INVESTIGADORES
PRATOLONGO paula Daniela
congresos y reuniones científicas
Título:
Long-term decreasing trend and seasonal shift in the abundance of Thalassiosira curviseriata in the Bahía Blanca Estuary
Autor/es:
GUINDER, V.; POPOVICH, C.; PRATOLONGO, P.; MARCOVECCHIO, J.; FREIJE, H.
Lugar:
Mar del Plata
Reunión:
Conferencia; CERF 2012-The changing coastal and estuarine environment: a comparative approach; 2012
Institución organizadora:
Coastal and Estuarine Research federation
Resumen:
The monitoring of phytoplankton structure and composition is an accurate tool to track environmental changes in coastal
ecosystems. We present here the long-term (1978-2008) variability in the abundance of the diatom Thalassiosira
curviseriata Takano 1981, a key phytoplankton species in the Bahía Blanca Estuary (38º45´S, 62º20´W), Argentina, in
relation to modifications in the pelagic conditions. For more than 20 years, 1978-2002, T. curviseriata was present
throughout the annual cycle and has been a recurrent blooming species in winter-early spring. The maximal densities were
always in winter (temperature range of 5-10 °C) over 1 x 106 cells L-1 (up to 12.7 x 106 cells L-1 in 1992), accounting
for 60 - 96 % of the total phytoplankton abundance. In the last years (2003, 2006-2008), the population of T. curviseriata
has significantly decreased in winter, with abundances lower than 0.8 x 106 cells L-1 in 2003 and 0.4 x 106 cells L-1
during 2006-2008. Moreover, it was not present all year-round and showed abundance peaks in spring and summer (up to
0.3 x106 cells L-1). Empirical studies of T. curviseriata isolated from the Bahía Blanca Estuary allowed characterize this
species as eurythermal (5-20 ° C) and euryhaline (25 - 40 PSU) adapted to relatively low light intensities (growth became
saturated between 70-80 μmol m-2 s-1 and inhibited at 150 μmol m-2 s-1). The modifications in water temperature,
turbidity and pelagic trophodynamics observed over the past three decades in the Bahía Blanca Estuary seem to be the
driving factors of T. curviseriata decrease and seasonal shift. We discuss potential niche modifications, ecological traits
and species-specific interactions implicated in the exclusion of T. curviseriata from the winter period in this estuarine
ecosystem.