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Shifts of the Brazil-Falklands/Malvinas Confluence in the western South Atlantic during the latest Pleistocene-Holocene inferred from dinoflagellate cysts

Texto completo
Autor(es):
Gu, Fang [1] ; Chiessi, Cristiano M. [2] ; Zonneveld, Karin A. F. [3] ; Behling, Hermann [1]
Número total de Autores: 4
Afiliação do(s) autor(es):
[1] Univ Goettingen, Dept Palynol & Climate Dynam, Untere Karspule 2, D-37073 Gottingen - Germany
[2] Univ Sao Paulo, Sch Arts Sci & Humanities, Rua Arlindo Bettio 1000, BR-03828000 Sao Paulo, SP - Brazil
[3] Univ Bremen, MARUM Ctr Marine Environm Sci, Leobener Str 8, D-28359 Bremen - Germany
Número total de Afiliações: 3
Tipo de documento: Artigo Científico
Fonte: PALYNOLOGY; v. 43, n. 3, p. 483-493, JUL 3 2019.
Citações Web of Science: 2
Resumo

The Brazil-Falklands/Malvinas Confluence (BFMC), a highly energetic convergence of surface currents in the western South Atlantic, has shifted southward in recent years and this shift is projected to progress in the future. Palaeoecological insights documenting past changes of these currents may help in anticipating future impacts on the environment. We used dinoflagellate cyst analyses from a marine sediment core to reconstruct environmental changes in the Argentine continental margin, western South Atlantic, during the last ca. 12,600 years. The dynamics of the BFMC were reconstructed using the relative frequency of warm-water indicators for the Brazil Current (BC) versus cold-water taxa thriving in the Falklands/Malvinas Current (FMC). We found that the latitudinal position of the BFMC was relatively stable with only minor amplitude migrations between 12.6 and 8.7 cal kyr BP, followed by periods with stronger shifts to the south and the north until 0.66 cal kyr BP. After that, the BFMC shifted continuously to the south. The increase in freshwater algae abundance after ca. 5.7 cal kyr BP suggests an increase in precipitation over the adjacent Rio de la Plata drainage basin in south-eastern South America. As previously documented, such an increase in precipitation was probably related to a higher El Nino-Southern Oscillation frequency and longer, stronger El Nino events since the mid-Holocene. The dinoflagellate cyst record indicates a phase of the enhanced presence of nutrient-rich waters over the core site between ca. 6.3 and 5.7 cal kyr BP, as well as from 0.66 cal kyr BP to the recent. The highest eutrophication in the ocean surface occurred during the last ca. 100 years, most probably due to stronger human impact in the area of the Rio de la Plata drainage basin. (AU)

Processo FAPESP: 13/50297-0 - Dimensions US-BIOTA São Paulo: integrando disciplinas para a predição da biodiversidade da Floresta Atlântica no Brasil
Beneficiário:Cristina Yumi Miyaki
Linha de fomento: Auxílio à Pesquisa - Programa BIOTA - Temático
Processo FAPESP: 12/17517-3 - Resposta da porção oeste do Oceano Atlântico às mudanças na circulação meridional do Atlântico: variabilidade milenar a sazonal
Beneficiário:Cristiano Mazur Chiessi
Linha de fomento: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Jovens Pesquisadores