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Workshop 2

The impact of anthropogenic perturbations on open ocean carbon sequestration via the dissolved and particulate phases of the biological carbon pump

Anthropogenic impacts such as elevated pCO2 and eutrophication threaten the structure and functioning of marine ecosystem as well as the role of the ocean in the global carbon cycle. The ocean absorbs approximately one-third of the CO2 released by fossil fuel combustion (Doney et al., 2004) raising the question of the potential of the ocean for long-term net carbon sequestration. While sinking-particle-based carbon sequestration (the biological pump; BP) has been extensively studied, the biogeochemical behaviour of dissolved organic matter (DOM) - and its potential role in climatically significant carbon sequestration in the dissolved phase (the microbial carbon pump, MCP; Jiao et al., 2010)  - is largely unexplored. Furthermore, while the impacts of changes in thermal stratification on the BP have been discussed at an earlier IMBIZO workshop, the effects of climate change and anthropogenic perturbations such as eutrophication and ocean acidification on the MCP and BP, remain poorly understood.

The BP and the MCP operate simultaneously and interactively but their responses to environmental conditions may be regulated differently (e.g. in shallow coastal waters versus deep waters; oligotrophic oceanic waters versus eutrophic waters) but these regulatory mechanisms have not been examined - particularly for MCP-based carbon sequestration. Further, it is not known whether the BP and the MCP would interact to enhance or reduce their individual effects. A potential effect of eutrophication, or nutrient addition in general, (in addition to algal blooms and hypoxia) may be a shift in the balance of carbon sequestration via the MCP and the BP. Predictions of any marine carbon cycle manipulations should therefore take into account such potential interactions between the BP and the MCP. For example, it is possible that reducing the use of chemical fertilization on the land could lead to an enhancement of the MCP as a carbon sink in eutrophic coastal waters (Jiao et al., 2010). Fishing practices are further changing the structure of the marine food web and the dominant pathways of carbon flow in marine ecosystems, so an integrative consideration of the BP and the MCP could help identify practices conducive to enhanced carbon sequestration. Such comprehensive ecosystem based optimizations (rather than piecemeal manipulations) of the regulation of the ocean carbon cycle may benefit from emerging knowledge of previously unrecognized carbon sinks, notably the MCP.

Processes, which are deemed to interfere with the MCP and BP and their interaction, in the open oceans, and which may be considered for discussion during the workshop comprise (non-exclusively) nutrient addition from land via rivers and the atmosphere, intentional and unintentional addition of trace elements, and ocean acidification, as well as comparisons with environments having naturally accentuated occurrences of anthropogenic species affecting the BP and the MCP.

This workshop will attract scientists from multiple disciplines including microbial ecologists, biogeochemists, organic chemists, climate scientists, fisheries scientists and economists to exchange ideas and devise strategies to integrate the MCP into the concepts and models of carbon sequestration in the ocean’s and the global carbon cycle. The recognition of the significance of MCP-based carbon sequestration and its interaction with the BP will deepen our current knowledge for predicting the outcomes of geo-engineering of the ocean carbon cycle (e.g. by iron fertilization etc.). Of considerable interest is the possibility that the integration of MCP processes to better understand the ocean carbon cycle may lead to win-win strategies for enhanced carbon sequestration. IMBIZO is an excellent opportunity to discuss future natural and social science research needs to integrate the MCP to better understand the marine carbon cycle, as well as multi-disciplinary brainstorming on “eco-engineering” as system-based optimization of multiple desirable environmental goals.

Workshop 2 Conveners

Nianzhi Jiao (Xiamen University, China)

Farooq Azam (Scripps Institute for Oceanography, USA)

Carol Robinson (University of East Anglia, UK)

Helmuth Thomas (Dalhousie University, Canada)

Workshop Presentations

DAY 1 - Monday 28 January

08:00-09:00 IMBIZO llI Registration

Welcome – Eileen Hofmann, Alida Bundy and Kon-Kee Liu


Workshop 1 Keynote presentation: Ocean hypoxia from physics to fish – Curtis Deutsch

10:00-10:45 Workshop 1 Keynote presentation: Nutrients, hypoxia and fisheries: lessons about multiple stressors from the Chesapeake and beyond – Denise Breitburg
10:45-11:15 Coffee break
11:15-12:00 Workshop 2 Keynote presentation: Microbial carbon pump and ecosystem connectivity – Farooq Azam

Workshop 3 Keynote presentation: “ADApT or Die”: Finding methodologies to secure the livelihoods and food security for fisheries dependent communities around the world – Moeniba Isaacs

12:45-13:45 Lunch
13:45-14:20 Workshop 2 overview and objectives – processing of DOC, interactions between MCP and BP, perturbations and links to humanity and large scale C cycling – Farooq Azam, Nianzhi Jiao, Carol Robinson and Helmuth Thomas

Session 1.a - Chair: Farooq Azam

Nature of DOC

14:20-14:50 Ageing of marine dissolved organic matter: A molecular perspective - Boris Koch
14:50-15:10 Probing the microbial carbon pump in proterozoic oceans - Chao Li
15:10-15:30 Production of exopolysaccharide by marine bacteria - Zilian Zhang
15:30-16:00 Coffee break

Session 1.b - Chair: Carol Robinson

Microbial processing of DOC and genetic diversity

16:00-16:20 Prokaryotic autotrophy in the meso- and bathypelagic Atlantic Ocean - Gerhard Herndl
16:20-16:40 Deep-sea prokaryotic heterotrophic activity in the world’s oceans – Thomas Reinthaler
16:40-17:00 Understanding controls of diel patterns of biological CO2 fixation in the North Atlantic Ocean - Helmuth Thomas

Plenary session discussion – Chair KK Liu, Rapporteur: Karen Wishner

How do biogeochemistry and ecosystems interact in response to natural or man-induced forcing in continental margins and how can such knowledge forge better management of the marine realm?

18:00-19:30 Ice breaker and poster session

DAY 2 - Tuesday 29 January


Session 1.c – Chair: Gerhard Herndl

Microbial processing of DOC and genetic diversity

09:00-09:10 Recap of sessions 1a and 1b and the session 1 objectives – Farooq Azam
09:10-09:30 MCP, Microbial respiration and ecological efficiency in estuarine ecosystems - Hongyue Dang

The meaning of diversity for understanding the microbial carbon pump in the oceans - David Kirchman

09:50-10:10 Distribution and function of genes related to microbial dissolved organic matter utilization - Kai Tang
10:10-10:30 Diversity of nasA genes in the global oceans - Xuexia Jiang
10:30-11:00 Coffee break

Synthesis 1 - Chair: Carol Robinson

Microbial processing of DOC

12:30-13:30 Lunch

Session 2.a - Chair: Nianzhi Jiao

Interactions between MCP and BP

13:30-13:50 Potential effects of ocean warming on the biological and microbial carbon pumps - Louis Legendre
13:50-14:10 Autotrophic and heterotrophic responses to iron and nutrient enrichment in the western Pacific Ocean - Qian Li
14:10-14:30 Microbial loop and carbon export in the subtropical ocean – Susanne Neuer
14:30-15:00 The ecological effects of marine microbial aggregates on DOC and POC - Xiaoxue Wang
15:00-15:30 Coffee break

Session 2.b - Chair: Victor Smetacek

Interactions between MCP and BP


The rise and dominance of mixotrophic protists in a changing world; redefining the functionality of the biological and microbial carbon pumps - Aditee Mitra

15:50-16:10 Sensitivity of the ocean biological pump to parameterizations of the recycling matter - Anastasia Romanou

Carbon export algorithm advancement in models - Çağlar Yumruktepe

16:30-17:00 Discussion – Chair: Carol Robinson

Plenary session discussion – Chair: Helmuth Thomas

How may current understanding of deep ocean processes translate to better assessment and stewardship of fundamental ecological services that deep oceans provide?

18:00-20:00 Poster session

DAY 3 - Wednesday 30 January


Session 2.c - Chair: Farooq Azam

Response to anthropogenic perturbation

09:00-09:10 Recap sessions 2a and 2b and the Session 2 objectives (Chair: Nianzhi Jiao)
09:10-09:30 Responses of the “Biological pump” and the “Microbial carbon pump” to nutrient perturbations in natural and anthropogenic scenarios - Nianzhi Jiao
09:30-09:50 Possible changes in the dynamics of particulate carbon sequestration in the open ocean associated to anthropogenic perturbations of the environment - Juan Carlos Miquel  
09:50-10:10 Microbiological and photochemical transformation of organic carbon during an in situ iron and phosphate addition experiment - Carol Robinson
10:10-10:30 The effect of nitrogen and phosphorus on CDOM generated by bacteria - Rui Ren
10:30-11:00 Coffee break
11:00-12:00 Session 2.d – Chair: David Kirchman: Response to anthropogenic perturbation

On exploiting the potential of ocean iron fertilization experiments for testing hypotheses on the carbon pump and ecosystem restoration - Victor Smetacek


Response of bacterioplankton community structure to an artificial gradient of pCO2 in the Arctic Ocean - Rui Zhang

Rui Zhang.pdf 2.53 MB

Will ocean acidification or eutrophication impact bacterioplankton diversity and carbon processing in the coastal Mediterranean Sea - Federico Baltar

12:00-12:30 Discussion
12:30-13:30 Lunch

Session 3.a – Chair: Helmuth Thomas

Large temporal and spatial scale dynamics and links to humanity


The global alliance of continuous plankton recorder surveys (GACS): a tool for multi-decadal monitoring the ocean’s response to human and other global change processes - Peter Burkill


Role of meso-scale eddies on the variability of biogenic flux in the northern and central Bay of Bengal – P.J. Vidya

P.J. Vidya.pdf 2.55 MB
14:10-14:30 Effects of anticyclonic eddy from the Kuroshio on the winter phytoplankton bloom in the South China Sea: An eddy-resolving physical-biological model study - Yoshikazu Sasai

The influence of the Indian Ocean dipole on interannual variations in phytoplankton size structure as revealed by earth observation - Nick Hardman-Mountford

15:00-15:30 Coffee break

Studying oxygen minimum zones in the Northern Indian Ocean using Argo-Oxygen data - Satya Prakash


Synthesis 2 - Chair: Nianzhi Jiao

MCP - BP interactions: Response to perturbations and large scale dynamics


Plenary session discussion – Chair: Alida Bundy

How can natural and social scientists optimize their cooperation to achieve usable and integrated knowledge and understanding to support policy making and form viable feedback loops between the natural system and human society?

19:15-22:30 IMBIZO lll dinner – Hawaii Beach Restaurant

DAY 4 - Thursday 31 January


Session 4: Workshop 2 synthesis - Chairs: Helmuth Thomas, Carol Robinson, Nianzhi Jiao, Farooq Azam

Processing of DOC, interactions between MCP and BP, perturbations and links to humanity and large scale C cycling


Synthesis - Chairs: Carol Robinson, Nianzhi Jiao

Workshop 2 objectives and special issue

10:30-11:00 Coffee break
11:00-12:30 Synthesis continued
12:30-13:30 Lunch

Final plenary session

Summary reports from Workshops 1, 2 and 3 and plenary discussion sessions

15:00 Closing comments, end of meeting