Vertical migration, nitrate uptake and denitrification: survival mechanisms of foraminifers (Globobulimina turgida) under low oxygen conditions
Autor: | Nils Risgaard-Petersen, K.A. Koho, Emmanuelle Geslin, Elisa Piña-Ochoa |
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Rok vydání: | 2010 |
Předmět: |
0106 biological sciences
Denitrification 010504 meteorology & atmospheric sciences Ecology biology 010604 marine biology & hydrobiology Rhizaria chemistry.chemical_element Sediment Artificial seawater biology.organism_classification 01 natural sciences Applied Microbiology and Biotechnology Microbiology Oxygen Foraminifera chemistry.chemical_compound chemistry Nitrate Environmental chemistry Botany Diel vertical migration 0105 earth and related environmental sciences |
Zdroj: | FEMS Microbiology Ecology. 75:273-283 |
ISSN: | 0168-6496 |
DOI: | 10.1111/j.1574-6941.2010.01010.x |
Popis: | 15NO3− isotope labelling experiments were performed to investigate foraminiferal nitrate uptake strategies and the role of pseudopodial networks in nitrate uptake. Globobulimina turgida were placed below the nitrate penetration depth in homogenized sediment cores incubated in artificial seawater containing 15NO3−. A nylon net prevented the vertical migration of foraminifera to strata containing nitrate and oxygen, but allowed potential access to such strata by extension of pseudopods. No 15NO3− was found in G. turgida in these cores, suggesting that foraminifera cannot extend their pseudopods for nitrate uptake through several millimetres of sediment, but must physically migrate upwards closer to nitrate-containing strata. However, foraminiferal migration patterns in control cores with no nylon net were erratic, suggesting that individuals move in random orientations until they find favourable conditions (i.e. free nitrate or oxygen). A second experiment showed that foraminifera actively collect nitrate both in the presence and in the absence of oxygen, although uptake was initiated faster if oxygen was absent from the environment. However, no systematic influence of the size of the intracellular nitrate pool on nitrate uptake was observed, as specimens containing a large range of intracellular nitrate (636–19 992 pmol per cell) were measured to take up 15NO3− at comparable rates. |
Databáze: | OpenAIRE |
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