2014-03-252014-03-252012-12MATOS, Jislene Brito et al. Caracterização quali-quantitativa do fitoplâncton da zona de arrebentação de uma praia amazônica. Acta Botanica Brasilica, online, v. 26, n. 4, p. 979-990, out./dez. 2012. DOI: http://dx.doi.org/10.1590/S0102-33062012000400028. Disponível em: http://repositorio.ufpa.br/jspui/handle/2011/4832. Acesso em:.0102-3306https://repositorio.ufpa.br/handle/2011/4832The structure of the phytoplankton community of Princesa beach (Maiandeua island) was investigated during a nyctemeral cycle in the months of November/08, March/09, June/09 and September/09 to verify the effects of certain environmental variables on this community. The microphytoplankton of Princesa beach was represented by 98 taxa with the dominance of the diatoms, which were followed by the dinoflagellates and cyanophytes. The qualitative study revealed that Coscinodiscus perforatus Ehrenberg was abundant in March (45.6%) and June (45.1%), whereas in the quantitative analysis Dimeregramma minor (Gregory) Ralfs was dominant, mainly in November/08 (82.0%) and September/09 (83.0%). Biomass (chlorophyll-a content) was significantly higher in March/08 (U= 0.0; p <0.05). The average total phytoplankton density was significantly higher during the rainy period (F= 6.2; p< 0.05), mainly in June (1,223 ±110 x 103 cell L-1). K-dominance curves showed a gradual decrease in diversity along the dry period. Non-Metric MulAcesso AbertoPlânctonVariáveis ambientaisLitoral AmazônicoPlanktonEnvironmental variablesAmazon littoralArtigo de Periódico10.1590/S0102-33062012000400028