Woods Hole Oceanographic Insitution 2013 CMORE SUMMER COURSE Student symposium 1st June 2013, Honolulu, HI Investigating Trichodesmium ecophysiology and the factors determining niche differentiation in the North Atlantic Ocean Mónica Rouco Woods Hole Oceanographic Insitution Dr. Sonya Dyhrman´s lab Photo: Abby Heithoff

DIAZOTROPHIC CYANOBACTERIA Tropical and subtropical waters Photos: A. Heithoff; E. Orchard

FACTORS INFLUENCING TRICHODESMIUM N2FIXATION &GROWTH LIGHT INTENSITY (Breitbarth et al. 2008. Mar Ecol Prog Ser) TEMPERATURE (Breitbarth et al. 2007 Biogeosciences; Hutchins et al. 2008). MIX LAYER DEPTH/VERTICAL STRATRIFICATION (Karl et al. (2001); Sañudo-Wilhelmy et al. (2001)). NUTRIENTS and TRACE METALS IRON (Moore et al. 2009. Nature Geoscience) PHOSPHORUS (Sañudo-Wilhelmy et al. 2001, Nature; Moore et al. 2004, GBC; Hynes et al. 2009) Photo: E. Orchard

COLONY MORPHOLOGY B A C Raft/tuft Puff Bowtie Hynes et al. (2012) J. Phycol. 48, 196–210 (2012)

TRICHODESMIUM SPECIES Trichodesmium contortum Trichodesmium erythraeum Trichodesmium tenue Trichodesmium thiebautii Trichodesmium spiralis Trichodesmium hildebrandtii Overlapping Characteristics Clade I (erythraeum like) Clade II (thebautti like) Hynes et al. (2012) J. Phycol

FACTORS INFLUENCING TRICHODESMIUM N2FIXATION &GROWTH LIGHT INTENSITY (Breitbarth et al. 2008. Mar Ecol Prog Ser) TEMPERATURE (Breitbarth et al. 2007 Biogeosciences; Hutchins et al. 2008). MIX LAYER DEPTH/VERTICAL STRATRIFICATION (Karl et al. (2001); Sañudo-Wilhelmy et al. (2001)). NUTRIENTS and TRACE METALS IRON (Moore et al. 2009. Nature Geoscience) PHOSPHORUS (Sañudo-Wilhelmy et al. 2001, Nature; Moore et al. 2004, GBC; Hynes et al. 2009) INTRINSIC ABILITIES Photo: E. Orchard

MOTIVATION FOR THIS PROJECT C.S. Davis and D. McGillicuddy (2006) Science 312, 1517 Unexpected vertical Trichodesmium spp. distribution More uniform than previously thought Unexpected vertical Trichodesmium spp. distribution More uniform than previously thought

QUESTIONS... Is the vertical distribution of Trichodesmium spp. in the high abundance region of the western tropical North Atlantic similar to that reported in Davis and McGillicuddy (2006)? Are the deep populations of Trichodesmium spp. actively fixing nitrogen? Spatial and vertical clade distribution (qPCR) Niche differentiation. Physiological ecology of surface v subsurface populations. RNA Seq (Metatranscriptomics).

OC471 Spring 2010 Map section: Elise Olson

Trichodesmium abundance: VPR MEASURED PARAMETERS (OC471) Trichodesmium abundance: VPR (Elise Olson & Dennis McGillicudy, Cabell Davis) N2 fixation rates (Acetylene reduction assay): Surface (5-15m) Subsurface (below predicted MLD) Clade distribution: DNA (0,20,40,60,80m) qPCR High-throughput transcriptome sequencing: RNA

TRICHODESMIUM VERTICAL PATTERNS (VPR) VPR (Elise Olson & Dennis McGillicuddy) There is a vertical distribution of Trichodesmium populations. Rafts are associated with the surface and puffs are unevenly distributed.

Subsurface populations are actively fixing N2 N2 FIXATION Average SURFACE N2 FIX : 231.1 ± 59.6 µmol N h-1 molC-1 Average SUBSURFACE N2 FIX: 103.1 ± 48.6 µmol N h-1 molC-1 Subsurface populations are actively fixing N2

q-PCR based methodology (DNA) ADAPTIVE ECOTYPES SEGREGATED IN THE WATER COLUMN q-PCR based methodology (DNA) 6 species Trichodesmium contortum Trichodesmium erythraeum Trichodesmium tenue Trichodesmium thiebautii Trichodesmium spiralis Trichodesmium hildebrandtii Clade I Clade II

Clade I(erythraeum like) ADAPTIVE ECOTYPES SEGREGATED IN THE WATER COLUMN q-PCR based methodology (DNA) 6 species Trichodesmium contortum Trichodesmium erythraeum (IMS 101) Trichodesmium tenue Trichodesmium thiebautii Trichodesmium spiralis Trichodesmium hildebrandtii Clade I(erythraeum like) Clade II (thebautii like)

Clade I (erythraeum like) Clade II (thebautii like) ADAPTIVE ECOTYPES SEGREGATED IN THE WATER COLUMN q-PCR based methodology (DNA) 6 species Trichodesmium contortum Trichodesmium erythraeum (IMS 101) Trichodesmium tenue Trichodesmium thiebautii (VI-I) Trichodesmium spiralis Trichodesmium hildebrandtii Clade I (erythraeum like) Clade II (thebautii like)

Clade specific primers ADAPTIVE ECOTYPES SEGREGATED IN THE WATER COLUMN q-PCR rnpB gene (RNase P) Clade specific primers Chappel & Webb (2010) Environmental Microbiology STANDARD CURVE FILTERS ,DILUTIONS Cell concentration (total filament lengths + average cell length) DNA extraction qPCR

thebautii like populations SPECIES SEGREGATION IN THE WATER COLUMN (OC471) 5 8 2 3 4 6 7 9/16   10 15 11 13/14 12 5 8 2 3 4 6 7 9/16   10 15 11 13/14 12 91-100% thebautii like populations

(Salinity, Temperature) SPECIES SEGREGATION IN THE WATER COLUMN (OC471) 5 8 2 3 4 6 7 9/16   10 15 11 13/14 12 5 8 2 3 4 6 7 9/16   10 15 11 13/14 12 PCA (Salinity, Temperature)

SPECIES SEGREGATION IN THE WATER COLUMN (HOE-DYLAN) Cryptic bloom of erythraeum?

CONCLUSIONS There is a vertical distribution of Trichodesmium populations. Rafts are associated with the surface and puffs are unevenly distributed. Subsurface populations are actively fixing nitrogen but yield lower rates than those observed by surface populations. 91-100% of the Trichodesmium populations along the OC471 cruise transect in the North Atlantic Ocean corresponded to thebautii like populations. Niche differentiation

IN PROCESS… High-throughput metatranscriptome sequencing to examine transcriptional patterns and relative gene expression in order to understand physiological ecology of surface v subsurface populations (already extracted and waiting for the sequences to start HAVING FUN!) Columbia genome center

Thank You! Sonya Dyhrman Abby Heithoff Dyhrman´s lab: Harriet Alexander Hanna Jon-Warren Sheean Haley Julia Diaz Louie Wurch Solange Duhamel Elise Olson Dennis McGillicuddy Thank You! FUNDING: Fundación Ramón Areces (SPAIN). C-MORE National Science Fundation.

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