TY - JOUR
T1 - Is dinitrogen fixation significant in the Levantine Basin, East Mediterranean Sea?
AU - Yogev, Tali
AU - Rahav, Eyal
AU - Bar-Zeev, Edo
AU - Man-Aharonovich, Dikla
AU - Stambler, Noga
AU - Kress, Nurit
AU - Béjà, Oded
AU - Mulholland, Margaret R.
AU - Herut, Barak
AU - Berman-Frank, Ilana
PY - 2011/4
Y1 - 2011/4
N2 - We report N2 fixation rates measured from two stations monitored monthly off the Mediterranean coast of Israel during 2006 and 2007, and along a transect from Israel to Crete in September 2008. Analyses of time-series data revealed expression of nifH genes from diazotrophs in nifH clusters I and II, including cyanobacterial bloom-formers Trichodesmium and diatom-Richelia intracellularis associations. However, nifH gene abundance and rates of N2 fixation were very low in all size fractions measured (>0.7μm). Volumetric 15N uptake ranged from below detection (~36% of >300 samples) to a high of 0.3nmolNl-1d-1 and did not vary distinctly with depth or season. Areal N2 fixation averaged ~1 to 4μmolNm-2d-1 and contributed only ~1% and 2% of new production and ~0.25% and 0.5% of primary production for the mixed (winter) and stratified (spring-fall) periods respectively. N2 fixation rates along the 2008 east-west transect were also extremely low (0-0.04nmolNl-1d-1, integrated average 2.6μmolNm-2d-1) with 37% of samples below detection and no discernable difference between stations. We demonstrate that diazotrophy and N2 fixation contribute only a minor amount of new N to the P impoverished eastern Mediterranean Sea.
AB - We report N2 fixation rates measured from two stations monitored monthly off the Mediterranean coast of Israel during 2006 and 2007, and along a transect from Israel to Crete in September 2008. Analyses of time-series data revealed expression of nifH genes from diazotrophs in nifH clusters I and II, including cyanobacterial bloom-formers Trichodesmium and diatom-Richelia intracellularis associations. However, nifH gene abundance and rates of N2 fixation were very low in all size fractions measured (>0.7μm). Volumetric 15N uptake ranged from below detection (~36% of >300 samples) to a high of 0.3nmolNl-1d-1 and did not vary distinctly with depth or season. Areal N2 fixation averaged ~1 to 4μmolNm-2d-1 and contributed only ~1% and 2% of new production and ~0.25% and 0.5% of primary production for the mixed (winter) and stratified (spring-fall) periods respectively. N2 fixation rates along the 2008 east-west transect were also extremely low (0-0.04nmolNl-1d-1, integrated average 2.6μmolNm-2d-1) with 37% of samples below detection and no discernable difference between stations. We demonstrate that diazotrophy and N2 fixation contribute only a minor amount of new N to the P impoverished eastern Mediterranean Sea.
UR - http://www.scopus.com/inward/record.url?scp=79951589736&partnerID=8YFLogxK
U2 - 10.1111/j.1462-2920.2010.02402.x
DO - 10.1111/j.1462-2920.2010.02402.x
M3 - Article
C2 - 21244595
AN - SCOPUS:79951589736
SN - 1462-2912
VL - 13
SP - 854
EP - 871
JO - Environmental Microbiology
JF - Environmental Microbiology
IS - 4
ER -