Comparative analisys of the distribution of familier Salpidae and Doliolidae in relation to total zooplankton on the southeastern continental shelf of Brazil by means of semi-automatic techniques of identification and enumeration / Análise comparativa da distribuição das famílias Salpidae e Doliolidae em relação ao zooplâncton total na plataforma continental sudeste do Brasil por meio de técnicas semi-automáticas de identificação e contagem
AUTOR(ES)
Lilian Prescinoti de Oliveira
DATA DE PUBLICAÇÃO
2009
RESUMO
The abundance of thaliaceans and its relation to other zooplankton groups, as well as salp grazing impact, were studied on the southeastern shelf of Brazil based on samples collected during summer 2002. Salps occurred at higher numbers on the inner shelf, while doliolids were more abundant on the outer shelf. Both taxa were found mainly in the upper layers of the water column. Highest biomass values were recorded in stations where gelatinous plankton were present, with maxima of 131 mg C m-² for salps and 636 mg C m-² for doliolids. Salp occurrence was positively corelated to higher chlorophyll concentrations and lower temperatures. Doliolids did not follow such pattern. Salps were associated to areas where Tropical Water and South Atlantic Central Water mixed, and doliolids dominated in Tropical Water. The abundance of other zooplankton taxa did not show significant decrease when salps and doliolids were abundant, as the correlation among salps, doliolids and other groups were usually positive. During upwelling events food is usually not limiting; thus the same planktonic taxa that will compete for food in other areas may coexist in such eutrophic to mesotrophic environments. The highest ingestion rates and feeding impact associated to salps were recorded on the inner shelf, where the highest salp abundance and chlorophyll-a concentration occurred.
ASSUNTO(S)
distribuição vertical doliolids dolíolos distribuição horizontal feeding impact salpa impacto alimentar ingestion rate ressurgência. abundância abundance taxa de ingestão horizontal distribution upwelling vertical distribution
