Background: The Present study was carried out to track and calculate Biomagnification

Top marine predators present high mercury concentrations in their tissues as consequence of biomagnification of the most toxic form of this metal, methylmercury (MeHg). The present study concerns mercury accumulation by Guiana dolphins (Sotalia guianensis), highlighting the selenium-mediated methylmercury detoxification process. Liver samples from 19 dolphins incidentally captured within Guanabara Bay (Rio de Janeiro State, Brazil) from 1994 to 2006 were analyzed for total mercury (THg), methylmercury (MeHg), total organic mercury (TOrgHg) and selenium (Se). X-ray microanalyses were also performed. The specimens, including from fetuses to 30-year-old dolphins, comprising 8 females and 11 males, presented high THg (0.53–132 µg/g wet wt.) and Se concentrations (0.17–74.8 µg/g wet wt.). Correlations between THg, MeHg, TOrgHg and Se were verified with age (p<0.05), as well as a high and positive correlation was observed between molar concentrations of Hg and Se (p<0.05). Negative correlations were observed between THg and the percentage of MeHg contribution to THg (p<0.05), which represents a consequence of the selenium-mediated methylmercury detoxification process. Accumulation of Se-Hg amorphous crystals in Kupffer Cells was demonstrated through ultra-structural analysis, which shows that Guiana dolphin is capable of carrying out the demethylation process via mercury selenide formation.

Despite the magnitude of domestic and industrial pollution, fishery yield registered in several landing points at

To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ13C and δ15N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ13C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ13C value, while oceanic species showed significantly lower δ13C values. The highest δ15N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ15N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ13C values, but similar δ15N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ13C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area.

The Amazon's reputation and ability to draw tourists is strongly associated with the natural environment and with tourist's ability to sight and interact with iconic animals. In Brazil, four cases of aggregations of wild boto (Amazon River dolphin; Inia geoffrensis), becoming conditioned to human contact through food provisioning are occurring in Amazonas State, Central Amazon, where tourists can feed, touch and swim with the botos. The feeding of wild dolphins imposes significant risks, both for the dolphins and for the tourists, and these dangers are evident at Novo Airão City, which is the longest established of the four mentioned cases. There are few rules imposed, inadequate infrastructure and no specialized employee training or surveillance. Competitive, aggressive interactions between dolphins, pushing, ramming and biting are common and a number of dangerous interactions between the dolphins and tourists have been observed. It is evident that the establishment of this tourist-dolphin interaction is facilitated by the deliberate feeding of the dolphins and that this activity has become financially lucrative for local people. Despite bringing benefits to the region, the growth of this 'botos feeding tourism' activity in the Amazon is currently poorly managed and there is a high risk of injury or fatality if interactions continue to develop without improved and careful management. Additional key words: swim-with-dolphins, Amazon, wildlife management. Resumo (O crescimento do "turismo de alimentação de botos", uma nova indústria de turismo baseada no boto da Amazônia, Inia geoffrensis, no Estado do Amazonas, Brasil)-Na Amazônia, a habilidade e tradição de atrair turistas estão fortemente associadas ao ambiente natural e à oferta turística de observação e interação com animais icônicos. No Brasil, quatro casos de agregações de botos da Amazônia (também chamado de boto-vermelho ou boto-cor-de-rosa; Inia geoffrensis) condicionados ao contato humano através da alimentação deliberada vêm ocorrendo no Estado do Amazonas, na Amazônia Central, onde os turistas podem alimentar, tocar e nadar com os botos. A alimentação de golfinhos selvagens implica significantes riscos, tanto para os animais como para os turistas, e esses riscos são evidentes na cidade de Novo Airão, que é o mais antigo dos quatro casos mencionados. Existe pouca regulamentação, infraestrutura inadequada e ausência de profissionais especializados para monitorar as atividades. Interações competitivas e agressivas, empurrões, investidas e mordidas são comuns entre os botos, assim como interações de risco entre os turistas e os animais. É evidente que o estabelecimento dessa interação homem-golfinho é facilitado pela alimentação deliberada e que a atividade se tornou financeiramente lucrativa para a população local. É também claro que essa é uma atividade repleta de riscos, tanto para os botos como para os turistas. Apesar de trazer benefícios para a região, o crescimento desse 'turismo de alimentação de botos' na Amazônia é atualmente mal manejado e exis...