Biochemical responses in bivalve mollusks are commonly employed in environmental studies as biomarkers of aquatic contamination. The present study evaluated the possible influence of salinity (35, ...25, 15 and 9
ppt) in the biomarker responses of
Crassostrea gigas oysters exposed to diesel at different nominal concentrations (0.01, 0.1 and 1
mL.L
−
1
) using a semi-static exposure system. Salinity alone did not resulted in major changes in the gill's catalase activity (CAT), glutathione
S-transferase activity (GST) and lipid peroxidation levels (measured as malondialdehyde, MDA), but influenced diesel related responses. At 25
ppt salinity, but not at the other salinity levels, oysters exposed to diesel showed a strikingly positive concentration-dependent GST response. At 25
ppt and 1
mL.L
−
1
diesel, the GST activity in the gills remained elevated, even after one week of depuration in clean water. The increased MDA levels in the oysters exposed to diesel comparing to control groups at 9, 15 and 35
ppt salinities suggest the occurrence of lipid peroxidation in those salinities, but not at 25
ppt salinity. The MDA quickly returned to basal levels after 24
h of depuration. CAT activity was unaltered by the treatments employed. High toxicity for 1
mL.L
−
1
diesel was observed only at 35
ppt salinity, but not in the other salinities. Results from this study strongly suggest that salinity influences the diesel related biomarker responses and toxicity in
C. gigas, and that some of those responses remain altered even after depuration.
► Salinity strongly influences the effects caused by diesel in oyster. ► Induction of GST activity by diesel could still even after one-week depuration. ► Salinity alone did not cause alteration in oyster's biomarkers responses. ► Valuable information for biomonitoring procedures using a worldwide farmed bivalve.
Crassostrea rhizophorae is a euryhaline oyster that inhabits mangrove areas, which are widely distributed along the Brazilian coast. The aim of this study was to investigate the effects of salinity ...(9, 15, 25, and 35
ppt) on the activities of glutathione
S-transferase (GST), glucose 6-phosphate dehydrogenase (G6PDH), catalase (CAT), and acetylcholinesterase (AChE) in the digestive gland of this species after exposure to diesel oil for 7 days at nominal concentrations of 0.01, 0.1, and 1
ml
L
−1 and after depuration for 24
h and 7 days. GST activity increased in a diesel oil concentration-dependent manner at salinities 25 and 15
ppt and remained slightly elevated even after depuration periods of 24
h and 7 days. No changes were observed in the activities of G6PDH, CAT, and AChE in the oysters exposed to diesel and depurated. Based on these results, GST activity in the digestive gland of
C. rhizophorae might be used as a biomarker of exposure to diesel oil in sites where the salinity is between 15 and 25
ppt, values usually observed in mangrove ecosystems.
Dissertação (mestrado) - Universidade Federal de Santa Catarina. Programa de Pós-Graduação em Biotecnologia.
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As regiões costeiras vêm recebendo nas últimas décadas um significativo aporte de contaminantes de origem antropogênica, incluindo o petróleo e seus derivados. Como conseqüência disso, ecossistemas como os manguezais, caracterizados por possuir amplas variações de salinidade, são alguns dos ecossistemas mais afetados e vulneráveis. A ostra-do-mangue Crassostrea rhizophorae (Mollusca: Bilvalvia), um molusco eurihalino e osmoconformador, com ampla distribuição na costa brasileira, pode ser utilizado como um organismo sentinela em programas de biomonitoramento. O objetivo deste estudo foi avaliar a influência da salinidade (35, 25, 15 e 9) sobre a
