Phytoplankton community in a tropical estuarine gradient after an exceptional harmful bloom of Akashiwo sanguinea (Dinophyceae) in the Todos os Santos Bay

The objective of this study was to evaluate variations in the composition and abundance phytoplankton community after an exceptional harmful bloom Akashiwo sanguinea that occurred Todos os Santos Bay (BTS) early March, 2007. Samples were collected every ten days, between April, 2007 2008, from estuarine gradient Paraguaçu River BTS. physical chemical variables measured situ using a multiparameter sensor. Water samples for analysis dissolved inorganic nutrient concentrations microphytoplankton. Overall, 135 taxa identified, with higher richness diatoms. total cell density ranged 2.92 × 103 1.16 107 (5.47 105 ± 1.69 106) cells L−1, values freshwater zone than marine area. Five species showed peaks throughout study, forming small blooms. Four these blooms rainy season, formed by Guinardia striata (April, 2007), Scrippsiella cf. acuminata (August, Euglena gracilis Skeletonema costatum (September, while new during dry season (December, 2007). environment typically oligotrophic, low spatiotemporal variation nutrients. Even so, we observed short-term structure community, demonstrated rapid events, followed increase microphytoplankton, especially season. did not cause any notable changes water column present effects on system.