Dissolved Nutrient Availability during Winter Diatom Bloom

CECILIA POPOVICH; CARLA SPETTER; JORGE MARCOVECCHIO; HUGO FREIJE,

JOURNAL OF COASTAL RESEARCH

Coastal Education & Research Foundation, Inc.

Lugar: Palm West, Florida, USA.; Año: 2008 vol. 24 p. 95 - 102

0749-0208

POPOVICH, C.A.; SPETTER, C.V.; MARCOVECCHIO, J.E., and FREIJE, R.H., 2007. Dissolved nutrient availability during winter diatom bloom in a turbid and shallow estuary (Bahý´a Blanca, Argentina). Journal of Coastal Research,Journal of Coastal Research, 00(0), 000–000. West Palm Beach (Florida), ISSN 0749-0208. The inner zone of Bahý´a Blanca Estuary is a shallow, well-mixed, highly turbid, and nutrient-rich temperate ecosystem. The phytoplankton annual cycle is characterized by a recurrent winter/early-spring diatom bloom. From May to August 2002 a research program aimed to describe the potential relations between the dynamics of phytoplankton and nutrients was carried out. Phytoplankton composition, abundance, chlorophyll a (Chl a), and dissolved inorganic nutrients (DIN: nitrate, nitrite, ammonium, phosphate, and silicate) were measured. The species involved were classified in blooming (including Thalassiosira spp. and Chaetoceros spp.) and nonblooming species (including other diatoms and dinoflagellates). The results show: (1) a prebloom period, which includes low biomass values and a strong decrease of NO ; (2) an and dinoflagellates). The results show: (1) a prebloom period, which includes low biomass values and a strong decrease of NO ; (2) an nutrients (DIN: nitrate, nitrite, ammonium, phosphate, and silicate) were measured. The species involved were classified in blooming (including Thalassiosira spp. and Chaetoceros spp.) and nonblooming species (including other diatoms and dinoflagellates). The results show: (1) a prebloom period, which includes low biomass values and a strong decrease of NO ; (2) an and dinoflagellates). The results show: (1) a prebloom period, which includes low biomass values and a strong decrease of NO ; (2) an a (Chl a), and dissolved inorganic nutrients (DIN: nitrate, nitrite, ammonium, phosphate, and silicate) were measured. The species involved were classified in blooming (including Thalassiosira spp. and Chaetoceros spp.) and nonblooming species (including other diatoms and dinoflagellates). The results show: (1) a prebloom period, which includes low biomass values and a strong decrease of NO ; (2) an and dinoflagellates). The results show: (1) a prebloom period, which includes low biomass values and a strong decrease of NO ; (2) an Thalassiosira spp. and Chaetoceros spp.) and nonblooming species (including other diatoms and dinoflagellates). The results show: (1) a prebloom period, which includes low biomass values and a strong decrease of NO ; (2) an 3 initial bloom period characterized by high diatom abundance and Chl a, a marked dominance of Thalassiosira curviseriata,a, a marked dominance of Thalassiosira curviseriata, and a strong decrease of NH ; (3) an intermediate bloom period of high abundance, codominance of blooming  4 species, and a strong decrease of PO3; and (4) a final bloom period with a decrease in abundance of blooming species3; and (4) a final bloom period with a decrease in abundance of blooming species 4 and a general nutrient recovery. Thalassiosira curviseriata seems to be a species associated with high nutrient stock and low light intensity. Its growth, mainly concurrent with DIN decrease, was related to new production in this area. The obtained data suggest that low phosphate concentrations, more than DIN and silicates, contributed to the diatom bloom collapse. According to our results, this high production during winter can be explained as a net growth of phytoplankton because of a successful low light- and temperature-acclimated species, possibly favored by low predation and high nutrient availability. and low light intensity. Its growth, mainly concurrent with DIN decrease, was related to new production in this area. The obtained data suggest that low phosphate concentrations, more than DIN and silicates, contributed to the diatom bloom collapse. According to our results, this high production during winter can be explained as a net growth of phytoplankton because of a successful low light- and temperature-acclimated species, possibly favored by low predation and high nutrient availability. Thalassiosira curviseriata seems to be a species associated with high nutrient stock and low light intensity. Its growth, mainly concurrent with DIN decrease, was related to new production in this area. The obtained data suggest that low phosphate concentrations, more than DIN and silicates, contributed to the diatom bloom collapse. According to our results, this high production during winter can be explained as a net growth of phytoplankton because of a successful low light- and temperature-acclimated species, possibly favored by low predation and high nutrient availability.