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Aquatic food chain: Otter
(Lontra longicaudis), an exploratory research with mercury (Hg).
The aim of this research was to evaluate
the total mercury (Hg) concentrations in otters (L.longicaudis) from different locations. To reach for these goals otter feaces
(spraints) were collected in July, 2004, January, 2005
and May, 2005 at Barra Bonita and Bariri reservoirs, SP. The spraints were used, not only to
identify the animal food intake, but also to analyze the concentration of total
Hg. In addition, fur samples from these reservoirs, as well as from the Piracicaba river, the Fundação Parque Zoológico de São
Paulo (São Paulo Zoo), from two dead animals found in the State of Bahia, and from a fur originated from a mining area in
the Crixas river, Goiás
State were also analyzed.
The results indicated that otter’s spraints collected at the Barra Bonita
reservoir presented 100,52 ng.g-1 medium Hg contents, in January, and 177,45
ng.g-1 in May, 2005. At Bariri reservoir, the medium
Hg concentrations were 55,97 ng.g-1 in July, 2004 and 243,2 ng.g-1 in May, 2005. Analyzing theses same samples,
considering the food intake, a great amount of Cichlidae fish family, followed
by the Serrasalmidae fish family were identified. It were observed that high
total Hg concentration in spraints were associated with scale frequency of
fishes from the Serrasalmidae family found in the spraints. The analyses of the
fur collected in the Barra Bonita and Bariri reservoirs showed that Hg
concentration varied from 0.02 to 1.02 μg.g-1; in Piracicaba river, the total concentration
was of 0.55 μg.g-1; at the gold mining area located at rio Crixás presented medium
levels of 7.25 μg.g-1 and samples fur from Bahia presented 8.56 μg.g-1medium
levels. Both, otter feaces and fur samples were acid digested in a mixture of
HNO3:H2SO4:HClO4, in an open system, being the sample detection made by atomic
fluorescence specthrometry. Accuracy was assessed by two Certified Reference
Materials, DORM-2 and BCR-414, with good recovery percentage in both cases.
Study site at Bariri Reserve, São Paulo state
Spraints were cleaned up in the field, eliminating the sand
grains adhere to the sample
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