With contributions from:
Sara Kleindienst, Kim Hunter, Melitza Crespo-Medina,
Sairah Malkin, Matt Saxton & Ryan Sibert (Univ. Georgia)
Sharon Grim & Mitch Sogin (Marine Biological Laboratory)
How$an$offshore$oceanic$ecosystem$responded$to$extreme$perturba6on:$$
!
The!2010!Gulf!of!Mexico!BP/Deepwater!Horizon!oil!well!blowout.!Samantha$Joye$
Dis6nguished$Professor$of$Marine$Sciences$Project$Director:$Ecosystem$Impacts$of$Oil$and$Gas$Inputs$to$the$Gulf$(GoMRI)$
Department$of$Marine$Sciences,$University$of$Georgia$
EKmail:[email protected]$$
Gulf of Mexico - a petroleum basin - salt tectonics drives gas and oil seepage
Harry Roberts, LSU
ECOGIG Video Caroline Johannson
Ian MacDonald
Map: Ian MacDonald (FSU)
Human oil extraction short circuits the “geologic” C cycle
• natural oil release <2,600 bbl/day >50 Million reservoir Turnover time
www.globe.gov/projects/carbon
Map: Ian MacDonald (FSU)
Human oil extraction short circuits the “geologic” C cycle
• natural oil release <2,600 bbl/day • ~US oil use ~19,110,000 bbl/day •global oil use ~64,000,000 bbl/day ~<1000 yr TT
Humans are mining a resource that took 100’s of millions of years to produce, and which naturally cycles back into the active C cycle on a similar time scale, and releasing it directly to the Earth’s atmosphere in the blink of a geologic eye
www.globe.gov/projects/carbon
Natural seeps • >20,000 documented seeps • ~1,000 surface oil slicks • natural release ~ 2,600 BOPD • diffuse, slow, variable in time/space
Natural seepage vs. the Macondo Blowout
Macondo Blowout • point source injection (jet) • at least 57,000, up to 70,000, BOPD • 84 days @ 1500m water depth • 460,539 – 690,176 tonnes of oil + gas; ~50% entrained in deepwater
Still, offshore drilling will continue
Gulf UDWD - 2000-3000 m water depth - 46 billion BOE (OCS Report MMS 2100-22)
Maximal surface oil cover (early June)
Major points
• natural hydrocarbon degrading communities are limited by biological
and environmental factors
• impact of dispersants
on microbial community composition and oil
biodegradation activity
• microbial oil snow formation and sedimentation
Head et al. 2006 Nat Rev Microbiol.
Kleindienst, Paul & Joye, Nat. Rev. Microbiol. 2015
Hydrocarbon metabolism is mutualistic & synergistic *regulation is complex and poorly understood*
What is the impact of chemical dispersants on microbial hydrocarbon degradation & community
composition?
Dispersants drive microbial community evolution
* * * *
Potential key players involved into hydrocarbon degradation Dispersant treatments = Colwellia spp. Oil only = Marinobacter spp. Kleindienst et al. in press
Oligotypes
Notably, dispersant addition selected for specific
oligotypes of Colwellia
That was not the case for Marinobacter or Cycloclasticus
(or Oceaniserpentilla)
Do these different microbial communities function
similarly?
Is activity stimulated by dispersant addition?
d
o
Kleindienst et al. in press
**if not visible, error bars are indistinguishable from bar
Degradation rates of alkanes (~hexadecane) and polycyclic aromatic hydrocarbons (~napthalene) were
reduced in the presence of dispersants
Kleindienst et al. in press
Microbial “oil snow”
dual CARD-FISH hybridizations using probes targeting Bacteria (green; o-t) and Alteromonadales (incl. Marinobacter) (red; o-t).
! Nutrients + oil + dispersants (11, 15 days)
! Dispersants only (“lasso” after 15 days)
! oil (g & h ), dispersed oil (i)
(a) (b) (c)
(d) (e) (f)
(g) (h) (i)
(j) (n) (m) (l) (k)
(o) (p) (q)
(r) (s) (t)
10 µm
5 µm
10 µm
500 µm
500 µm
500 µm
Seafloor “footprint” of oil snow sedimentation event
Chanton et al. 2014 ES&T
2-15% of discharged oil = 8 to 96 × 103 tonnes oil or 8 to 96 Gg of oil * covering a seafloor area of 3,000 to 8,400 km2 (avg. thickness ~1cm) *
Similar microbial “fingerprint”
Joye et al. 2015 Science
What was the fate of Macondo oil?
Conclusions • Chemical dispersant addition altered
microbial community composition and reduced oil degradation rates
Conclusions • Chemical dispersant addition altered microbial community composition and
reduced oil degradation rates
• Chemical dispersant addition also led to the highest rates of marine oil snow formation
Conclusions • Chemical dispersant addition altered microbial community composition and
reduced oil degradation rates • Chemical dispersant addition also led to the highest rates of marine oil snow
formation
• Sedimentation of weathered oil-containing marine snow was a considerable fate for Macondo oil; this process was significantly stimulated by microbial processes
Conclusions • Chemical dispersant addition altered microbial community composition and
reduced oil degradation rates • Chemical dispersant addition also led to the highest rates of marine oil snow
formation • Sedimentation of weathered oil-containing marine snow was a considerable
fate for Macondo oil; this process was significantly stimulated by microbial processes
• The Gulf system is resilient; some of response efforts may have impaired that resiliency
Thank You