SÃrie temporal do fitoplÃncton no estuÃrio de Barra das Jangadas (JaboatÃo dos Guararapes-Pernambuco-Brasil)




The Barra das Jangadas (PE-Brazil) estuarine system, located at the South of Recife City, have been in the last years under strong anthropic impacts. This estuarine system was studied to assess the phytoplankton temporal dynamics and to obtain the main environmental factors affecting the area. Sampling was carried out in one fixed station during a temporal series (seven consecutive days) from a spring tide to a neap tide, corresponding to two diurnal cycles, at each three hours interval, in a 24 hours period. The collections were made during the dry (January 09 to 16/2001) and rainy (July 04 to 11/ 2001) seasons, by using a Van Dorn bottle and a plankton net (45μm of mesh size), being the samples preserved in lugol solution and 4% neutralized formaldehyde, respectively. Samples for chlorophyll a and hydrological parameters were obtained simultaneously. The salinity was higher during the dry season and high tides; the dissolved oxygen was higher during high tides and flood tides of the same season; and the nutrients during low tide of the rainy season. It was identified 266 taxa, outranking as dominants and those that characterized the area, the diatoms: Cyclotella meneghiniana and Coscinodiscus centralis, the bue-green algae: Microcystis flos-aquae, Microcystis aeruginosa and Oscillatoria sp.1 and the chlorophycean: Sphaerocystis sp., showing the dominance of both freshwater and marine species (49 e 48%, respectively). Fourty eight species were registered as new occurrence to Pernambuco State. The phytoplankton biomass varied from 5.91 mg.m-3 to 158 mg.m3, being higher at the dry season, with the same pattern as the phytoplanktonic density which varied from 95x103 Cel.L-1 to 7,830x103 Cel.L-1. The dry season was characterized by diatoms and phytoflagellates blooms, while the rainy season presented chlorophyceans, blue-green algae and diatoms blooms, showing to this season a temporal series variation. The results show that the Barra das Jangadas estuarine system is an euthrophic environment under strong anthropic impacts, receiving polluted load, which is causing changes in the phytoplankton community structure and in the environmental parameters. The rain fall, the tidal cycle and salinity are the main factors conditioning the hydrological parameters and phytoplankton density, and biomass


biomassa fito-planctÃnica â estuÃrio de barra das jangadas â jaboatÃo (pe) fitoplÃncton â sÃrie temporal â estuÃrio de barra das jangadas â jaboatÃo (pe) oceanografia biolÃgica â fitoplÃncton â ecologia e taxonomia hidrologia â fitoplÃncton â sÃrie temporal â estuÃrio de barra das jangadas (pe) oceanografia

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