Effects of copper sulphate on the fatty acids profile and enzymatic activity of marine bivalve species

• Autor(a) principal: Mesquita, Andreia Filipa da Costa
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/22323
• topic: Bivalves; Sulfato de cobre; Ácidos gordos

In the past years, an intensive usage of fertilizers and pesticides has been reported, mainly in the Mediterranean region, due to the wide agriculture production required to increase food production to respond to world exponential growth of human population. Copper, with several applications at industrial and agricultural activities is often discharged in the aquatic systems and this input can lead to damages to the ecosystems and its communities. Copper sulphate, is found in pesticides and fertilizers formulations, frequently used in the agricultural practice to control the pests. These chemicals once released into the environmental may have different fates and behaviour. Due to the adverse effects copper may have on aquatic species and to the aquatic systems, it becomes pivotal to evaluate the effects of this chemical in non-target species. Thus, the present study proposes to address the toxic and biochemical impacts of copper sulphate in two important commercial bivalve species, Cerastoderma edule and Scrobicularia plana, and two size classes, big (B) and small (S). Organisms were collected at the Mondego estuary (Figueira da Foz, Portugal) and transported to the laboratory in cold boxes with water from the estuary. After a depuration period, organisms from different size classes and both species were exposed to a range of concentrations of copper sulphate (0.6 mg/L; 0.9 mg/L; 1.2 mg/L; 1.5 mg/L; 1.8 mg/L; and 2.1 mg/L to both size classes of C.edule, and 1.0 mg/L; 1.5 mg/L; 2.0 mg/L; 2.5 mg/L; 3.0 mg/L; 3.5 mg/L; 4.0 mg/L to both size classes of S. plana) under laboratorial conditions. Changes in the fatty acid profiles and at the activity of the enzymes Glutathione reductase (GR), Glutathione S-transferase (GST) and Glutathione peroxidase (GPx) and the occurrence of lipid peroxidation, by the measurement of the thiobarbituric acid reactive species (TBARS) levels, were then determined to both size classes of the two bivalve species Biochemical analyses were conducted to: 1) organisms collected in the field, 2) organisms collected at the field and under a depuration period in the lab, and 3) organisms exposed to a range of copper sulphate concentrations under laboratory conditions. The results showed C. edule is more sensitive to the chemical (LC50= 0.818 (0.595- 0.987) mg/L; 1.129 (0.968 - 1.289) mg/L, to big and small organisms, respectively) action than S. plana (LC50= 2.563 (2.229 - 2.903) mg/L; 4.705 (3.540 -12.292) mg/L, to big and small organisms, correspondingly), with the small size exhibiting higher tolerance to the compound than the big size class in both bivalve species. At the biochemical level, S. plana also present a higher nutritive value than C. edule. S. plana show greater abundance and variety of FA and essential fatty acids (EFA), namely DHA and EPA, rates than C. edule. The behaviour and enzymatic activities were also affected by the copper sulphate concentrations, although C. edule exhibited a more consistent response to the chemical exposure than S. plana with C. edule being more affected. In conclusion, this study highlights Although the lower effects in biochemical and molecular pathways of S. plana, C. edule exhibits a more the coherent behavioural pattern in terms of fatty acid content and enzymatic of C. edule suggesting the usage of this species as a good bio-indicator in ecotoxicological studies to detect the presence of copper sulphate in aquatic systems, and the determination of fatty acid profile and enzymatic activity as good biomarkers to this chemical. The muscle (foot) proved to be a suitable tissue to determine the effect of pollutants in the antioxidant defence system of bivalve species, in addition to the digestive gland and gills.