Benthic foraminiferal distribution on the southeastern Brazilian shelf and upper slope

Autor(es)

Burone, Leticia ^{[1, 2]} ; de Mello e Sousa, Silvia Helena ^[1] ; de Mahiques, Michel Michaelovitch ^[1] ; Valente, Paulo ^[3] ; Ciotti, Aurea ^[4] ; Yamashita, Cintia ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Oceanog, BR-05508900 Sao Paulo - Brazil

^[2] Secc Oceanol, Fac Ciencias, Montevideo 11400 - Uruguay

^[3] Fac Ingn, Inst Fis, Montevideo 11000 - Uruguay

^[4] UNESP Campus Litoral Paulista, BR-11330900 Sao Vicente, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Marine Biology; v. 158, n. 1, p. 159-179, JAN 2011.
• Citações Web of Science: 19

Resumo

Foraminiferal data were obtained from 66 samples of box cores on the southeastern Brazilian upper margin (between 23.8A degrees-25.9A degrees S and 42.8A degrees-46.13A degrees W) to evaluate the benthic foraminiferal fauna distribution and its relation to some selected abiotic parameters. We focused on areas with different primary production regimes on the southern Brazilian margin, which is generally considered as an oligotrophic region. The total density (D), richness (R), mean diversity (H) over bar', average living depth (ALD(X) ) and percentages of specimens of different microhabitats (epifauna, shallow infauna, intermediate infauna and deep infauna) were analyzed. The dominant species identified were Uvigerina spp., Globocassidulina subglobosa, Bulimina marginata, Adercotryma wrighti, Islandiella norcrossi, Rhizammina spp. and Brizalina sp.. We also established a set of mathematical functions for analyzing the vertical foraminiferal distribution patterns, providing a quantitative tool that allows correlating the microfaunal density distributions with abiotic factors. In general, the cores that fit with pure exponential decaying functions were related to the oligotrophic conditions prevalent on the Brazilian margin and to the flow of the Brazilian Current (BC). Different foraminiferal responses were identified in cores located in higher productivity zones, such as the northern and the southern region of the study area, where high percentages of infauna were encountered in these cores, and the functions used to fit these profiles differ appreciably from a pure exponential function, as a response of the significant living fauna in deeper layers of the sediment. One of the main factors supporting the different foraminiferal assemblage responses may be related to the differences in primary productivity of the water column and, consequently, in the estimated carbon flux to the sea floor. Nevertheless, also bottom water velocities, substrate type and water depth need to be considered. (AU)

• Processo FAPESP: 03/10740-0 - Variações holocênicas na paleoprodutividade da Plataforma Continental Sudeste do Brasil
• Beneficiário: Michel Michaelovitch de Mahiques
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 06/59947-3 - Modelos troficos com base em foraminiferos bentonicos e sua utilizacao como proxies de produtividade na plataforma do atlantico sul.
• Beneficiário: Leticia Burone
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado