracts (GITs) and stomach contents (SCs) of 58 brown trout Salmo trutta Linnaeus, 1758 sampled at six sites along the River Slaney catchment in south-east Ireland. Sites were divided into two classifications (high and low exposure) based on proximity to microplastic pollution sources, comprising three sites each. Analysis of biological traits (e.g. fish length) and diet was performed on the same fish to determine possible factors explaining microplastic burden. Microplastics were found in 72% of fish having been recovered from 66% of GITs (1.88 ± 1.53 MPs fish⁻¹) and 28% of SCs (1.31 ± 0.48 MPs fish⁻¹). Fibres were the dominant particle type recovered from GITs (67%) and SCs (57%) followed by fragments. No difference in median microplastic burden was observed between fish collected in high and low exposure sites. Microplastic burden was unrelated to fish fork length, while microplastic size distribution (100 ≤ 350 μm, 350 μm to ≤ 5 mm) was unrelated to S. trutta age class estimates. Furthermore, microplastic burden was not explained by dietary intake. Though further research is necessary, this study showed the presence of microplastics in wild S. trutta collected from an Irish riverine system, which could have further implications for top-level consumers that feed on the species, including humans. Further analysis is required to determine possible trophic linkages for the species, with respect to microplastics, and to assess the suitability of S. trutta for monitoring microplastics in river systems.

Bioaccumulation of Hg and Cd from food is a complex ecological process that has been oversimplified in the past. Common dolphins (Delphinus delphis) provide a powerful model to biomonitor metal concentrations in marine environments worldwide. We combined proportions-based nutritional geometry with metal analysis, stomach content analysis and the proximate composition of prey, to yield novel insights into the accumulation of Hg and Cd. Our analysis showed an age-related accumulation trend for Cd and Hg in kidney and liver, with highest concentrations found at 18 years of age. When viewed through the lens of nutritional ecology, Argentine anchovy (58.1 Mass %) and South American long-finned squid (22.7 Mass %), provided most of the dietary intake of protein (P) and lipids (L) (P:L ratio = 2.6:1.0) and also represented the main source for Cd and Hg levels accumulated in their bodies. This study presents unprecedented evidence on metal accumulation in relation to age and nutritional intake in a marine predator.

Human waste is a global concern, and volumes are growing rapidly. For opportunistic species, like many birds, urban waste offers alternative food which in turn may lead to plastic ingestion with potential negative effects. We assessed the incidence of plastics and other marine debris in breeding Kelp Gull (Larus dominicanus) diet at nine colonies located along ~2400 km of coastline from southern Buenos Aires to southern Chubut, Argentina, using regurgitated pellets (n = 2355) and chick stomach content samples (n = 588). Plastics were recorded at all colonies, and incidence varied between 0.0 and 16.2% in adult pellets and 0.0–12.5% in chick stomach content samples, depending on the colony, breeding stage and year. Contrary to our expectation, incidence of debris including plastics in Kelp Gull diet was relatively low despite its opportunistic feeding habits and widespread use of refuse dumps, even at colonies located close (<10 km) to these anthropogenic food subsidies.

Marine litter levels were measured in the stomach contents, hepatopancreas, and gonad tissues of crustacea decapod (Callinectes sapidus Rathbun, 1896; n = 6), a widespread alien species affecting the Lesina lagoon. Results highlight a mean of 2.5 (SD = 1.6) items/animal and indicate the presence of metals fragments (13%) and plastics (13% PE; 6.7% PET) in the stomach contents of collected individuals. No microplastic particles were detected in the hepatopancreas or in muscle tissue, while microplastic fibres (nylon, rayon, polyester) were found present in female specimen gonads. The presence of synthetic fibres in the investigated species reflects the relative contamination level in this habitat type and suggests that the blue crab could be considered a model organism for evaluating the contamination status of the study area.

Through collaboration with Inuit hunters, we examined the stomach contents of 142 seals (ringed seals [Phoca hispida; n = 135], bearded seals [Erignathus barbatus; n = 6], and one harbour seal [Phoca vitualina; n = 1]) hunted between 2007 and 2019 from communities around Nunavut to assess whether seals in the eastern Canadian Arctic ingest and retain plastics in their stomachs. The seals in this study ranged from juveniles to adults of up to 30 years of age, and 55% of the seals were males. We found no evidence of plastic ingestion in any of the seals suggesting that seals in Nunavut are not accumulating plastics (>425 μm) in their stomachs. These data provide important baseline information for future plastic pollution monitoring programs in the Arctic.

The accumulation of plastic pollutants in marine environments has many adverse effects on wildlife. In particular, marine predators are often exposed to accidental plastic ingestion, that may negatively affect survival due to the concentration of debris in the digestive tract. Among the species most vulnerable to plastic ingestion, seabirds are of major interest for conservation because of their wide foraging areas, long generation time and extended lifespan. We analysed stomach contents of 90 seabird specimens from 12 different species collected in New Caledonia to assess the local prevalence of plastic ingestion. Overall, we found plastic debris in 14.4% of sampled individuals, exclusively in procellariids: Gould's Petrel (41.2%, highest incidence), Tahiti Petrel (33.3%) and Wedge-tailed Shearwater (7.7%). To our knowledge, this study is the first characterization of plastic ingestion in seabirds from New Caledonia and our results show an overall lower ingestion prevalence compared to other assessments in the tropical Pacific.

This study estimates chemical composition of microplastic in sediments and benthic detritivores (sea cucumbers) collected from different marine rocky bottom habitat types (bank, landslide, cliff) of Salina Island (Aeolian Archipelago, Italy). Also, species richness and bottom coverings by benthic species were recorded at each sampling station. Correlations among chemical composition of microplastic in sediments and in detritivores were explored linking recorded variability to the factor “habitat type”. Results evidence that the habitat types considered in this study are characterized by wide species richness and by high percentages of bottom coverage by protected species by international conventions. In spite of the high ecological value of habitats considered in this study, microplastics were recorded both in sediments (PVC, PET, PE, PS, PA, PP) and in stomach contents of sea cucumbers (PET, PA) collected in all sampling sites, confirming the exposure of benthic species to microplastic pollution.