Enhancemen o ni ogen ixa ion a es by unicellula
diazo ophs e sus T ichodesmium a e a dus
deposi ion e en in he Cana y Islands
Ma Bena ides
•Reduc ion o a mosphe ic ni ogen o ammonium N2NH4+
•Diazo ophic o ganisms (diazo = ni ogen, ophykos = nu i ion)
Cyanobac e ia, Bac e ia, A chaea
•N2 ixa ion uels up o 50% o open ocean p ima y p oduc ion
(Capone e al., 2005)
•Ni ogenaseni H gene
•Diazo ophs limi ed by Fe and P
In oduc ion
Unicellula cyanobac e ia
Eg. Cyano hece sp.
Symbio ic cyanobac e ia
Eg. Richelia in acellula is
Colonial cyanobac e ia
Eg. T ichodesmium hiebau ii
Riemann e al., 2010
In oduc ion
UCYN-A
UCYN-B
Moisande e al., 2010
•T ichodesmium only appea s in
opical and sub opical a eas
•Wide dis ibu ion o he ni H gene
bu …
•Lack o N2 ixa ion da a
The impo ance o unicellula diazo ophs
In oduc ion
Cana y Cu en
•S ong su ace hea ing h oughou he yea
•Quasi-pe manen he moclineoligo ophic wa e s
•Mixing Janua y-Ma ch‘la e win e bloom’
•Dus deposi ionP and Fe
A ís egui e al., 2009
•S a ion 2
Sampling each 15 days / 3 mon hs
LuCIFe P ojec
Objec i es
• Sho - e m a iabili y o N2 ixa ion ac i i y in Cana y Cu en wa e s
• In luence o Saha an dus deposi ion on diazo ophic ac i i y and
di e si y

N2 ixa ion
•Ace ylene Reduc ion Assay (ARA) (S al, 1988)
H−CΞC−HNΞN Con e sion ac o C2H2:N2= 4:1
•Su ace wa e (Niskin 30 L)
•On-deck incuba ions (ligh /da k)
Me hods
20x 10x
Abundance o T ichodesmium sp.
•Plank on ne 50 μm
•Ve ical cas s o 100 m
•ARA >50 µm
>50 µm N2 ixa ion a es = T ichodesmium N2 ixa ion a es
•Co ela ions be ween >50 µm N2 ixa ion a es and T ichodesmium abundance
2=0.86 (ligh ) 2=0.69 (da k) p<0.05
Su ace seawa e N2 ixa ion a es = Unicellula diazo oph N2 ixa ion a es
•Low p obabili y o ca ching T ichodesmium wi h Niskin bo les when i s abundance is low
(Chang, 2000)
Unicellula diazo oph abundance
Ty amide Signal Ampli ica ion – Fluo escen In Si u Hyb idiza ion (TSA-FISH)
Me hods
•Fil a e seawa e on PC il e s
•P obe Ni o821 ni H gene
•Classi ica ion
Leica DM 2500
Size Type
<1 µm Small F ee-li ing
>1 - <3 µm Medium A ached o o ganic
ma e
>3 µm La ge Symbion
Me hods
Dus deposi ion and composi ion
•Ae osol Op ical Dep hGio anni NASA
•PM10, PM2.5Gobie no de Cana ias Calidad del Ai e
•Me al analysis
Hyd og aphy and Chl a
•CTD SBE 25
•Tu ne AU-10
Fluo ome e
Resul s & Discussion
Tempe a u e, MLD, Chl a, nu ien s
•Highe empe a u es han p e ious yea s
•S a i ica ion
•Lowe Chl a
•Low nu ien concen a ions
No clea ‘la e win e bloom’
G acias!