title: Carbon mineralization pathways and bioturbation in coastal Brazilian sediments.
abstract: Carbon mineralization processes and their dependence on environmental conditions (e.g. through macrobenthic bioturbation) have been widely studied in temperate coastal sediments, but almost nothing is known about these processes in subtropical coastal sediments. This study investigated pathways of organic carbon mineralization and associated effects of macrobenthic bioturbation in winter and summer (September 2012 and February 2014) at the SE Brazilian coast. Iron reduction (FeR) was responsible for 73-81% of total microbial carbon mineralization in September 2012 and 32-61% in February 2014. Similar high rates of FeR have only been documented a few times in coastal sediments and can be sustained by the presence of large bioturbators. Denitrification accounted for 5-27% of total microbial carbon mineralization while no SO4(2-) reduction was detected in any season. Redox profiles suggested that conditions were less reduced in February 2014 than in September 2012, probably associated with low reactivity of the organic matter, higher rates of aerobic respiration and bioirrigation by the higher density of small-macrofauna. Bioturbation by small macrofauna may maintain the sediment oxidized in summer, while large-sized species stimulate the reoxidation of reduced compounds throughout the year. Therefore, bioturbation seems to have an important role modulating the pathways of carbon mineralization in the area.
authors.affiliation: Instituto Oceanográfico da Universidade de São Paulo, Praça do Oceanográfico, 191, Cidade Universitária, 05508-120, São Paulo, Brazil.|Department of Biology, University of Southern Denmark, Campusvej 55, Odense M, 5230, Denmark.
authors.forename: Cintia O
authors.initials: CO
authors.lastname: Quintana
authors.affiliation: Instituto Oceanográfico da Universidade de São Paulo, Praça do Oceanográfico, 191, Cidade Universitária, 05508-120, São Paulo, Brazil.
authors.forename: Maurício
authors.initials: M
authors.lastname: Shimabukuro
authors.affiliation: Instituto Oceanográfico da Universidade de São Paulo, Praça do Oceanográfico, 191, Cidade Universitária, 05508-120, São Paulo, Brazil.
authors.forename: Camila O
authors.initials: CO
authors.lastname: Pereira
authors.affiliation: Instituto Oceanográfico da Universidade de São Paulo, Praça do Oceanográfico, 191, Cidade Universitária, 05508-120, São Paulo, Brazil.
authors.forename: Betina G R
authors.initials: BG
authors.lastname: Alves
authors.affiliation: Instituto Oceanográfico da Universidade de São Paulo, Praça do Oceanográfico, 191, Cidade Universitária, 05508-120, São Paulo, Brazil.
authors.forename: Paula C
authors.initials: PC
authors.lastname: Moraes
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, Odense M, 5230, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Valdemarsen
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, Odense M, 5230, Denmark.
authors.forename: Erik
authors.initials: E
authors.lastname: Kristensen
authors.affiliation: Instituto Oceanográfico da Universidade de São Paulo, Praça do Oceanográfico, 191, Cidade Universitária, 05508-120, São Paulo, Brazil.
authors.forename: Paulo Y G
authors.initials: PY
authors.lastname: Sumida
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry / Q000378:metabolism; D001938:Brazil; D001965:Bromides / Q000737:chemistry / Q000378:metabolism; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry / Q000378:metabolism; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D012621:Seasons; D012623:Seawater / Q000737:chemistry / Q000382:microbiology
chemical_list: D064751:Ammonium Compounds; D001965:Bromides; D009566:Nitrates; D002245:Carbon Dioxide; D002244:Carbon; D007501:Iron; D010100:Oxygen