deciphering the effects of oa on microbial assemblage...
TRANSCRIPT
In collaboration with (in alphabetical order) David A. Caron, Fei Xue Fu, David A. Hutchins, Alle A. Y. Lie
and Avery O. Tatters (USC)
Astrid Schnetzer
Marine Plankton Ecology Dept. of Marine, Earth and Atmospheric Sciences
North Carolina State University
Deciphering the effects of OA on microbial assemblage structure and community function
Outline
1) “The OA wish list”
2) How to study OA impacts on single species and/or mixed communities - things to consider when studying microbes
3) Beginning to decipher connections 4) Where from here?
© Schnetzer
Protists: phytoplankton and protozoa
Outline
1) “The OA wish list”
2) How to study OA impacts on single species and/or mixed communities - things to consider when studying microbes
3) Beginning to decipher connections 4) Where from here?
© Schnetzer
Protists: phytoplankton and protozoa
Outline
1) “The OA wish list”
2) How to study OA impacts on single species and/or mixed communities - things to consider when studying microbes
3) Beginning to decipher connections 4) Where from here?
© Schnetzer
Protists: phytoplankton and protozoa
Outline
1) “The OA wish list”
2) How to study OA impacts on single species and/or mixed communities - things to consider when studying microbes
3) Beginning to decipher connections 4) Where from here?
© Schnetzer
Protists: phytoplankton and protozoa
1) The OA wish list (knowledge gaps):
from single species to natural (mixed) communities
from pCO2 changes to multifactorial studies
from single to multiple trophic levels
from community structure to community function
from short-term incubation to long-term prediction (acclimation vs.
adaptation)
© Schnetzer
2) When studying protistan assemblages
1. range in size
2. range in abundances
Image credits D. Caron (USC) and Schnetzer (NCSU)
3. range in functional modes
Genetic Approaches to study microbial communities
Species List
Rel
ativ
e Abu
ndan
ce
Caron, Countway, Jones, Kim & Schnetzer, 2012, An Rev Mar Sci
direct microscopy
culture
DNA fragment analyses
single gene cloning and sequencing
high throughput sequencing
common rare
- Assess “entire” community - Process high sample number - Begin to account for rare members
Genetic Approaches to study microbial communities
new lineages and taxa are still being discovered complex spatiotemporal dynamics NGS has yet to penetrate Rare Biosphere
Ecological importance of rare members?
Link to functional genomics!
- Assess “entire” community - Process high sample number - Begin to account for rare members
Tatters A.O., Schnetzer A., Fu F., Lie A, David A. Caron and David A. Hutchins (2013) Evolution 67: 1879-1891
pCO2 and community structure 3) Decipher Connections
2 week incubation 4 mo
8 mo 12 mo
Cluster-diagram showing Bray–Curtis similarity for the dinoflagellate assemblages analyzed after the initial 2-week natural community pCO2 incubation, after 4, 8 and 12 months of growth at elevated pCO2.
With increased acclimation period affect of differing pCO2 competition levels on overall community structure weakened
Tatters, Schnetzer et al., (2013) Evolution 67: 1879-1891
Need to complement culture studies with studies that use fresh isolates! (genetic variance)
low medium high pCO2
grow
th (d
iv d
ay-1
)
Higher species-specific growth rates in mixed assemblages versus unialgal culture (independent of acclimation period under constant abiotic settings)
Unialgal – 8mo
Mixed – 12mo
Mixed – 0mo
Tatters, Schnetzer et al., (2013) Evolution 67: 1879-1891
Species Interactions? allelopathy mixotrophy facilitation……..
pCO2 and physiology
Multifactorial studies pCO2 & temperature • primary driver temperature with secondary effects due to CO2
• shifts in coastal diatom composition from New Zealand - Tatters et al., 2013 • dominance of diatoms vs. nanophytoplankton from Bering Sea - Hare et al., 2007
pCO2 & nutrient availability • synergistic effects of elevated CO2 with nutrient availability
• growth and toxin production in varying harmful algal taxa - Fu et al., 2012 • N source and CO2 drive growth in E. huxleyi - Lefebvre et al., 2011
pCO2 & light & iron availability • each combination of the three factors affected diatom community structure
• elevated CO2 caused shift towards large centric diatom instead of pennate forms - Feng et al., 2010
…………………………….
GRR = Growth Rate Response under elevated / ambient pCO2
GRR decrease
GRR increase
Modeling / Predictions
BM increase BM decrease
GRR increase
GRR decrease
physical changes only - pCO2 kept at 1860
pCO2 only – physical changes kept at 1860
David A. Hutchins et al., Oceanography (2009)
Stoichiometry
C:N and C:P ratios tend to increase or are unaffected
More complex as entire plankton community is considered
Need for local and regime-specific studies
Hutchins and Caron (2013), J Plankt Res 35(2): 235–252
Direct effects Indirect effects Microzooplankton
Top-down Controls
Changed total grazer impact
Altered species composition
Altered trophic Coupling
Bottom –up controls
Changed primary productivity
Altered C:N:P
Altered taxonomic composition
Changed microzooplankton grazer impact
CO2
pH Temperature Light Nutrient Availability
CO2
O2
pH
Light
Temperature
Food Web Transfer
Direct chemical and physical effects Altered phenology Polar migration Changed prey availability
Scaling Up
Primary Producers
Grazers
Riebesell et al., (2013) Biogeosciences, 10, 5619–5626, 2013
Pelagic Ecosystem CO2 Enrichment (PeECE) studies
Riebesell et al., (2013) Biogeosciences, 10, 5619–5626, 2013
• No incorporation of additional CO2 into phytoplankton BM
• No response in bacteria to increased DOM due to nutrient limitation
• Decreased grazing
• Pico-and nanophytoplankton BM increases,
• Larger microphytoplantkon decreases
• Elevated DOM results in microbial response
• Grazer response
• Decrease in sinking flux
Filling in the knowledge gaps
from pCO2 changes to multifactorial studies from single to multiple trophic levels
from community structure to community function from short-term incubation to long-term
prediction (acclimation vs. adaptation)
© Schnetzer
I. Incorporation of genetic approaches to determine structure and function for single species and mixed assemblages
from single species to natural (mixed) communities
4) Where from here?
Filling in the knowledge gaps
from pCO2 changes to multifactorial studies from single to multiple trophic levels
from community structure to community function from short-term incubation to long-term
prediction (acclimation vs. adaptation)
© Schnetzer
I. Incorporation of genetic approaches to determine structure and function for single species and mixed assemblages
from single species to natural (mixed) communities
4) Where from here?
II. Combine suite of lab and mesocosm experiments to examine change over environmental gradients
offshore estuarine NC Florida
standardize response parameters for regional biogeochemical and ecosystem models
System-inherent environmental drivers, there regime-specific variability and their associated biological communities - Nutrient availability - Light - Salinity - …………….
….. SOCAN will set regional priorities for monitoring and research;
3) Where from here?
SouthEast Acidification Laboratories (SEALs) to study the effects of OA on marine planktonic communities and biogeochemical cycling: from offshore to estuarine systems and from North Carolina to Florida
Friday Harbor, UW From: Ocean Acidification: A National Strategy to Meet the Challenges of a Changing Ocean, NRC, 2010
….. SOCAN will set regional priorities for monitoring and research;
3) Where from here?
SouthEast Acidification Laboratories (SEALs) to study the effects of OA on marine planktonic communities and biogeochemical cycling: from offshore to estuarine systems and from North Carolina to Florida
• Leverage by building on existing knowledge of key organisms, communities and pertinent scales in SOCAN region.
• Create a platform to incorporate regional stakeholders and ecosystem management entities in research design (SOCAN network in action).
• Create regional “OA hubs” to conduct OA workshops, train proper technique (i.e. manipulation/monitoring of seawater carbonate chemistry), organize regional meetings and interdisciplinary symposia.
• Create “Hot Spots” for multidisciplinary, regional research efforts that allow to ask system-level questions.
Trees sneezing.
Really? No, but the truth is complicated.
The trees are really sneezing
today!
Dad what causes wind?
and…. prepare me (us) to better answer complex OA questions
By Bill Waterson