Browsing by Author "Teixeira, Rafaela Paulo"
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- Impact of polyamide microfibers on marine organisms using Mytilus galloprovincialis as a modelPublication . Teixeira, Rafaela Paulo; Guerreiro, Pedro Miguel Guerreiro da Costa; Castro, MargaridaPlastic is a major source of pollution/contamination in the marine environment, with important impacts on organisms, trophic webs and ecosystems. A major component of these plastic derivatives are polyamide microfibers (PAMF) that originate from synthetic fabrics. Contrary to the so-called microplastics, the impacts of these microfibers on marine species has received little attention. This thesis aims at evaluating the impact of such microfibers on the physiological processes of marine organisms and its possible introduction in the food webs. To do so, Mytilus galloprovincialis served as a model, to investigate the physiological impact of PAMF. The quantities of microfibers ingested, accumulation in the digestive tract, effects on growth variables, utilization of energetic substrates and oxidative stress were studied. The experimental setup included the establishment of a system of 12 tanks distributed by 4 levels of concentration of PAPF in the water (three replicates per treatment level): 0 (Control), 30 (30 PAMF/L), 100 (100 PAMF/L) and 200 (200 PAMF/L). Sixty mussels of similar sizes (length 2- 5mm) were placed in each tank and the experiment was run over a 45-day period. At days 15, 30 and 45, 5 specimens from each tank were sacrificed to obtain information on growth (shell biometrics), weight (soft tissues and shell weight), presence of microfibers in the tissues (mantle, gills, digestive glands, oral cavity and byssus) and catalase activity (in digestive glands and gills). Mortality was registered whenever the tanks were monitored (every other day). Results indicate that the PAMF levels tested do not cause mortality in M. galloprovincialis and do not affect shell size. However, significant differences in the weight regarding the shell weight and the dry weight or organic tissue were observed, decreasing with the increase of PAMF concentration in the water. The number of fibers in the different structures was similar (maximum values around 60) with no pattern of retention of the fibers (increase with time or level of PAMF), with the exception of the digestive glands where, for the levels 30, 100 and 200, the retention of fibers increased from day 15 to 30 and then decreased to day 45. Differences in the CAT activity were observed in the digestive glands and gills, in which, overall, the antioxidant activity increased with the increase of PAMF. In conclusion the polyamide microfibers in the water where M. galloprovincialis were grown did not have a highly significant impact of its health along the 45 days of the experiment since it did not cause mortality, likely due to the high capacity of this species to acclimate and adapt. However, future studies will be conducted to better understand the impact of these plastics’ derivatives in marine organisms.