Total mercury concentration in the fur of free-ranging giant otters in a large Neotropical floodplain.

The giant otter, Pteronura brasiliensis, (Zimmermann, 1780), is a semiaquatic carnivore that feeds mainly on fish. Mercury has high toxicity and high potential for bioaccumulation in tissues and biomagnification in organisms through food chains. Thus, as a top predator in the trophic chain, the giant otter has the potential to accumulate mercury by biomagnification. The objective of the present study was to measure the total mercury concentration in giant otter fur samples from an area in the southern Brazilian Pantanal. Fur samples from 19 otters from different social groups were collected from captured animals or were sampled with biopsy darts. Total mercury determination was performed by cold steam spectrophotometry. Mercury concentrations found in the giant otter fur were 7.15 ± 3.41 µg g-1 (2.01-12.06 µg g-1) dry weight. The values are above to the upper limit found in fur samples of otter species not exposed to contamination sources, which typically range from 1 to 5 µg g-1. The concentrations found in the study area indicate that even in the southern Pantanal, which is approximately 475 km from gold mining activity, mercury can be considered a threat for giant otters, as well as for riverside populations. It is also important to consider that other anthropogenic sources of mercury, such as pesticides used in agriculture, could affect this population.

Diet of Lontra longicaudis (Carnivora: Mustelidae) in a pool system in Atlantic Forest of Minas Gerais State, southeastern Brazil - doi: 10.4025/actascibiolsci.v34i4.10332

The present study aimed to investigate the feeding habits of Lontra longicaudis in a pool system within the Private Reserve of Natural Patrimony (RPPN) Usina Maurício, located in Paraíba do Sul river basin, Atlantic Forest of southeastern Minas Gerais State. The diet composition was determined based on the identification of items present in 212 scats sampled between July 2008 and October 2009 in a 4.1 km stretch of the pool system. The found items and its respective percentages of occurrence were: mollusks (0.5%), insects (16.5%), spiders (1.4%), crustaceans (3.3%), fish (96.7%), amphibians (0.9%), snakes (3.8%), birds (2.8%), mammals (8.5%) and fruits (0.5%). Among fish, the identified families and respective percentages of occurrence were: Loricariidae (65.4%), Pimelodidae (42.9%) Cichlidae (22%), Characidae (7.3%), Erythrinidae (3.9%), Synbranchidae (2.4%), Anostomidae (2%). Therefore fish make up the most consumed item in the study area, with the predominance of benthic siluriformes (families Loricariidae and Pimelodidae).