Pedological Studies of Subaqueous Soils as a Contribution to the Protection of Seagrass Meadows in Brazil

Nóbrega, Gabriel Nuto; Romero, D.J.; Otero, Xosé Luís; Ferreira, Tiago Osório

doi:10.1590/18069657rbcs20170117

Cited by 10 publications

(16 citation statements)

References 44 publications

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“…The aboveground (AGB) and belowground (BGB) biomass and TECS in Brazilian mangroves (Figure 2B) may present heterogeneity based on geomorphic and sedimentary settings, soil depth, tidal height, salinity, climate, environmental protection measures, and forest structure (Kauffman et al, 2018a;Kauffman et al, 2018b;Nobrega et al, 2018;Rovai et al, 2018;Kauffmann et al, 2020;Hatje et al, 2020;Matos et al, 2020;Rovai et al, 2020;Rovai et al, 2022) (Table 2). The belowground portion (including soils and roots) represents approximately 70%-86% of the total carbon stocks in mangroves (Hamilton and Friess, 2018;Kauffman et al, 2018a;Kauffmann et al, 2020).…”

Section: Mangrove Forestsmentioning

confidence: 99%

Blue Carbon Ecosystems in Brazil: Overview and an Urgent Call for Conservation and Restoration

et al. 2022

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In this article, we discuss knowledge and gaps regarding blue carbon ecosystems (BCEs) in Brazil, considering the urgency to apply protection actions and policies to safeguard their biodiversity and associated ecosystem services. We also indicate areas of further research to improve carbon stocks and sequestration rate estimates. We call attention to the shortage of studies on Brazilian BCEs relative to the growing knowledge on the Blue Carbon Framework accumulated worldwide over the last decade. Considering the extensive Brazilian Economic Exclusive Zone (known as “Blue Amazon”), knowledge concerning blue carbon stocks is vital at regional and global scales for mitigating global increases in atmospheric carbon dioxide (CO2). The Blue Amazon has at least 1,100,000 ha of vegetated and non-vegetated coastal ecosystems (mangroves, salt marshes, seagrass meadows, and hypersaline tidal flats) that collectively contain vast amounts of stored carbon, making Brazil an ideal place to test mechanisms for evaluating, conserving, and restoring BCEs. Other poorly understood potential sinks and sources of carbon are macroalgal and rhodolith beds, mudflats, continental shelf sediments, and marine animal forests in shallow, mesophotic, and deep waters. The carbon fluxes between diverse environmental compartments, such as soil–air, soil–water, groundwater–water–surface water, air–water, and land–ocean, in BCEs across the Blue Amazon must be studied. We emphasize the importance of assessing the total carbon stock and the recent dismantling of environmental laws that pose great risks to these important BCEs. The conservation and recovery of these areas would enhance the carbon sequestration capacity of the entire country. Furthermore, we highlight priorities to improve knowledge concerning BCEs and their biogeochemical cycles in the Blue Amazon and to provide information to assist in the reduction of atmospheric levels of CO2 for the United Nations Decade of Ocean Science (2021–2030).

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Section: Mangrove Forestsmentioning

confidence: 99%

Blue Carbon Ecosystems in Brazil: Overview and an Urgent Call for Conservation and Restoration

et al. 2022

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“…For the present study, data corresponding to six representative profiles (two at each study site) are presented. Soil profiles were sampled using transparent polycarbonate tubes (1.5 m long, 90 mm diameter) attached to an auger for submerged soils (Supplementary File; Nóbrega et al 2018). After sampling, the soil cores were carefully removed from the tubes and the soil profiles were morphologically described (Fig.…”

Section: Soil and Water Samplingmentioning

confidence: 99%

Masked diversity and contrasting soil processes in tropical seagrass meadows: the control of environmental settings

Nóbrega

Otero

Romero³

et al. 2022

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Abstract. Seagrass meadows are among the most valuable ecosystems on Earth. However, in tropical countries, there is a substantial knowledge gap on “seagrass science”. To address this gap, seagrass soils from three Brazilian coastal regions were investigated (the NE, SE, and S coasts). Soil profiles from different geological and bioclimatic settings were sampled, described, and analyzed. Detailed macromorphological descriptions, soil classification, physicochemical analysis (soil particle size, soil pH, pHoxidation, Eh, total organic carbon; TOC), Fe partitioning, and X-ray diffractometry were performed. Water samples were analyzed for pH, salinity, and ion concentrations. Different environmental settings in the coastal compartments produced contrasting geochemical conditions, which caused different intensities of pedogenetic processes. On the NE coast, the denser plant coverage favored higher TOC contents (2.5±0.1 %) and an anaerobic environment (Eh = +134 ± 142 mV), prone to an intense sulfidization (i.e., pyritic Fe formation; Py-Fe). Py-Fe contents in NE soils were 6-fold and 2-fold higher than those in the SE and S coastal soils, respectively. Conversely, lower TOC contents (0.35 ± 0.15 %) and a suboxic environment (Eh +203 ± 55 mV) in the SE soils, along with the Fe-rich geological surroundings, decreased the intensity of gleization. The contrasting intensities in the soil processes, related to the (seemingly subtle) differences in the geochemistry of each environment, ultimately caused relevant pedodiversity among the studied sites. Our findings contribute to a better understanding of the general functioning of tropical seagrass meadows but also have important environmental implications for studies focused on carbon sequestration in these ecosystems.

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“…Until recently, the substrate below marine phanerogams has been studied as sediment by marine biologists and chemists. The recent interest from a soil science perspective has resulted in a few publications in which seagrass substrates are envisioned as soils [3][4][5][6], triggering discussion about their classification as sediment or soil [7]. Regardless of the terminology used, the plant/substrate interactions lead to physico-chemical changes that dramatically modify the texture [8,9] and composition [10][11][12][13], increase organic matter content (OM) [14], microbial populations and diversity [15][16][17][18], while changing redox potential [19].…”

Section: Introductionmentioning

confidence: 99%

Pedogenic Processes in a Posidonia oceanica Mat

et al. 2020

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Scientists studying seagrasses typically refer to their substratum as sediment, but recently researchers have begun to refer to it as a soil. However, the logistics of sampling underwater substrata and the fragility of these ecosystems challenge their study using pedological methods. Previous studies have reported geochemical processes within the rhizosphere that are compatible with pedogenesis. Seagrass substratum accumulated over the Recent Holocene and can reach several meters in thickness, but studies about deeper layers are scarce. This study is a first attempt to find sound evidence of vertical structuring in Posidonia oceanica deposits to serve as a basis for more detailed pedological studies. A principal component analysis on X-Ray Fluorescence-elemental composition, carbonate content and organic matter content data along a 475 cm core was able to identify four main physico-chemical signals: humification, accumulation of carbonates, texture and organic matter depletion. The results revealed a highly structured deposit undergoing pedogenetical processes characteristic of soils rather than a mere accumulation of sediments. Further research is required to properly describe the substratum underneath seagrass meadows, decide between the sediment or soil nature for seagrass substrata, and for the eventual inclusion of seagrass substrata in soil classifications and the mapping of seagrass soil resources.

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Pedological Studies of Subaqueous Soils as a Contribution to the Protection of Seagrass Meadows in Brazil

Cited by 10 publications

References 44 publications

Blue Carbon Ecosystems in Brazil: Overview and an Urgent Call for Conservation and Restoration

Blue Carbon Ecosystems in Brazil: Overview and an Urgent Call for Conservation and Restoration

Masked diversity and contrasting soil processes in tropical seagrass meadows: the control of environmental settings

Pedogenic Processes in a Posidonia oceanica Mat

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