RESUMEN
Microplastics and nanomaterials are applied in a myriad of commercial and industrial applications. When leaked to natural environments, such small particles might threaten living organisms' health, particularly when considering their potential combination that remains poorly investigated. This study investigated the physiological and biochemical effects of polyethylene (PE; 64-125 µm in size, 0.1, 1.0, and 10.0 mg·L-1) single and combined with an engineered nanomaterial applied in antifouling coatings, the copper-aluminium layered double hydroxides (Cu-Al LDH; 0.33, 1.0, and 3.33 mg·L-1) in the flatfish Solea senegalensis larvae (8 dph) after 3 h exposure, in a full factorial design. Particles ingestion, histopathology, and biochemical biomarkers were assessed. Fish larvae presented <1 PE particles in their gut, independently of their concentration in the medium. The histological health index showed minimal pathological alterations at PE combined exposure, with a higher value observed at 1 mg LDH·L-1 × 0.1 mg PE·L-1. Gut deformity and increased antioxidant defences (catalase), neurotransmission (acetylcholinesterase), and aerobic energy production (electron transport system) were observed at PE ≥ 1.0 mg·L-1. No oxidative damage (lipid peroxidation) or alterations in the detoxification capacity (glutathione-S-transferase) was observed on single and combined exposures. PE, combined or not with Cu-Al LDH, does not seem to compromise larvae's homeostasis considering levels reported so far in the marine and aquaculture environments. However, harsh effects are expected with MP contamination rise, as projections suggest.
Asunto(s)
Peces Planos , Contaminantes Químicos del Agua , Acetilcolinesterasa , Animales , Microplásticos , Plásticos , Polietileno/toxicidad , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidadRESUMEN
This study aimed to assess the biological responses of oysters from an urban estuary in Northeast Brazil, through the evaluation of biochemical and physiological biomarkers, and integrate these responses with the investigation of mercury seasonal contamination. Oysters and sediment were collected from three sites in the estuary of the Ceará River during dry and rainy seasons. Biomarkers (AchE, CaE, GST, CAT, and Condition Index) were analyzed in different tissues. Hg bioaccumulation was higher in animals sampled in the rainy season, with increases varying from 5% to 136%, compared to the dry season. The changes in biomarkers highlight already elevated stresses for the organisms at the inner portion of the estuary, near the confluence with the Maranguapinho River, mainly during the rainy season, corroborating other studies that showed ecotoxicological effects with water and sediment samples. Finally, no correlation between Hg in sediment/oyster and biomarker results was observed.
Asunto(s)
Crassostrea , Mercurio , Contaminantes Químicos del Agua , Animales , Brasil , Monitoreo del Ambiente , Estuarios , Ríos , Contaminantes Químicos del Agua/toxicidadRESUMEN
Metal bioaccumulation and toxicity to aquatic organisms depends on factors such as magnitude, duration and frequency of the exposure. The type of the exposure affects the toxicokinetic processes in the organisms. In this study, we carried out 30-day toxicity tests on juveniles of Ruditapes philippinarum exposed to increasing, continuous and pulsed exposure. Organisms were exposed to copper-spiked sediments followed by a 10-day recovery period. We assessed the interaction between the kinetics of subcellular copper partitioning and the growth response. Results showed that the growth rate of the bivalve was inversely correlated to the bioaccumulation rate and that sublethal copper concentrations stimulated the detoxification mechanisms inside the organism regardless the type of the exposure. However, a large stimulatory effect on growth was observed during the recovery period, associated with significant negative accumulation rate values and dependent on the type of antecedent exposure. This suggested that on individual and short-term basis pulsed exposures have a more adverse effect compared to increasing or continuous exposure scenarios.