Heterotrophic nitrogen fixation (acetylene reduction) during leaf-litter decomposition of two mangrove species from South Florida, USA

Type : ACL
Nature : Production scientifique
Au bénéfice du Laboratoire : Oui
Statut de publication : Publié
Année de publication : 1998
Auteurs (2) : PELEGRI S TWILLEY R,r
Revue scientifique : Marine Biology
Volume : 131
Fascicule : 1
Pages : 53-61
DOI : 10.1007/s002270050296
URL : -
Abstract : Heterotrophic nitrogen-fixation (acetylene reduction) was measured during decomposition (under dark conditions) of Rhizophora mangle L. and Avicennia germinans (L.) Stearn leaf litter. Nitrogen-fixation rates in leaf litter increased following 24 d incubation, then decreased after similar or equal to 44 d for both species. Maximum rates of 66.2 and 64.6 nmol C2H4 g(-1) dry wt h(-1) were reached by R. mangle and A. germinans leaf litter, respectively. Higher fixation rates of leaf litter were associated with an increase in water content and sediment particles on leaf surfaces of both species. Rates of nitrogen fixation by diazotrophs attached to sediment particles were not significantly different from zero. With additions of D-glucose, ethylene production rates increased by factors of 625-, 34- and 7-fold for sediment, R. mangle and A. germinans leaf litter, respectively, compared to rates prior to enrichment. These organically enhanced rates of nitrogen fixation on leaves could be accounted for by increased activity associated with attached sediment particles and not the leaf material. Total phenolics [reported as tannic acid equivalent (TAE) units] decreased nitrogen-fixation rates when added to D-glucose-enriched sediment at >20 mg TAE l(-1). Phenolic compounds could explain the initial lag in rates of nitrogen fixation during leaf-litter decomposition of R. mangle (initial content of 110.8 mg TAE g(-1) dry wt), but not of A. germinans (initial content of 23.4 mg TAE g(-1) dry wt). The higher phenolic content and reportedly lower carbon substrate of R. mangle did not result in species-specific differences in either the magnitude or temporal pattern of nitrogen fixation compared to A. germinans leaf litter. We conclude that the availability of organic substrates leached from the leaf litter along with colonization by the heterotrophic diazotrophs las indicated by sediment accumulation) controls nitrogen-fixation rates in a similar manner in the leaf litter of both species.
Mots-clés : CARBON; DETRITUS; DYNAMICS; ESTUARY; FORESTS; N-2 FIXATION; ORGANIC-MATTER; RED MANGROVE; RHIZOPHORA-MANGLE LEAVES; TERMINOS
Commentaire : Times Cited in Web of Science Core Collection: 31
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Citation :
Pelegri S, Twilley RR (1998) Heterotrophic nitrogen fixation (acetylene reduction) during leaf-litter decomposition of two mangrove species from South Florida, USA. Mar Biol 131: 53-61 | doi: 10.1007/s002270050296