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

Caron, Countway, Jones, Kim & Schnetzer, 2012, An Rev Mar Sci

3. range in functional modes

Caron, Countway, Jones, Kim & Schnetzer, 2012, An Rev Mar Sci

pCO2 pCO2

Temp Temp

Light Light

Nutrients Nutrients Salinity Salinity

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

pCO2 and community structure

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