Trophic Chain Organochlorine Pesticide Contamination in a Highly Productive Upwelling Area in Southeastern Brazil.

Organochlorine pesticides (OCP) are legacy anthropogenic compounds known to persist for several years in the environment. The continuous use of some OCP, such as DDT, after restrictions in developing countries are cause of concern, due to their deleterious effects to marine life and humans. Studies assessing OCP contamination in coastal environments are still scarce in South America and there is a need to understand the impacts from trophic chain accumulation of these pollutants in marine life. In this study, we have assessed OCP levels in muscle and liver and estimated the biomagnification factor in several upwelling system trophic chain members, including fish, squid, and marine mammal from Southeastern Brazil. DDT degradation product DDE was the OCP detected in the highest concentrations in Franciscana dolphins (Pontoporia blainvillei), 86.4 ng·g-1 wet weight, and fish muscle and liver. In general, higher OCP levels were found in liver than in muscle, except for croaker. Biomagnification factors (BMF) of OCP in the top predator P. blainvillei and the carnivorous cutlass fish (Trichiurus lepturus) were on average between 0.2 and 1.8. Continued OCP monitoring in this region is warranted to better understand the distribution and fate of these compounds over time, with the goal to establish strategies for the conservation of local dolphin species and to assess human health risks from local coastal region populations.

Accumulation and toxic effects of microcystin in tilapia (Oreochromis niloticus) from an eutrophic Brazilian lagoon.

Microcystin (MC) accumulation and depuration in environmentally exposed tilapia (Oreochromis niloticus) at a chronically contaminated eutrophic lagoon was studied. This is one of the scarce reports on microcystin accumulation in bile of environmentally exposed fish, and gonad MC accumulation in the field, in contrast to laboratory exposure experiments. Results show that preferential MC accumulation in the environment occurred in tilapia fish muscle, followed by gonads, liver and, finally, bile. Biliary MC excretion in in situ conditions indicates elimination from the body to a certain degree. High gonad MC bioaccumulation is of concern, since this could indicate potential reproductive problems in this species. This study also demonstrated that tilapia shows similar oxidative stress responses (in the form of reduced glutathione, GSH) in the environment as those observed in laboratory exposed fish. MC dietary intake values for tilapia muscle and liver were above the limits imposed by international legislations, indicating that the local human population should exercise care when ingesting this species as a part of their diet and that human ingestion of MC-contaminated samples should be carefully monitored.

Metal, metallothionein and glutathione levels in blue crab (Callinectes sp.) specimens from southeastern Brazil.

Metal concentrations (Cu, Pb, Zn and Cd) were determined in muscle, gills, soft tissues and eggs in male, non-ovigerous and ovigerous female Callinectes sp. specimens from a reference site in Southeastern Brazil. Metallothionein (MT) and reduced glutathione (GSH) levels were also determined. Results demonstrate that sex has a significant influence on metal, MT and GSH concentrations. Significant maternal transfer of Pb and Zn from ovigerous females to eggs was verified, while female crabs, both ovigerous and non-ovigerous, showed elevated GSH and MT in viscera when compared to males, indicating possible MT role in excreting metals to eggs in ovigerous females of this species. Several strong statistical correlations between metals and MT indicate MTs role in detoxification of both toxic and essential elements in different organs. Pb and Zn were significantly correlated to GSH, indicating oxidative stress caused by the former and a direct link between Zn and GSH in maintaining homeostasis. Regarding human consumption, metal concentrations were lower than the maximum permissible levels established by international and Brazilian regulatory agencies, indicating that this species is safe for human consumption concerning this parameter. The presence of metals in Callinectes sp., however, is still of importance considering that this is a key species within the studied ecosystem and, therefore, plays a major role in the transference of pollutants to higher trophic levels. In addition, the presence of significant metal concentrations found in eggs must be considered in this context, since crab eggs are eaten by several other species, such as shorebirds, seabirds, and fish. Also, to the best of our knowledge, this is the first study regarding both MT and GSH levels in Callinectes sp. eggs and is of interest in the investigation of molecular mechanisms regarding metal exposure in these crustaceans. Data reported in this study support the conclusions from previous reports, provide mechanistic insights regarding metal exposure, metallothionein and oxidative stress induction in this species and also present novel data regarding eggs.