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Volume 44 - Number 1 - 2009
Article

 

Hydrobiological time series in a tropical estuary (Brazil)

Carlos E. Noriega1,2, Katia Muniz1,2, Manuel J. Flores-Montes1,2, Silvio J. Macêdo1,2, Moacyr Araujo1,3, Fernando A. Feitosa1,4 y Sirleys R. Lacerda1,4

 

1Departamento de Oceanografia, Universidade Federal de Pernambuco. Avenida Arquitetura s/n, Cidade Universitária, CEP: 50670-901, Recife, Brasil

2Laboratorio de Oceanografia Química, Universidade Federal de Pernambuco. Avenida Arquitetura s/n, Cidade Universitária, CEP: 50670-901, Recife, Brasil

3Laboratorio de Oceanografia Física, Universidade Federal de Pernambuco. Avenida Arquitetura s/n, Cidade Universitária, CEP: 50670-901, Recife, Brasil

4Laboratorio de Fitoplancton, Universidade Federal de Pernambuco. Avenida Arquitetura s/n, Cidade Universitária, CEP: 50670-901, Recife, Brasil

 

E-mail: carlos.delnor@gmail.com

 

This paper presents a hydrobiological time series at Barra de Jangadas estuary in Northeastern Brazil. Studies were carried out during seven consecutive days from a spring to a neap tide, in one fixed station during the dry (January) and rainy (July) seasons, in 2001. The meteorology (rainfall, evaporation, wind intensity), hydrology (temperature, salinity, pH, dissolved oxygen-DO and relative saturation, BOD5, nutrients (NH3+NH4, NO2-, NO3-, PO4-3, SiO2)), bathymetry, current intensity and, chlorophyll-a, were studied. The principal component analysis (PCA) explained 80% of the total variance showing an inverse relationship between nutrients and DO, salinity and pH. This analysis showed a positive correlation between low tide and nutrients, indicating anthropogenic pollution. The water temperature presented low seasonal variation, similar to chlorophyll-a, which presented values over 20 mg m-3, characterizing a eutrophic environment. Higher salt concentrations were registered during the dry season with no vertical stratification. DO varied significantly in both seasons. Total dissolved inorganic nitrogen and dissolved inorganic Phosphorus values in July were in general 2 to 5 times higher than values registered in January, respectively. The average N/P ratio varied from 35:1 in January to 8:1 in July, being both phosphate and nitrogen limiting for phytoplankton growth. Night/day differences showed that in January, ammonia decreased in higher proportion than the other nitrogen compounds indicating assimilation by the autotrophic organisms during the day

 

Key words: Nutrients, dissolved oxygen, Barra de Jangadas, eutrophication

 

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