This study documents the occurrence of microplastic (<5mm), mesoplastics (5-20mm) and macroplastic (>20mm) in Atlantic cod (Gadus morhua), a common and economically important species of marine fish in Norway. Fish stomachs (n=302) were examined from six different locations along the coast of Norway. Three percent of the individual stomachs contained items identified by Fourier transform infrared spectroscopy (FTIR) as synthetic polymers. Bergen City Harbour was a hotspot with 27% of the cod examined found to contain plastic. Polyester was the most frequently detected polymer. All bar one of the stomachs that contained plastic were full of organic stomach content, suggesting a plastic gut clearance rate similar to the ingested food. It is proposed that stomach fullness is an important metric in order to avoid underestimations when assessing the levels of microplastic ingested by fish.
The aim of this study was to characterize concentration- and time-dependent responses in juvenile Atlantic cod (Gadus morhua) following exposure for one and three weeks to the water-soluble fraction (WAF) of three weathered oils: Arabian Light crude oil (ALC), North Sea crude oil (NSC) and ship-diesel. The sum of polycyclic aromatic hydrocarbons (PAH) in water was highest after one week of exposure and within environmentally relevant concentrations. PAH metabolites in bile confirmed exposure to and uptake of PAHs. Hepatic cytochrome P450 1A (CYP1A) gene expression (mRNA quantification) increased dramatically following exposure to all three oil types (fold-change up to 165) and there was a time lag between gene and protein expression. Hepatic CYP1A protein concentration and ethoxyresorufin-O-deethylase (EROD) activity were more variable among individuals and treatments than gene expression. EROD activity in liver and gills increased in fish exposed to WAF from the two crude oils, but not in fish exposed to WAF from diesel. Exposure to diesel appeared to induce oxidative stress to a greater extent than exposure to crude oils. Other biomarkers (glutathione S-transferases, acetylcholine esterase, vitellogenin) did not appear to respond to the exposure and hence did not discriminate among oils. Biomarker responses in cod after exposure to weathered crude oils and diesel suggested that the CYP1A system and oxidative stress markers have the highest potential for discriminating among different oil types and to monitor the environmental consequences of spills.
<p>Rivers have been identified as an important pathway for the release of plastic waste to the oceans, connecting land-based sources to the marine environment. Asian rivers, in particular, have been highlighted by several published studies as contributing a considerable proportion of global macro- and microplastic release. To evaluate this, several parallel projects (ASEANO, SINOPLAST, INOPOL) have commenced environmental monitoring of riverine plastic contamination in China, India, and several ASEAN countries. Monitoring is being undertaken in selected study catchments, which have been identified based on their geographical context and their relevance to global plastic contamination. They include several rivers that have been reported as being amongst the most contaminating systems in the world. Macroplastic flows in the active river channel will be assessed, as well as the role of the riverbank zone in the storage and transport of plastic waste. Monitoring of riverine microplastic contamination will also be included in some countries. The aims of this environmental monitoring is to: i) provide estimates for the flux of plastics to the ocean; ii) identify appropriate and optimum methods for routine monitoring of riverine plastic contamination; iii) supply qualitative and quantitative data on macroplastic flows and contamination to support social science research that is also taking place within these river catchments; and iv) provide data for the calibration and validation of riverine plastic transport models.</p><p>This presentation will give an overview of monitoring plans and preliminary findings and experiences from these ongoing projects. This will include a discussion about the ways in which monitoring methods have been adapted to river systems with different morphologies and flow regimes, and to satisfy different research questions across the projects. The complexities associated with undertaking environmental monitoring in large river systems will also be addressed.</p>
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