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This study aimed to evaluate B[ a ]P and low-density polyethylene microplastics (MPs) toxicty, alone and in mixture (0.03 to 30 μg L−1 of B[ a ]P; and 5, 50 and 500 mg L−1 for MPs). Five mg L−1 of MPs is considerably higher than commonly reported environmental concentrations, although it has been reported for marine environments. Individual (sea urchin embryo-larval development and mortality of mysids) and sub-individual responses (LPO and DNA damage in mysids) were assessed. The toxicity increased as the B[ a ]P concentration increased, and microplastics alone did not cause toxicity. B[ a ]P toxicity was not modified by the lowest concentration of MPs (5 mg L−1), but at higher MPs concentrations (50 and 500 mg L−1), the effects of B[ a ]P on sea urchin development and in biomarkers in mysids were diminished. Microplastics interacted with B[ a ]P in seawater, reducing its toxicity, probably due to adsorption of B[ a ]P to the surface of microplastics. [Display omitted] • Microplastics are important carriers of contaminants and can alter their toxicity. • Biological responses in two species of marine invertebrates were assessed. • Microplastics and B[ a ]P interact modifying the toxicity of the isolated elements. • B[ a ]P toxicity was not modified by environmental concentrations of microplastics. • B[ a ]P toxicity decreased at higher concentrations of microparticles. [ABSTRACT FROM AUTHOR]

Microplastics, including plastic pellets, get stranded on sandy beaches. They persist in the oceans for long periods and frequently carry contaminants. Acute and chronic toxicity has been observed when marine organisms are exposed to high densities of plastic pellets in laboratory assays. We investigated the toxicity of beach-stranded plastic pellets on macrobenthic populations (Excirolana armata ; Crustacea; Isopoda) under natural conditions (in situ). We simulated different pellets densities on a beach not contaminated by pellets, exposing isopods for 6 h and testing possible behavioral responses (i.e. , vertical displacement) and mortality effects. No effect was observed on vertical displacement, but higher mortality was reported for organisms exposed to plastic pellets. The lowest pellet density tested commonly found in coastal areas was sufficient to trigger mortality. We also observed that lethargic individuals (near-death) were preyed on by the healthy individuals remaining in the test chambers. [Display omitted] • Plastic pellets were tested in field ecotoxicological assays for benthic macrofauna. • The presence of few pellets was enough to induce toxicity, regardless of density. • Pellets did not induce mortality in organisms tested individually, only in groups. • Cannibalism and necrophagy events were observed in isopods exposed to plastic pellets. • Intraspecific interactions should be considered for ecotoxicological effects. [ABSTRACT FROM AUTHOR]

Marine protected areas (MPAs) are vulnerable to many pressures, including pollution. However, environmental quality monitoring in these areas traditionally relies on only water chemistry and microbiological parameters. The goal of the current study was to investigate the role of a set of biomarkers in different target organs (liver, kidney, and gills) of fish in order to assess the environmental quality of an MPA (MTs, GPx, GST, GSH, DNA damage, LPO, AChE, and condition index). Chemical analyses were also performed on liver and muscle tissues to evaluate metal body burdens, and PAHs were identified in bile. A demersal fish ( Cathorops spixii) that is widely consumed by the local population was used as bioindicator species, and the results were integrated using multivariate analysis. The use of the biomarker approach allowed for the identification of both seasonal and spatial variations in pollution sources around the Environmental Protected Area of Cananéia-Iguape-Peruíbe (APA-CIP). Higher metal body burdens associated with biological responses were found in the sites under the influence of urban areas during the dry season, and they were found in the sites under the influence of the Ribeira de Iguape River (RIR) during the rainy season. The liver was found to be more responsive in terms of its antioxidant responses, whereas gills were found to be more responsive to biomarkers of effect. These results show that this set of biomarker analyses in different organs of fish is a useful tool for assessing chemical pollution in an MPA. [ABSTRACT FROM AUTHOR]