Vertical migration, nitrate uptake and denitrification: survival mechanisms of foraminifers (Globobulimina turgida) under low oxygen conditions

TitreVertical migration, nitrate uptake and denitrification: survival mechanisms of foraminifers (Globobulimina turgida) under low oxygen conditions
Type de publicationArticle de revue
AuteurKoho, Karoliina Annika, Piña-Ochoa, Elisa, Geslin, Emmanuelle , Risgaard-Petersen, Nils
EditeurWiley
TypeArticle scientifique dans une revue à comité de lecture
Année2011
LangueAnglais
Date2011/02/01
Numéro2
Pagination273 - 283
Volume75
Titre de la revueFEMS Microbiology Ecology
ISSN1574-6941
Mots-clésbenthic foraminifera, denitrification, migration, nitrate uptake, pseudopodia
Résumé en anglais

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.

URL de la noticehttp://okina.univ-angers.fr/publications/ua3859
DOI10.1111/j.1574-6941.2010.01010.x
Lien vers le document

http://dx.doi.org/10.1111/j.1574-6941.2010.01010.x