Estrutura e produtividade da comunidade fitoplanctÃnica de um estuÃrio tropical (SirinhaÃm, Pernambuco, Brasil)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The estuary of SirinhaÃm river located in the district of SirinhaÃm, Southern of Pernambuco state, (8Â34â-8Â37âS e 35Â04â-35Â01âW), was evaluating aiming to catalog the phytoplankton community, estimating its productive capacity, the temporal spatial dynamics and the principal environmental variables that affect its composition. The samplings of the hydrologic and biologic parameters were carried out monthly, from July/05 to June/06, in three fixed points, gathering two tides stages (low tide and high tide) in different seasonal periods (dry and rainy). Data concerning abiotics variables were measured in situ: local depth, temperature and water transparency and, at the same time, samples of water was collected with Nansen oceanography bottle for the analysis of salinity, pH, dissolved oxygen, suspended particulate matter, nutrient salts and Kitahara bottle was used to chlorophyll a and phytoplankton production. The phytoplankton samples were collected with superficial horizontal hauls during 3 minutes, using plankton net (64μm mesh size) and, later, fixed with 4% buffered. The tides shows significant differences, with the salinity, water transparency, dissolved oxygen, oxygen saturation rate and pH standing out in the high tide, and nitrate, suspended particulate matter and phytoplankton biomass in the low tide. Seasonally, transparency and temperature of the water were statistically significant in the dry period and dissolved oxygen, oxygen saturation rate, nutrient salt, suspended particulate matter and biomass in the rainy period. The environment varied of limnetic to euhaline being vertically homogeneous, with some areas characteristic of polluted zone and other of supersaturate, and the biomass with the phytoplankton production characterized the environment as eutrophic. 180 taxa were found, distributed among diatoms, chlorophyceas, dinoflagelates, cyanophyceas, euglenophyceas and rodophyceas, in order of taxonomic richness and abundance, outranking as dominant and/or frequents the species Bacillaria paxillifera (O. F. MÃller) Hendey, Chaetoceros sp., Cerataulus turgidus Ehrenberg, Coscinodiscus oculus-iridis Ehrenberg, Terpsinoe musica Ehrenberg, Synedra sp., Oedogonium sp. e Pleodorina sp. The taxonomic richness do not showed seasonal variation, observing spatial variations. The presence of eurihaline marine species was significant (42,47%), followed by the oligohaline (25,34%) and estuarine (7,53%). The principal components analysis shows that the tide stages and salinity contributed to the environmental complexity, being the main variables controlling the hydrologic parameters and the distribution of phytoplankton composition. The specific diversity, which the values were considered high (>2,5) in most of the samples, demonstrated a homogeneous distribution of the populations and a heterogeneity strongly affected by the freshwater and marine inputs. The data of environmental variables relative of water quality (dissolved oxygen and nutritents), of the biological parameters (composition, biomass and phytoplankton production) besides the specific diversity index confirmed that the studied area is under impacts, that are minimized by the tide stages.

ASSUNTO(S)

pluviometry oceanografia biomassa fitoplanctÃnica microalgas phytoplankton biomass phytoplankton hydrology specific diversity taxonomy hidrologia microalgae fitoplÃncton pluviometria oceanografia

ACESSO AO ARTIGO

Documentos Relacionados