IADO   05364
INSTITUTO ARGENTINO DE OCEANOGRAFIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Zooplankton seasonal changes in a Southwestern Atlantic temperate estuary (Bahía Blanca, Argentina).
Autor/es:
MELISA FERNANDEZ SEVERINI; ANABELLA BERAZATEGUI; MONICA HOFFMEYER; JORGE MARCOVECCHIO
Lugar:
Kiel
Reunión:
Congreso; AQUASHIFT: Life in warming waters; 2010
Institución organizadora:
Christian Albrecht’s University, Kiel (Germany)
Resumen:
In this work we analyzed the seasonal dynamics of Acartia tonsa and Eurytemora americana, two key copepod species of the zooplankton of the Bahía Blanca estuary, Argentina. Information from 2005 to 2007 was compare with historical data (1980-2000) in order to detect possible changes in their seasonal dynamics. Based on historical data, the zooplankton of the Bahia Blanca estuary has been characterized by marked seasonal variations. A. tonsa has largely dominated the mesozooplankton community during most of the year, while E. americana has been the dominant species only during spring. From December (summer) to April (early autumn), the population of the former reaches the maximal abundances, while during winter and spring it shows the minimum. On the other hand, E. americana has been the domimant species from June to October (late winter-spring). The population of this species is closely related to the phytoplankton bloom, which also occurs during this period. As an herbivore copepod, E. americana feeds on primary producers. The decrease of the abundance of A. tonsa over this period seems to be linked to the coexistence with its food competitor: E. americana. When the algal bloom decreases, the population of E. americana disappears, suggesting a strongly relationship with food availability. In recent years, 2005-2007 some variations on this pattern have been observed. E. americana has dramatically increased its abundance in 2007. In addition, comparisons with historical information seem to indicate that the population of E. americana is increasing. Regarding A. tonsa, some differences in the annual pattern have also been observed. We believed that the shifts on zooplankton seasonality are linked to changes in both temperature and phytoplankton due to their strong dependence on these variables. However the present work is the starting point and further studies are necessary to attempt this issue. In this sense, several biological and physico-chemical studies are being carried out in order to explain these modifications.