Genetic Diversity of Lepilemur mustelinus ruficaudatus, a Nocturnal Lemur of Madagascar

The genetic polymorphism of natural populations of Lepilemur mustelinus ruficaudatus was studied by protein electrophoresis. We sampled blood from 72 individuals from four populations separated by geographic or anthropogenic barriers from southwestern Madagascar. Six out of 22 enzyme loci showed genetic variation with a degree of polymorphism of 0.273. The expected and observed degree of genetic heterozygosity over all loci is similar to that of other primates (H_e = 0.058, H_o = 0.036). The F-statistics revealed that the four subpopulations were similar with respect to gene structure (F_ST = 0.065, p = 0.016), but the genotypic structures within subpopulations were inconsistent with random mating. For the total of the four subpopulations the proportion of heterozygous individuals was significantly smaller than expected under random mating (F_IS = 0.373, F_IT = 0.414, p < 0.01). These results correspond closely to what is expected considering the low migration ability of individuals of L. m ruficaudatus leading to small and rather isolated inbred populations.     

Mercury accumulation in sediment and fish from rivers affected by alluvial gold mining in the Brazilian Madeira River basin,Amazon

The degree and distribution of mercury (Hg) accumulation in sediment and fish from a tributary affected by alluvial small-scale gold mining in the Madeira River/Amazon is studied, in relation to a reference site. The results obtained so far agree well with previous studies and confirm that a tremendous contamination of main food web compartments occurs in these highly exposed, but vulnerable tropical waters. An essential part of the released metallic Hg may still exist as macroscopic liquid Hg drops in the sediment. Both global (0.4 mg/kg of Hg) and local (0.1 mg/kg of Hg) background sediment values as well as safety levels for fish (0.5 mg/kg of Hg) are considerably exceeded by a factor of up to 25, 100, and 4, respectively, and give rise to serious concern, not least with regard to the formation of the very toxic monomethyl-Hg. It is further discussed that atmospheric transport and deposition of Hg in water reservoirs built for hydroelectric power generation may act as critical pathways for longterm Hg accumulation, even in unexposed riverine systems.