ABSTRACT - (Contents of lignins, nitrogen and tannins in leaves of typical species of mangroves). The contents of lignins, total N and tannins were measured in leaves of Avicennia schaueriana, Laguncularia racemosa and Rhizophora mangle. The leaves were collected in mangrove areas of Suape, Madre de Deus island (a highly polluted site in Bahia), Cananéia and two localities of Bertioga, one of them with high levels of pollution, in which no individuals of Rhizophora occur, and the other being an area adjacent to the latter. The leaves of Laguncularia and Rhizophora contain high contents of tannins, the former presenting from three to four times as much tannins as the latter. Leaves of Avicennia are devoid of tannins and possess the highest contents of N. The contents of lignins increase in general along the sequence Avicennia<Laguncularia<Rhizophora. The contents of N, for all species, were practically the same, comparing the samples from Suape and Cananéia. However, the leaves from Bertioga presented higher levels, which reached a maximum in samples from the most polluted area. The leaves of Laguncularia and Rhizophora collected in Suape presented less tannins and more lignins than the samples from Cananéia. The contents of tannins of the leaves of Laguncularia were higher in the samples of Bertioga than those of Cananéia, but the opposite is observed in Rhizophora. The amount of tannins in leaves of Laguncularia from Madre de Deus were the lowest among the localities investigated. The contents of lignins seem to be strongly influenced by pollution, a regular decrease being observed along the series Cananéia>Bertioga/adjacent area>Bertioga/polluted area. It seems that the levels of N and lignins are affected by pollution, the former assuming higher values in polluted areas and the latter lower values. The leaves of Laguncularia from Madre de Deus presented also relatively low levels of lignins, probably as a consequence of environmental impact. A possibility is raised that a decrease in the production of lignins may be one of the reasons for the replacement of Rhizophora by Laguncularia in the most polluted areas.
Mangrove; Avicennia; Laguncularia; Rhizophora; tannins; lignins
