O GT3.0 (Variabilidade Climática, Ciclos Biogeoquímicos e Fluxo de CO2 no Oceano Atlântico Tropical) publicou em abril de 2021 um novo artigo na Frontiers in Marine Science (IF: 3.661) intitulado "Surface Circulation and Vertical Structure of Upper Ocean Variability Around Fernando de Noronha Archipelago and Rocas Atoll During Spring 2015 and Fall 2017" de autoria de Alex Costa da Silva, Alexis Chaigneau, Alina N. Dossa, Gerard Eldin, Moacyr Araujo e Arnaud Bertrand
ABSTRACT
Using current, hydrographic and satellite observations collected off Northeast Brazil around the Fernando de Noronha Archipelago and Rocas Atoll during two oceanographic cruises (spring 2015 and fall 2017), we investigated the general oceanic circulation and its modifications induced by the islands. In spring 2015, the area was characterized by lower SST (26.6◦C) and deep mixed-layer (∼90 m). At this depth, a strong current shear was observed between the central branch of the eastward flowing near-surface South Equatorial Current and the westward flowing South Equatorial Undercurrent. In contrast, in fall 2017, SST was higher (∼28.8◦C) and the mixed-layer shallower (∼50 m). The shear between the central South Equatorial Current and the South Equatorial Undercurrent was weaker during this period. Interestingly, no oxygen- rich water from the south (retroflection of the North Brazil undercurrent) was observed in the region in fall 2017. In contrast, we revealed the presence of an oxygen-rich water entrained by the South Equatorial Undercurrent reaching Rocas Atoll in spring 2015. Beside these global patterns, island wake effects were noted. The presence of islands, in particular Fernando de Noronha, strongly perturbs central South Equatorial Current and South Equatorial Undercurrent features, with an upstream core splitting and a reorganization of single current core structures downstream of the islands. Near islands, flow disturbances impact the thermohaline structure and biogeochemistry, with a negative anomaly in temperature (−1.3◦C) and salinity (−0.15) between 200 and 400 m depth in the southeast side of Fernando Noronha (station 5), where the fluorescence peak (>1.0 mg m−3) was shallower than at other stations located around Fernando de Noronha, reinforcing the influence of flow-topography. Satellite maps of sea- surface temperature and chlorophyll-a confirmed the presence of several submesoscale features in the study region. Altimetry data suggested the presence of a cyclonic
O artigo foi acessado no formato "Open Access"e pode ser acessado no seguinte "link": https://doi.org/10.3389/fmars.2021.598101
O GT2.2 (Variabilidade Espaço-Temporal da Diversidade e Estrutura Trófica do Ambiente Pelágico na Plataforma Continental) tem uma novo artigo publicado no Journal of the Marine Biological Association of the United Kingdom (FI: 1.181) intitulado "Factors affecting the seasonal variability of planktonic shrimps (Dendrobranchiata) along an estuary–ocean gradient on the Amazon continental shelf" de autoria de Leiliane Souza da Silva, Danielle Viveiros Cavalcante-Braga, Caio Brito Lourenço, Ralf Schwamborn e Jussara Moretto Martinelli-Lemos.
ABSTRACT
Dendrobranchiata shrimp taxonomic composition and spatial and temporal distribution on the Amazon continental shelf (ACS) were investigated along a transect between the sources of the Amazon and Pará Rivers, encompassing an extension of !250 km towards the contin- ental slope. Plankton was collected with oblique trawls (200 !m mesh size), and nine taxa were found; 59.4% were larvae (mysis or decapodid stages) and 40.6% were juveniles or adults. Acetes was negatively related to chlorophyll-a and temperature, and Luciferidae were posi- tively correlated with months. This study provides novel information on the density distribu- tion of dendrobranchiate shrimps, thus helping to pave the way to characterize a large-scale, hugely relevant area that is poorly studied. As in other tropical coastal areas, there is here an increase in number of taxa with increased distance from the coast. Luciferidae, Solenoceridae and Penaeidae were the most frequent families whereas Sicyoniidae and Sergestidae had the lowest frequency of occurrence nearer the slope. Despite the low larval density of penaeid shrimps, their presence in all months and at all sampling sites along the ACS proves the importance of this area for shrimps with socioeconomic relevance, as well as its importance as a nursery and growth habitat for dendrobranchiate shrimps.
O trabalho completo pode ser acessado em:
https://doi.org/10.1017/S0025315421.000308
ou solicitando diretamente a autora correspondente: Jussara Moretto Martinelli-Lemos, e-mail: jussara@ufpa.br
Atualizado: 27 de abr. de 2021
Saiu publicado no periódico Ocean and Costal Management (IF=2.482) um novo trabalho no âmbito do inctAmbTropic Fase II intitulado "Evaluation of decadal shoreline changes along the Parnaíba Delta (NE Brazil) using satellite images and statistical methods" de autoria de Thiago Augusto Bezerra Ferreira , André Giskard Aquino da Silva, Yoe Alain Reyes Perez, Karl Stattegger e Helenice Vital, que investiga o comportamento da linha de costa do delta do Parnaíba no período 1984-2017. O trabalho concluiu que a redução na descarga fluvial do rio Parnaíba entre 1995-1999 e 2009-2012 foi a causa principal do recuo erosivo experimentado pelo delta.
Comportamento da linha de costa do delta do Parnaíba entre 1984-2017. Vermelho: erosão. Verde: progradação.
ABSTRACT
This study investigated changes of the shoreline position in the Parnaíba River Delta (PRD), which is in an underdeveloped and sparsely populated area. The general behavior of the shoreline between 1984 and 2017 was analyzed using 12 Landsat satellite images and the Digital Shoreline Analysis System (DSAS) software. DSAS applied statistical methods, such as Weighted Linear Regression (WLR) and End Point Rate (EPR), to define whether the shoreline was retreating or accreting. Data analysis revealed that, on a decadal time scale (33 years), 52% of the PRD shoreline retreated under erosional conditions, while 48% accreted. Accretion mainly occurred at the vicinities of the river mouth, especially eastward where the highest progradation rate was observed (maximum of 29 m/year). Shoreline retreat, up to 9 m/year, occurred predominantly in the western part of the PRD and away from the river mouth. However, changes of the general behavior of the shoreline (retreat/accretion) were observed at an inter- decadal time scale, which were positively related to variations in river discharge. Variations of river discharge are directly dependent on the rainfall amount along the drainage basin that, in this region, is controlled by climatic conditions such as El Niño and La Niña. Therefore, the reduced river discharge observed between 1995- 1999 and 2009–2012 (El Niño periods), was the major cause the triggered the observed coastal retreat (>6 m/ year) on PRD shoreline during these periods. Consequently, the variability of natural factors, such as river discharge and rainfall, are the main drivers of shoreline changes on PRD, since anthropogenic impacts have hitherto only marginal effects on the delta region and on the drainage basin of the Parnaíba river.
O trabalho completo pode ser acessado em: https://doi.org/10.1016/j.ocecoaman.2020.105513