title: Dinitrogen-fixing cyanobacteria in microbial mats of two shallow coral reef ecosystems.
abstract: Dinitrogen-fixing organisms in cyanobacterial mats were studied in two shallow coral reef ecosystems: La Reunion Island, southwestern Indian Ocean, Sesoko (Okinawa) Island, and northwestern Pacific Ocean. Rapidly expanding benthic miniblooms, frequently dominated by a single cyanobacterial taxon, were identified by microscopy and molecular tools. In addition, nitrogenase activity by these blooms was measured in situ. Dinitrogen fixation and its contribution to mat primary production were calculated using (15)N(2) and (13)C methods. Dinitrogen-fixing cyanobacteria from mats in La Reunion and Sesoko showed few differences in taxonomic composition. Anabaena sp. among heterocystous and Hydrocoleum majus and Symploca hydnoides among nonheterocystous cyanobacteria occurred in microbial mats of both sites. Oscillatoria bonnemaisonii and Leptolyngbya spp. occurred only in La Reunion, whereas Hydrocoleum coccineum dominated in Sesoko. Other mats dominated by Hydrocoleum lyngbyaceum, Phormidium laysanense, and Trichocoleus tenerrimus occurred at lower frequencies. The 24-h nitrogenase activity, as measured by acetylene reduction, varied between 11 and 324 nmoles C(2)H(2) reduced microg(-1) Chl a. The highest values were achieved by heterocystous Anabaena sp. performed mostly during the day. Highest values for nonheterocystous cyanobacteria were achieved by H. coccineum mostly during the night. Daily nitrogen fixation varied from nine (Leptolyngbya) to 238 nmoles N(2) microg(-1) Chl day(-1) (H. coccineum). Primary production rates ranged from 1,321 (S. hydnoides) to 9,933 nmoles C microg(-1) Chl day(-1) (H. coccineum). Dinitrogen fixation satisfied between 5% and 21% of the nitrogen required for primary production.
authors.affiliation: IRD, COM, Rue de la Batterie des Lions, 13007, Marseille, France. loic.charpy@univmed.fr
authors.forename: Loic
authors.initials: L
authors.lastname: Charpy
authors.forename: Katarzyna A
authors.initials: KA
authors.lastname: Palinska
authors.forename: Beatriz
authors.initials: B
authors.lastname: Casareto
authors.forename: Marie José
authors.initials: MJ
authors.lastname: Langlade
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Raeid M M
authors.initials: RM
authors.lastname: Abed
authors.forename: Stjepko
authors.initials: S
authors.lastname: Golubic
mesh_terms: D000818:Animals; D037421:Anthozoa; D001483:Base Sequence; D018441:Biofilms / Q000145:classification*; D000458:Cyanobacteria / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D017753:Ecosystem; D004784:Environmental Monitoring; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000378:metabolism; D010802:Phylogeny; D012623:Seawater / Q000737:chemistry / Q000382:microbiology
chemical_list: D009591:Nitrogenase; D009584:Nitrogen
references.citation: Proc Natl Acad Sci U S A. 1967 Nov;58(5):2071-8
references.pmid: 5237501
references.citation: FEMS Microbiol Lett. 2006 Jul;260(2):171-7
references.pmid: 16842341
references.citation: Res Microbiol. 2003 Apr;154(3):157-64
references.pmid: 12706503
references.citation: Microbiology (Reading). 2002 Feb;148(Pt 2):481-496
references.pmid: 11832512
references.citation: Appl Environ Microbiol. 1996 Mar;62(3):986-93
references.pmid: 16535283
references.citation: Appl Environ Microbiol. 1983 Apr;45(4):1331-7
references.pmid: 16346272
references.citation: New Phytol. 1998 Nov;140(3):531-538
references.pmid: 33862883
references.citation: Ambio. 2002 Dec;31(7-8):602-5
references.pmid: 12572829
references.citation: J Bacteriol. 1988 Aug;170(8):3584-92
references.pmid: 3136142
references.citation: Nature. 2003 Oct 2;425(6957):504-7
references.pmid: 14523445
references.citation: Nucleic Acids Res. 1994 Nov 11;22(22):4673-80
references.pmid: 7984417
references.citation: Biomol Eng. 2003 Jul;20(4-6):191-7
references.pmid: 12919797
references.citation: Int J Syst Evol Microbiol. 2005 Mar;55(Pt 2):555-568
references.pmid: 15774625