IADO   05364
INSTITUTO ARGENTINO DE OCEANOGRAFIA
Unidad Ejecutora - UE
artículos
Título:
Role of nutrients in the phytoplankton development during a winter diatom bloom in a eutrophic South American Estuary (Bahía Blanca, Argentina)
Autor/es:
SPETTER, C.V.; POPOVICH, C.; ARIAS, A.H.; ASTEASUAIN, R.; FREIJE, R.H.; MARCOVECCHIO, J.H.
Revista:
JOURNAL OF COASTAL RESEARCH
Editorial:
COASTAL EDUCATION & RESEARCH FOUNDATION
Referencias:
Lugar: Florida; Año: 2012
ISSN:
0749-0208
Resumen:
The Bahía Blanca Estuary is considered to be highly eutrophic due to its very high nutrient concentrations. Long-term studies in this estuary have shown that the winter-early spring bloom can be considered as the development of a diatom assemblage (Thalassiosira spp. and Chaetoceros spp.) with T. curviseriata as the dominant species. From 2003 and up the present, several changes have been observed in the annual pattern of nutrients and phytoplankton. In order to assess the availability of nutrients and their relationship with phytoplankton development, nutrient variability was studied in relation to environmental conditions and phytoplankton structure during a winter bloom in 2003 (considered as a turning year). The variability of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorous (as PO43-), dissolved Silicates (DSi), chlorophyll a (Chl-a), phytoplankton abundance, particulate organic matter (POM) and physicochemical parameters were measured between April 22nd and September 4th 2003 in Cuatreros Port (inner zone of the Bahía Blanca Estuary). Besides, the dissolved nutrient concentrations in the Sauce Chico River were monthly measured to estimate the input of the river. The results of this study were compared with a previous typical winter diatom bloom (2002). In 2003, the winter diatom bloom was dominated by Cyclotella sp. (< 20 μm) and presented high Chl-a concentrations (ranges 26.5 - 40.4 μg L-1). Thalassiosira curviseriata, which was historically described as the dominant species, was presented only at three sampling dates reaching up to 19 % of the total abundance. Dissolved oxygen (DO), nitrate mean concentrations, oxygen saturation percentage (Ox.S%) and salinity mean values were significantly higher in 2003 than 2002. On the contrary, N:P ratios were significantly lower in 2003 than in 2002. Examination of nutrient ratios showed that Si was never limiting. A shift in the potential limiting nutrient between the two years (N in 2003 and P in 2002) leading to a change in species dominance during the winter blooms. Results suggest that the nutrients levels in the coastal ecosystems as Cuatreros Port play an important role in the control of phytoplankton dynamics during the productive period and partially explain its inter-annual variability.