A Tropical Estuary Where Mercury Does Not Biomagnify and its Adjacent Waters that Render Extremely High Mercury Concentrations in Top Predators.

In general, mercury (Hg) undergoes biomagnification in aquatic systems. The absence of Hg biomagnification in a certain aquatic environment constitutes an exceptional finding and this seems to be the case for Sepetiba Bay, in Rio de Janeiro state (RJ), Brazil. There are three distinct ecological populations of Guiana dolphins in the Sepetiba Bay (SB)-Ilha Grande Bay (IGB) Complex, inhabiting: (1) the inner part of SB; (2) SB entrance; and (3) IGB.

Diversity of mitochondrial DNA in 3 species of great whales before and after modern whaling.

The 20th century commercial whaling industry severely reduced populations of great whales throughout the Southern Hemisphere. The effect of this exploitation on genetic diversity and population structure remains largely undescribed. Here, we compare pre- and post-whaling diversity of mitochondrial DNA (mtDNA) control region sequences for 3 great whales in the South Atlantic, such as the blue, humpback, and fin whale.

Effective population size and the genetic consequences of commercial whaling on the humpback whales (Megaptera novaeangliae) from Southwestern Atlantic Ocean.

Genotypes of 10 microsatellite loci of 420 humpback whales from the Southwestern Atlantic Ocean population were used to estimate for the first time its contemporary effective (Ne) and census (Nc) population sizes and to test the genetic effect of commercial whaling. The results are in agreement with our previous studies that found high genetic diversity for this breeding population. Using an approximate Bayesian computation approach, the scenario of constant Ne was significantly supported over scenarios with moderate to strong size changes during the commercial whaling period.

Microsatellite genetic characterization of the humpback whale (Megaptera novaeangliae) breeding ground off Brazil (breeding stock A).

The Southwestern Atlantic Ocean humpback whales wintering ground (breeding stock A) are distributed along the Brazilian coast (5-23 degrees S), and their main mating and calving ground is in the Abrolhos Bank. We investigated genetic diversity, population structure, and relatedness of individuals sampled from the entire Southwest Atlantic humpback whale population. A total of 275 individuals sampled from 2 subregions (Abrolhos Bank, n = 229 and Praia do Forte, n = 46) were screened for 9 microsatellite loci.