Series temporales de variables hidrobiológicas en un estuario tropical (Brasil)

Abstract

Abstract.-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, BOD 5 , nutrients (NH 3 + NH 4 , NO 2 -, NO 3 -, PO 4 -3 , SiO 2 )), 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. , SiO 2 )), batimetría, intensidad de las corrientes y clorofila-a. El análisis de componentes principales (ACP), explicó el 80% de la varianza total, mostrando una relación inversa entre nutrientes y OD, salinidad y pH. Este análisis mostró una correlación positiva entre la bajamar y los nutrientes, indicativo de polución de origen antropogénica. La temperatura del agua varió poco estacionalmente, similar a la clorofila-a que caracterizó un ambiente eutrófico con valores superiores a 20 mg m -3 . Mayores concentraciones de sal ocurrieron en el mes estival y sin mostrar estratificación vertical. El oxígeno disuelto varió significativamente entre ambos períodos. Los valores totales de nitrógeno y fósforo inorgánico disuelto en julio fueron en promedio 2 y 5 veces superiores a los de enero, respectivamente. Las medias de N:P variaron de 35:1 en enero a 8:1 en julio, siendo ambos, el fosfato y el nitrógeno limitantes para el crecimiento del fitoplancton. Diferencias día/noche evidenciaron que, en enero, el amonio decreció en mayor proporción que el resto de los compuestos nitrogenados, indicativo de la asimilación por los organismos autotróficos durante el día.Palabras clave: Nutrientes, oxígeno disuelto, Barra de Jangadas, eutroficación

Caracterização de uma zona costeira tropical (Ipojuca-Pernambuco-Brasil): Produtividade fitoplanctônica e outras variáveis ambientais.

“…De acordo com Noriega et al (2009) as análises estatísticas determinaram diferenças significativas entre os períodos estudados (estiagem e chuvoso) demonstrando a grande influência e variabilidades da maré e descarga fluvial nos processos estuarinos tropicais.…”

Nutrient budgets (C, N and P) and trophic dynamicsof a Brazilian tropical estuary: Barra das Jangadas

“…These basins cover semi-arid areas until they reach regions of intense urbanization along the coast, where they receive domestic and industrial effluents without previous treatment (CPRH 2003) (Noriega et al 2009). Both rivers suffer the impact of domestic and agricultural effluents, mainly from the sugarcane agro-industry, under the form of high Biochemical Oxygen Demand (BOD), especially between November and March (dry season).…”

“…BJE is a small estuarine area in which these rivers converge (8.7 • S-8.8 • S and 34.4 • W-34.8 • W). The estuary extends for approximately 13 km 2 , with an average depth of 2.6 m (Branco 2002, Noriega et al 2009 (Fig. 1).…”

“…The tidal regime is semidiurnal, with a mean amplitude of 1.3 m (neap tides) and 1.8 m (spring tides) (Araujo et al 1999). The estuary is well mixed, being classified as type 1 with an absence of vertical stratification (Araujo et al 1999, Noriega et al 2009). …”

Caracterización de los flujos de CO2 y los parámetros asociados con el sistema de carbonato en el estuario Río Formoso, Brasil

“…La amplitud estadística entre los promedios estivales y de invierno fue 0,7ºC. Esta variación es inferior a la observada para otros sistemas estuarinos próximos (1,5ºC) (Noriega et al 2009(Noriega et al , 2015. Sin embargo, esta amplitud es similar a la observada por Da Silva et al (2004) (1,0ºC).…”