%0 Journal Article
%T Temporal variability of chlorophyll-a in the S o Vicente estuary
%A Andr¨¦ Francisco Bucci
%A ¨¢urea Maria Ciotti
%A Ricardo Cesar Gon£¿alves Pollery
%A Renan de Carvalho
%J Brazilian Journal of Oceanography
%D 2012
%I Universidade de S?o Paulo
%X Estuaries are extremely dynamic environments that are vulnerable to anthropogenic alterations. Thus, monitoring phytoplankton abundances and composition is an essential tool for the prediction of eutrophication and its effects on coastal ecosystems. Phytoplankton biomass, as chlorophyll-a, in the S o Vicente estuary (Brazil) varies in response to tidal cycles and seasonal rainfall. Objectives. To present two datasets designed to assess the relationship between chlorophyll-a and changes in water turbidity driven by tide and rain. Methods. Weekly observations were made in the shallow embayment (February to September 2008; site 1) and observations recorded on alternate days (summer 2010, site 2). Results. At site 1, turbidity differed between high and low tides, but on most days was over 3000 RU, maintaining moderate chlorophyll-a levels (4 mg.m-3) and only two blooms developed during low turbidity. Site 2 mean turbidity was 1500 RU, nutrient level was higher during neap tides and phytoplankton blooms were mainly observed at the end of neap tides at 15-day intervals, dominated by chain-forming diatoms and occasionally flagellates and pennate diatoms. Conclusions. Taxonomic composition of the blooms was different and their frequency altered by events characterized by intense freshwater discharges from the Henry Borden Hydroelectric Dam (> 9*106.m3), inhibiting phytoplankton accumulation during neap tide periods. Estu¨¢rios s o ambientes dinamicos e suscept¨ªveis a altera  es antropog¨ºnicas. Nesses ambientes, torna-se imprescind¨ªvel monitoramento do fitoplancton na previs o da eutrofiza  o e de seus efeitos para o ecossistema. No estu¨¢rio de S o Vicente (Brasil) a biomassa fitoplanct nica, como clorofila-a, varia sazonalmente em resposta ¨¤s chuvas e mar¨¦s. O presente estudo visa apresentar dois programas de monitoramento para detectar flora  es fitoplanct nicas em rela  o a turbidez da ¨¢gua guiada pelas mar¨¦s e chuvas. M¨¦todos. As observa  es foram semanais na por  o rasa (Fevereiro a Setembro de 2008; ¨¢rea 1) e observa  es em dias alternados no canal (ver o de 2010; ¨¢rea 2). Os resultados mostram que a ¨¢rea 1, turbidez acima de 3000 RU manteve n¨ªveis de clorofila-a m¨¦dios (4 mg.m-3) e duas flora  es ocorreram apenas em baixa turbidez, sendo esta diferente entre mar¨¦s alta e baixa. Na ¨¢rea 2, a turbidez manteve-se entre 1500 RU, os nutrientes foram maiores durante as mar¨¦s de quadratura, e as flora  es tiveram frequ¨ºncia de aproximadamente 15 dias, no final da quadratura, predominando diatom¨¢ceas em cadeia e eventualmente flagelados e diatom¨¢ceas penadas. A co
%K Padr es temporais
%K Descarga de ¨¢gua doce
%K Biomassa fitoplanct nica
%K Estu¨¢rios controlados por mar¨¦
%K Temporal pattern
%K Freshwater runoff
%K Phytoplankton biomass
%K Tide regulated estuaries
%U http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-87592012000400007