Preprints
https://doi.org/10.5194/egusphere-2022-466
https://doi.org/10.5194/egusphere-2022-466
 
27 Jul 2022
27 Jul 2022

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

Gabriel Nuto Nóbrega1, Xosé L. Otero2, Danilo Jefferson Romero3, Hermano Melo Queiroz3, Daniel Gorman4, Margareth da Silva Copertino5, Marisa de Cássia Piccolo6, and Tiago Osório Ferreira3 Gabriel Nuto Nóbrega et al.
  • 1Graduate Program in Geoscience (Geochemistry), Department of Geochemistry, Federal Fluminense University, Outeiro São João Batista, s/n, Niterói, RJ, Brazil. 24.020-141
  • 2CRETUS Institute, Departamento Edafoloxía e Química Agrícola, Facultade de Bioloxía, Universidade de Santiago de Compostela, Rúa Lope G Marzoa, s/n. Campus sur. 15782 Santiago de Compostela, Spain
  • 3Department of Soil Science, College of Agriculture Luiz de Queiroz, University of São Paulo, ESALQ/USP, Av. Pádua Dias 11, 13.418-260, Piracicaba, SP, Brazil
  • 4Commonwealth Scientific and Industrial Research Organization (CSIRO), Oceans and Atmosphere, Crawley, WA, Australia
  • 5Institute of Oceanography, Federal University of Rio Grande (FURG), Av. Itália Km 08, Carreiros, Rio Grande – RS, CEP: 96.201-900, Brazil
  • 6Laboratory of Nutrient Cycling, Center of Nuclear Energy in Agriculture, University of São Paulo, Av. Centenário 303, 13.400.970, Piracicaba, São Paulo, Brazil

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.

Gabriel Nuto Nóbrega et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-466', Livia Vittori Antisari, 31 Aug 2022
    • AC1: 'Reply on RC1', Tiago Osório Ferreira, 18 Oct 2022
  • RC2: 'Comment on egusphere-2022-466', Vanessa Wong, 22 Sep 2022
    • AC2: 'Reply on RC2', Tiago Osório Ferreira, 18 Oct 2022

Gabriel Nuto Nóbrega et al.

Gabriel Nuto Nóbrega et al.

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Short summary
The present study addresses the soil information gap in tropical seagrass meadows. The different geological and bioclimatic settings caused a relevant soil diversity. Contrasting geochemical conditions promote different intensities of soil processes. Seagrass soils from the NE semiarid coast are marked by a more intense sulfidization. Understanding soil processes may help in the sustainable management of seagrasses.