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  • 1
    Electronic Resource
    Electronic Resource
    Particulate and dissolved phases as indicators of limnological and ecophysiological spatial variation in Cima Lake system, Brazil: a case study (1999)
    Springer
    Hydrobiologia 411 (1999), S. 89-101 
    Details
    ISSN: 1573-5117
    Keywords: ecophysiology ; organic matter ; phytoplankton ; freshwater lake ; nutrients ; spatial variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The spatial distribution and behavior of limnological variables were studied in a fluvial-lacustrine system, in northern Rio de Janeiro State, Brazil. Physical (e.g. temperature, transparency), physico-chemical (e.g. pH, conductivity), chemical (e.g. inorganic nutrients, dissolved oxygen, particulate and dissolved organic carbon), biochemical (water-soluble carbohydrates – SCHO, total proteins – TPROT, chlorophyll a – Chl a and carotenoids – CAR) and biological (phytoplankton taxa composition) variables were assessed in water-column. Results from dissolved and particulate phases varied considerably among sampling sites. The studied variables indicated some relationships, in limnetic zone, between inorganic compounds and organic products (biochemical). In comparison to lake and outflow (channel) waters, the main inflow (stream) body water was characterized by lower concentrations of particulate biochemical variables and higher concentrations of dissolved inorganic-N. Gross biochemical composition of POC and DOC indicated spatial variation in the fluvial-lacustrine system with the minor participation of TPROT-C (total protein carbon) and SCHO-C (water-soluble carbohydrate carbon) in the center of the lake. At the horizontal space of the lacustrine system, at the ends of the lake, it was also observed a shift between the relative participation of TPROT-C and SCHO-C in POC. Ecophysiological state and nature of particulate matter were also evaluated through photosynthetic pigment concentrations, light microscope analysis, (C:N)a, C:Chl a, SCHO:TPROT, TPROT:Chl a and SCHO:Chl a ratios. Spatial variations were recognized in the fluvial-lacustrine system and were linked to a variety of factors such as the nature (detrital vs. living plankton algae) and origin (allochthonous vs. autochthonous) of the suspended particulate matter, hydrological characteristic of the environments (lotic vs. lentic), phytoplankton metabolical responses induced by nitrogen deficiencies, and wind stress. Additionally, based on the present concentrations of Chl a and the high proportion of the cyanobacterium Cylindrospermopsis raciborskii (∼ 90%) in Cima Lake phytoplankton composition we point out that the lacustrine system has suffered profound limnological changes from the last 10 years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003881129950
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Carbon and alkalinity outwelling across the groundwater‐creek‐shelf continuum off Amazonian mangroves (2021)
    In:  EPIC3Limnology and Oceanography Letters, 6(6), pp. 369-378, ISSN: 2378-2242
    Details
    Publication Date: 2022-01-03
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 3
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    Carbon and alkalinity outwelling across the groundwater‐creek‐shelf continuum off Amazonian mangroves (2021)
    ASLO (Association for the Sciences of Limnology and Oceanography) | Wiley
    Details
    Publication Date: 2024-02-07
    Description: Lateral fluxes (i.e., outwelling) of dissolved organic (DOC) and inorganic (DIC) carbon and total alkalinity were estimated using radium isotopes at the groundwater, mangrove creek, and continental shelf scales in the Amazon region. Observations of salinity and radium isotopes in the creek indicated tidally driven groundwater exchange as the main source of carbon. Radium-derived transport rates indicate that mangrove carbon is exported out of the continental shelf on timescales of 22 ± 7 d. Bicarbonate was the main form (82% ± 11%) of total dissolved carbon in all samples, followed by DOC (13% ± 12%) and CO2 (5% ± 4%). DIC (18.7 ± 15.7 mmol m−2 d−1) exceeded DOC (3.0 ± 4.1 mmol m−2 d−1) outwelling at all spatial scales. The interpretation of outwelling across the mangrove-ocean continuum is related to the spatial and temporal scales investigated. At all scales, outwelling represented a major coastal carbon pathway driving bicarbonate storage in the ocean.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Historic variation of trace elements in pinnipeds with spatially segregated trophic habits reveals differences in exposure to pollution (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Marine mammals and the ecological functions they provide to coastal and pelagic ecosystems are increasingly threatened by the intensification of anthropogenic impacts. The Uruguayan coastline throughout the 20th century, like other coastal environments worldwide, has been the sink of a variety of trace metals derived from the rapid urbanization and industrialization of related land areas. This coastline is inhabited by two species of pinnipeds trophically and spatially segregated. Otaria byronia feeds in coastal environments while Arctocephalus australis preysmainly offshore. The present study aimed to analyze historic changes in concentrations of trace elements in teeth of both species from 1941 to the present day. We analyzed the dentin of 94 canine teeth using stable isotope analysis (delta C-13) and ICP-MS to determine their feeding areas and the concentration of 10 trace elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) respectively. The concentration of Cr was significantly higher during '70-'80s, in both species coinciding with tannery industry development. Both species of pinnipeds have been differentially exposed to trace elements depending on their feeding area. A pelagic diet, possibly based on squid, increased the concentration of Cd in A. australis, while O. byronia has been more exposed to anthropogenic Pb and Cu associated to a costal and more benthic diet. Our results highlight dentin as a reliable matrix for historic studies on the exposure to trace elements. In light of our results, the O. byronia's declining population could be the result of the synergistic effects of trace elements together with other ecological pressures faced in their environment.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Barium and its Importance as an Indicator of (Paleo)Productivity (2016)
    Academia Brasileira de Ciências
    Details
    Publication Date: 2023-06-29
    Description: Barium (Ba) is a trace element which occurs predominantly as barite mineral (BaSO4) in the marine environment. Previous work suggests that barite concentrations are related to the organic carbon flux and marine biological debris in the water column suggesting a direct or indirect involvement in the marine biological cycling. In addition, barite has a high preservation rate (~30%) in sediments and it is less affected by early diagenesis than other proxies for productivity such as carbonates (~10%) and organic carbon (~1%), for example. Therefore, Ba is considered an excellent proxy for ocean (paleo)productivity. However, correlating barite to productivity involves some caveats. Specifically, the post-depositional formation of barite in oxic sediments can lead to Ba release into porewaters under anoxic conditions, which can form barite again under oxic conditions. This diagenetic formation is not correlated to export production as the seawater authigenic barite formed with decaying organic matter in the water column. Therefore, the main goal of this work is to briefly review the marine Ba cycle and highlight its importance for (paleo)productivity research.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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