INVESTIGADORES
SPINELLI Mariela Lorena
congresos y reuniones científicas
Título:
Annual changes in distribution and abundance of appendicularians off the La Plata River estuary, SW Atlantic Ocean
Autor/es:
MARIELA L. SPINELLI; PATRICIA MARTOS; FABIANA L. CAPITANIO; MARCELO PAJARO; MARÍA DELIA VIÑAS; GRACIELA ESNAL
Lugar:
Bahia Blanca, Argentina
Reunión:
Simposio; Science and management of estuaries and coasts: A tale of two hemispheres; 2008
Institución organizadora:
The Estuarine and Coastal Sciences Association (ECSA) y el Instituto Argentino de Oceanografía (IADO)
Resumen:
Among tunicates, the small planktonic appendicularians generally comprise a significant fraction of the mesozooplankton of estuarial environments. The interannual variability of the species composition and abundance as well as their salinity preferences were studied during three spring cruises (2002-2004) carried out off the La Plata River as a part of INIDEP Pelagic Fishery Programmes. Approximately 75 samples were collected in each cruise with a Pairovet net (200 µm mesh size) trawled vertically through the water column and CTD data profiles were recorded simultaneously. The river’s outflow varied between years. Surface salinity distribution showed that during 2002 the river discharged to the east and north but, afterwards, the outflow was directed only to the east. Salinity legs (0-80 m) showed, mainly in coastal stations, the presence of stratified waters up to 37°S. Three appendicularian species were found: Oikopleura dioica, O. fusiformis and Fritillaria borealis, being O. dioica the dominant one. The highest abundances were detected in the frontal area (2628 ind.m-3) during 2002. The species salinity preferences were calculated using a Kolmogorov-Smirnov test grouping salinity data in classes. Oikopleura dioica evidenced a significant association (p<0,05) between abundance and salinity (Dmax= 14,31) during 2002, however, no association was detected in the other years. F. borealis and O. fusiformis were associated to mid-shelf waters, south and north of the estuarine area, respectively, being most abundant in 2003.