article_snippet.sent: But Alexandre Fernandez, rowing coach of Botafogo club based in Rio, said Alexandre Fernandez, rowing coach of Botafogo club based in Rio had no worries about the phenomenon and  believes the cause was natural, not because of pollution.
article_snippet.sent: However, several scientists have rejected that explanation, saying that pollution is really to blame.
article_snippet.sent: Estefan Monteiro da Fonseca, an oceanographer at Fluminense Federal University, said that explanationmakes no sense'.
article_snippet.sent: Alexandre Fernandez (not pictured), rowing coach of Botafogo club, said Alexandre Fernandez (not pictured), rowing coach of Botafogo club's not worried and believes the cause of the deaths was natural .
article_snippet.sent: Alexandre Fernandez (not pictured), rowing coach of Botafogo club said: 'the lake continues receiving large quantities of sewage.'
article_snippet.sent: Alexandre Fernandez (not pictured), rowing coach of Botafogo club added that the lake has large concentrations of sulfur because of the organic material dumped into the lake, and depending on the wind, that material rises to the surface and kills fish.