2014-03-252014-03-252008-09SOUSA, Eliane Brabo de et al. Microfitoplâncton de águas costeiras amazônicas: Ilha Canela (Bragança, PA, Brasil). Acta Botanica Brasilica, online, v. 22, n. 3, p. 626-636, jul./set. 2008. DOI: http://dx.doi.org/10.1590/S0102-33062008000300004. Disponível em: http://repositorio.ufpa.br/jspui/handle/2011/4831. Acesso em:.0102-3306https://repositorio.ufpa.br/handle/2011/4831Seasonal and nyctemeral variations of the microphytoplankton were studied at a fixed station (00º46'37.2''S-046º43'24.5''W) on Canela Island (North Brazil) in September and December/2004 (dry season) and in March and June/2005 (rainy season). Samples for qualitative phytoplankton studies were obtained by filtering 400 L of surface water in the surf zone of the island through plankton nets (65 μm mesh size). Field work was carried out during spring tides and samples were collected every 3 hours during a 24-hour period. The collected material was fixed in neutral formaldehyde at 4%. Simultaneously, salinity of the water surface was also measured. Salinity showed significant variation throughout the study period, ranging from 26.1 (June/2005) to 39.0 (December/2004), characterizing the environment as euhaline-polyhaline. A total of 130 taxa were identified, belonging to Cyanophyta (two taxa), Bacillariophyta (115 taxa) and Dinophyta (13 taxa). Diatoms were the dominant group of microphytoplankton at Canela IslanAcesso AbertoMicroplanctonVariação sazonalFitoplânctonBiomassaDensidadeIlha Canela - PABragança - PAPará - EstadoAmazônia brasileiraArtigo de Periódico10.1590/S0102-33062008000300004