The influence of surface low-salinity waters and cold subsurface water masses on picoplankton and ultraplankton distribution in the continental shelf off Rio de Janeiro, SE Brazil

Moser, Gleyci Aparecida Oliveira; Castro, Nathália Oliveira de; Takanohashi, Robson Alves; Fernandes, Alexandre Macedo; Pollery, Ricardo; Tenenbaum, Denise Rivera; Guerra, Josefa Varela; Barrera-Alba, José Juan; Ciotti, Áurea Maria

doi:10.1016/j.csr.2016.02.017

Cited by 12 publications

(4 citation statements)

References 64 publications

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“…At the surface layer, the presence of a seasonal thermocline was prominent in all stations forming a shallow upper mixed layer in the innermost stations that was thicker in the offshore stations, most likely due to deeper solar light penetration. Such a strong stratification led to the establishment of a nutricline, thus influencing nutrient supply from underneath layers and limiting the development of autotrophic communities in the surface euphotic layer (Brandini, 1990;Brandini et al, 2014;Moser et al, 2016;Bergo et al, 2017). Due to the predominance of northeasterly winds and the influence of Ekman transport during spring and summer, CW is displaced offshore allowing for the intrusion of SACW through the SBB (Castro, 2014).…”

Section: Discussionmentioning

confidence: 99%

Hydrography-Driven Variability of Optically Active Constituents of Water in the South Brazilian Bight: Biogeochemical Implications

et al. 2019

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The South Brazilian Bight (SBB) is a hydrographically dynamic environment with strong seasonality that sustains a diverse planktonic community involved in diverse biogeochemical processes. The inherent optical properties (IOPs; e.g., absorption and scattering coefficients) of optically actives constituents of water (OACs; phytoplankton, non-algal particles-NAP, and colored dissolved organic matter-CDOM) have been widely employed to retrieve information on biogeochemical parameters in the water. In this study conducted in the SBB, a cross-shelf transect was performed for biogeochemistry and hydrographic sampling during a summer expedition. Our research aimed to determine the distribution and amount of the OACs based on their spectral signature, in relation to the distribution of water masses in the region. That allows us to get insights into the biogeochemical processes within each water mass and in the boundaries between them. We observed a strong intrusion of South Atlantic Central Water (SACW) over the shelf, mainly driven by the wind action. With that, phytoplankton development was fueled by the input of nutrients, and increased chlorophyll-a (Chl-a) concentrations were observed within the shallowest stations. Colored dissolved organic matter did not follow the distribution of dissolved organic carbon (DOC). Both CDOM and DOC presented high values at the low salinity Coastal Water (CW), as an indication of the continental influence over the shelf. However, CDOM was inversely correlated with salinity and lowest values were observed within Tropical Water (TW), whereas DOC values within TW were as high as within CW, indicating an autochthonous DOM source. Additionally, a deep Chl-a maximum (DCM) was noticed in the boundary between the TW and SACW. Along with the DCM, we observed the production of fresh, non-colored DOM attributed to the microbial community. Finally, our results suggest that CDOM is photodegraded at the surface of CW. This is mainly due to the Ekman transport effect over the region that traps CW at the surface, making it longer exposed to solar radiation.

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Section: Discussionmentioning

confidence: 99%

Hydrography-Driven Variability of Optically Active Constituents of Water in the South Brazilian Bight: Biogeochemical Implications

et al. 2019

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“…The autotrophic plankton assemblage is dominated mostly by picoplankton cells, represented mostly by the cyanobacterium Synechococcus (prokaryote) and, to a lesser extent, by picoeukaryotes (Gérikas Ribeiro et al, 2016;Moser et al, 2016;Bergo et al, 2017). This study assessed planktonic carbon metabolism in the Saco do Mamanguá Ría (Figure 1A), an inlet subsystem of the Bay of Ilha Grande (hereafter BIG, Lat 23 -23.5 • S; Long 43.5 -44.5 • W) that is representative of most of the alongshore Brazilian cyanobacteria-dominated oligotrophic coastal ecosystem.…”

Section: Introductionmentioning

confidence: 99%

Carbon Flow for Plankton Metabolism of Saco do Mamanguá Ría, Bay of Ilha Grande, a Subtropical Coastal Environment in the South Brazil Bight

et al. 2019

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The autotrophic plankton assemblage along the subtropical coastal embayments of the South Brazil Bight is dominated by the cyanobacterium Synechococcus. This investigation aims to assess its contribution to the total carbon metabolism within the planktonic system of Mamanguá Ría, a subsystem of the Bay of Ilha Grande, southeast Brazilian coast. We hypothesized that photosynthetic carbon fixation by cyanobacteria does not support the plankton metabolism inside the Ría. Net community production (NCP) was calculated from differences between gross community production (GCP) and dark community respiration rates measured by in situ incubations using the oxygen light-and-dark technique. Our results reveal the carbon budget inside the Ría is not balanced by autotrophic production. The deficit of net ecosystem production throughout the year ranged from 0.5 to 1.5 mg m −2 d −1 below what is necessary to sustain local plankton metabolism. We argue that the offset between daily GCP and total community respiration may be balanced by grazing of nano-heterotrophs on heterotrophic bacteria. Our conclusions apply to the majority of the meso-oligotrophic Brazilian inner shelf waters away from estuarine plumes and upwelling systems.

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“…They can also use organic compounds, such as urea and cyanate, as energy and nitrogen sources (Kitzinger et al, 2019). These abilities allowed the Thaumarchaeota to thrive in the Holocene, becoming an important link in the microbial loop and trophic web of the present BC in the SBB (Moser et al, 2016). In a future warmer scenario, studies using climate and niche models indicate an expansion of oligotrophic regions and replacing larger phytoplankton with smaller organisms (Cabre ́et al, 2015;S ̌olic ́et al, 2018).…”

Section: Composition Of the Marine Primary Producer Communitymentioning

confidence: 99%

Late Pleistocene to Holocene variations in marine productivity and terrestrial material delivery to the western South Atlantic

et al. 2022

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Despite the increased number of paleoceanographic studies in the SW Atlantic in recent years, the mechanisms controlling marine productivity and terrestrial material delivery to the South Brazil Bight remain unresolved. Because of its wide continental shelf and abrupt change in coastline orientation, this region is under the influence of several environmental forcings, causing the region to have large variability in primary production. This study investigated terrestrial organic matter (OM) sources and marine OM sources in the South Brazil Bight, as well as the main controls on marine productivity and terrestrial OM export. We analyzed OM geochemical (bulk and molecular) proxies in sediment samples from a core (NAP 63-1) retrieved from the SW Atlantic slope (24.8°S, 44.3°W, 840-m water depth). The organic proxies were classified into “terrestrial-source” and “marine-source” groups based on a cluster analysis. The two sources presented different stratigraphical profiles, indicating distinct mechanisms governing their delivery. Bulk proxies indicate the predominance of marine OM, although terrestrial input also affected the total OM deposition. The highest marine productivity, observed between 50 and 39 ka BP, was driven by the combined effects of the South Atlantic Central Water upwelling promoted by Brazil Current eddies and fluvial nutrient inputs from the adjacent coast. After the last deglaciation, decreased phytoplankton productivity and increased archaeal productivity suggest a stronger oligotrophic tropical water presence. The highest terrestrial OM accumulation occurred between 30 and 20 ka BP, with its temporal evolution controlled mainly by continental moisture evolution. Sea level fluctuations affected the distance between the coastline and the sampling site. In contrast, continental moisture affected the phytogeography, changing from lowlands covered by grasses and saltmarshes to a landscape dominated by mangroves and the Atlantic Forest. Our results suggest how the OM cycle in the South Brazil Bight may respond to warmer and dryer climate conditions.

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The influence of surface low-salinity waters and cold subsurface water masses on picoplankton and ultraplankton distribution in the continental shelf off Rio de Janeiro, SE Brazil

Cited by 12 publications

References 64 publications

Hydrography-Driven Variability of Optically Active Constituents of Water in the South Brazilian Bight: Biogeochemical Implications

Hydrography-Driven Variability of Optically Active Constituents of Water in the South Brazilian Bight: Biogeochemical Implications

Carbon Flow for Plankton Metabolism of Saco do Mamanguá Ría, Bay of Ilha Grande, a Subtropical Coastal Environment in the South Brazil Bight

Late Pleistocene to Holocene variations in marine productivity and terrestrial material delivery to the western South Atlantic

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