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PubMed2006

Toxicological responses in Laeonereis acuta (annelida, polychaeta) after arsenic exposure.

Several environmental pollutants, including metals, can induce oxidative stress. So, the objective of this study was to evaluate the effects of arsenic (As(III), as As(2)O(3)) on the antioxidant responses in the polychaete Laeonereis acuta. Worms were exposed to two environmentally relevant concentrations of As, including the highest previously allowed by Brazilian legislation (50 microg As/l). A control group was kept in saline water (10 per thousand) without added metal. It was observed that: (1) a peak concentration of lipid peroxide was registered after 2 days of exposure to 50 microg As/l (61+/-3.2 nmol CHP/g wet weight) compared to the control group (43+/-4.5 nmol CHP/g wet weight), together with a lowering of the activity of the antioxidant enzyme catalase (-47 and -48%, at 50 or 500 microg As/l respectively) and a higher superoxide dismutase activity (+305% at 50 microg As/l with respect to the control group); (2) a lower conjugation capacity through glutathione-S-transferase activity was observed after 7 days of exposure to 50 microg As/l (-48% compared to the control group); (3) a significant increase in As concentration was verified after 1 week of exposure to both As concentrations (50 and 500 microg/l); (4) worms exposed to As showed a limited accumulation of related methylated As species and the levels of non-toxic As species like arsenobetaine (AsB) and arsenocholine (AsC) remained unchanged during the exposure period when compared with the controls. Overall, it can be concluded that As interfered in the antioxidant defense system of L. acuta, even at low concentrations (50 microg/l) that Brazilian legislation previously considered safe. The fact that worms exposed to As showed high levels of methylated As species indicates the methylation capability of L. acuta, although the high levels of inorganic As suggest that not all the administered As(III) (as As(2)O(3)) is completely removed or biotransformed after 7 days of exposure.

Animals↗
PubMed2000

Sublethal effects of Texas brown tide on Streblospio benedicti (Polychaeta) larvae.

The Texas brown tide bloom is noted for a concordant decline in benthic biomass and species diversity. However, the link between harmful effects induced by Texas brown tide and benthos has not been demonstrated. It has been proposed there may be a larval bottleneck, where larvae, but not adults, suffer adverse effects. This study was performed to test the effect of brown tide alga, Aureoumbra lagunensis, on mortality, growth and behavior of Streblospio benedicti larvae. Growth rates and swimming speeds, but not mortality rates, of polychaete larvae were reduced in cultures with brown tide relative to Isochrysis galbana, which is about the same size as brown tide. Results from this research indicate that brown tide does have harmful sublethal effects for one dominant species of meroplanktonic larvae, which could help explain reduced adult population size.

Journal Article↗