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Cânions Submarinos desempenham um importante papel nos ecossistemas marinhos ao provocar alterações locais na temperatura, salinidade, nutrientes, transporte de sedimentos e até mesmo poluentes no ambiente marinho. Marcos V. B. Silva e Tereza C. M. Araújo integrantes do inct AmbTropic II (GT2.1 - (Geodiversidade, Biodiversidade e Recursos Vivos da Plataforma Continental) publicaram nesta semana no periódico Frontiers in Marine Sciences (IF: 4.912) uma revisão sistemática sobre os cânions da América do Sul intitulado "The South American Advances in Submarine Canyons Studies and Their Link to the Ocean Decade"


Distribuição dos principais de cânions submarinos na América do Sul


ABSTRACT

Submarine canyons have a relevant role in marine ecosystems. They are responsible for oceanographic conditions such as variability of temperature and salinity, sediment transport, nutrients, and even pollutants amongst marine areas. Submarine canyon studies have been growing and reaching prominence due to their importance in the Blue Economy. Initiatives to promote sustainable development for the ocean have been discussed in the Ocean Decade. Although canyons studies are increasing, how can we integrate these with the Ocean Decade outcomes? Thus, we aim to demonstrate an overview of the advances of submarine canyons studies and their link to the Ocean Decade for South America. We analyzed 160 studies divided into spatiotemporal analysis and study approaches according to the Ocean Decade outcomes. We discuss these articles, building a timeline and argumentative topics considering the advances, and discuss gaps to predict the future of submarine canyons studies in the Ocean Decade and Blue Economy context.


O trabalho pode ser livremente acessado em: https://doi.org/10.3389/fmars.2021.764029

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Pesquisadores dos GTs 2.1 (Geodiversidade, Biodiversidade e Recursos Vivos da Plataforma Continental) e 3.0 (Variabilidade climática, ciclos biogeoquímicos e fluxo de CO2 no oceano Atlântico tropical) do inct AmbTropic II publicaram no Journal of Marine Sciences (IF: 2.542) um interessante trabalho que investiga as interações entre a topografia submarina e a circulação na região nordeste do Brasil. Esta interação pode ser considerada como um conjunto de processos que resultam da interação entre as correntes e gradientes topográficos especialmente aqueles associados com canyons submarinos, que apresentam um potencial para produzir ressurgência e transporte "cross-isobath" em margens continentais. O trabalho intitulado "Flow-topography interactions in the western tropical Atlantic boundary off Northeast Brazil" tem como autores Marcos V.B. Silva, Beatrice Ferreira, Mauro Maida, Syumara Queiroz, Marcus Silva, Humberto L. Varona, Tereza C.M. Araújo e Moacyr Araújo.



Resumo Gráfico


ABSTRACT

Flow-Topography Interaction can be considered as a particular set of processes resulting of the currents inter- action with a topographic gradient, specially associated with submarine canyon areas, which are important morphological features with potential to upwelling and cross-isobath transport on the continental margins. The South Pernambuco Continental Shelf (SPCS) and Pernambuco Plateau located on the Southwestern Tropical Atlantic (SWTA), present incised morphological features, highlighting the shelf valleys and blind canyons, which do not have a connection to the shelf or an onshore river system. They are likely features for interactions between the dominant along-shelf flow represented by the strong western boundary North Brazil Undercurrent. We investigated potential canyon induced upwelling and the respective mechanisms at the late spring/early fall context. CTD and reanalysis data from GLORYS12V1, and in situ bathymetric measurements were used to characterise the hydrodynamics and canyon morphology, respectively. Then, we combined both to obtain dimensionless numbers from dynamical scale analysis to infer possible imbalances of the acting forces. Rean- alysis data evidenced uplift at the slope not related to the blind canyons. CTD data indicated a seasonal variation of the intrusion of water masses, especially at the shelf-break for the Middle shelf valley and Campas shelf valley. A temperature difference of 2.5 ◦ C (2.0 ◦ C) between surface and deep waters was observed during the late spring. A stepwise temperature structure was present in both seasons, indicating instability below the mixed layer depth, the uplifting of isotherms, and the corrosion of the lower portion of the surface mixed layer. The dimensionless parameters analysis reveals highest Rossby values during the fall, mainly in Zieta shelf valley (R0=130.87) and Csv (R0=111.71), and lower values for the canyons of the Pernambuco Plateau. Our hypothesis is that the shelf valleys might play a role in conducting the uplifted slope water coast-ward. For the blind canyons, although no related upwelling was observed, reanalysis revealed the presence of a deep anti-cyclonic eddy at one of the blind canyon’s mouth. Rossby and Burger numbers indicate a weak geostrophic balance at the canyon rim, and instability of the horizontal length scale of the pressure gradient force, with tendency to vorticity control. While the paradigm that shelf and coastal waters off north-eastern Brazil are mostly oligotrophic in the surface is true, our observation of shallow (<60 m) subsurface uplift should be considered in future works in the SWTA.


O trabalho completo pode ser acessado em: https://doi.org/10.1016/j.jmarsys.2021.103690

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Nesta quinta-feira, 16 de dezembro, às 17h, a Virada Sustentável realizará uma mesa em parceria com o Fórum Clima Salvador, coletivo de mais de 25 entidades soteropolitanas ligadas à temática ambiental, para discutir como cidades litorâneas, a exemplo de Salvador, podem ser impactadas pela elevação do nível dos oceanos.


O debate terá a participação dos coordenadores do Fórum Clima Salvador e do Instituto Taoca, Virgílio Machado e Letícia Moura e do geólogo da Universidade Federal da Bahia (Ufba), Professor José Landim, convidado pelo grupo.


A mesa será mediada pela jornalista Luana Assiz e realizada na Sala do Coro do Teatro Castro Alves (TCA).


O evento será aberto ao público, mas com número reduzido de ingressos, que estarão disponíveis gratuitamente por meio da plataforma Sympla.


Os debates também serão transmitidos ao vivo no canal da Virada no YouTube (www.youtube.com/viradasustentavel).


As mesas serão seguidas de apresentações musicais.


Não perca!








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