Dataset Information

Tropical South Atlantic influence on Northeastern Brazil precipitation and ITCZ displacement during the past 2300 years.

ABSTRACT: Recent paleoclimatic studies suggest that changes in the tropical rainbelt across the Atlantic Ocean during the past two millennia are linked to a latitudinal shift of the Intertropical Convergence Zone (ITCZ) driven by the Northern Hemisphere (NH) climate. However, little is known regarding other potential drivers that can affect tropical Atlantic rainfall, mainly due to the scarcity of adequate and high-resolution records. In this study, we fill this gap by reconstructing precipitation changes in Northeastern Brazil during the last 2,300 years from a high-resolution lake record of hydrogen isotope compositions of plant waxes. We find that regional precipitation along the coastal area of South America was not solely governed by north-south displacements of the ITCZ due to changes in NH climate, but also by the contraction and expansion of the tropical rainbelt due to variations in sea surface temperature and southeast trade winds in the tropical South Atlantic Basin.

SUBMITTER: Utida G

PROVIDER: S-EPMC6368536 | biostudies-other | 2019 Feb

REPOSITORIES: biostudies-other

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Tropical South Atlantic influence on Northeastern Brazil precipitation and ITCZ displacement during the past 2300 years.

Utida Giselle G Cruz Francisco W FW Etourneau Johan J Bouloubassi Ioanna I Schefuß Enno E Vuille Mathias M Novello Valdir F VF Prado Luciana F LF Sifeddine Abdelfettah A Klein Vincent V Zular André A Viana João C C JCC Turcq Bruno B

Scientific reports 20190208 1

Recent paleoclimatic studies suggest that changes in the tropical rainbelt across the Atlantic Ocean during the past two millennia are linked to a latitudinal shift of the Intertropical Convergence Zone (ITCZ) driven by the Northern Hemisphere (NH) climate. However, little is known regarding other potential drivers that can affect tropical Atlantic rainfall, mainly due to the scarcity of adequate and high-resolution records. In this study, we fill this gap by reconstructing precipitation changes ...[more]

PMID: 30737460

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Project description:The phylogeography of the holoplanktonic chaetognath Flaccisagitta enflata was investigated in the Tropical Western Atlantic (TWA). Considering the cosmopolitan range of this species and the fact that its entire life cycle is planktonic, the central hypothesis of this study is that F. enflata exhibits connectivity due to its high dispersal capacity, forming a panmictic population among the study sites. The evaluated areas included neritic (Port of Recife-PR, and Tamandaré - TA) and oceanic (Fernando de Noronha Archipelago-FN, Rocas Atoll-RA, Guará seamount-GS and Saint Peter and Saint Paul's Archipelago-SPSPA) locations of the Brazilian Blue Amazon. We used COI gene sequences as molecular marker. Partial sequences (425 bp) were obtained for 116 specimens and employed to reconstruct the phylogeny, build an haplotype network, evaluate gene flow through a migration model, and estimate diversity indices, population structuring and demographic history. High levels of haplotype diversity (mean: 0.98) and moderate to high levels of nucleotide diversity (mean: 0.023) were observed. The phylogeny and the haplotype network topologies showed some geographic clustering, indicating local structuring in GS and PR. This finding was supported by the AMOVA high global Φst (0.033, significant) and some pairwise Φst comparisons (7 out of 15 were significantly >0). Significant differences suggested lower levels of connectivity when GS population was compared to those of FN and SPSPA; as well as when TA was compared to FN. These results might be related to particularities of the oceanic dynamics which rules the TWA, sustaining such dissimilarities. Structuring was also observed between PR and all oceanic locations. We hypothesize that the topography of the port inlet, enclosured by a reef barrier, may constrain the water turnover ratio and thus migration rates of F. enflata in the TWA. Accordingly, Migrate-N yielded a four metapopulations model (PR ⇌ TA ⇌ SPSPA+FN ⇌ GS+RA) as the best (highest probability; ~0.90) to represent the structuring of F. enflata in the TWA. Therefore, the null hypothesis of one randomly mating population cannot be accepted. The demographic evaluation demonstrated that the neutral hypothesis of stable populations may not be rejected for most of the locations. This work is the start point to broaden the knowledge on the phylogeography and population genetic structure of a numerically dominant species in the Western Atlantic, with key role in the marine trophic web.

Dataset Information

Tropical South Atlantic influence on Northeastern Brazil precipitation and ITCZ displacement during the past 2300 years.

Publications

Tropical South Atlantic influence on Northeastern Brazil precipitation and ITCZ displacement during the past 2300 years.

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