Zoe G. Cardon

Senior Scientist

Tel: 508-289-7473 | Fax: 508-457-1548
E-mail: zcardon@mbl.edu

MBL Greenhouse Research Facility

Ph.D., Stanford University, 1994
B.S., Biology; B.A., Spanish, Utah State University, 1988

Full CV

Micro-Eco Discussion Group Schedule

Research Statement

We have several long-term projects active in the lab, each linking plants, soils, and microbes in a unique way. Overall, we are driven to understand how biogeochemical cycles have dramatically affected, and been dramatically affected by, evolutionary changes in the anatomy and physiology of organisms on Earth, and by the ecological interplay of those organisms above- and below-ground in complex mutualisms, symbioses and food webs.

Current Projects

Collaborative Research: MSB: The Role of Sulfur Oxidizing Bacteria in Salt Marsh C and N Cycling
PIs (MBL): Zoe Cardon and Anne Giblin, Ecosystems Center, MBL
PI (WHOI): Stefan Sievert, Biology
Salt marshes are extraordinarily productive ecosystems found in estuaries worldwide, but many receive high nitrate input from land, degrading water quality, and leading to harmful algal blooms and low oxygen zones harmful to fish. We are investigating environmental and microbial controls over the fate of nitrate in salt marshes, in lab and field experiments at Plum Island Ecosystems LTER and the MBL Research Greenhouse. We are focusing on sulfur-oxidizing bacteria -- chemosynthetic microbes that use energy trapped in sulfur compounds in sediment to grow. Many of these bacteria can use nitrate as a terminal electron acceptor, transforming it either into dinitrogen gas (N2) via denitrification, or ammonium (NH4+) via DNRA, thus affecting the fate of pollutant nitrate in the marsh.
We are (1)identifying sulfur-oxidizers present in sediment densely populated with the salt marsh grass, Spartina alterniflora, and examining their gene expression linked to sulfur and nitrate processing under shifting environmental conditions; and (2) combining this molecular information with measurements of rates and characteristics of biogeochemical reactions occurring in the sediment.

Hydraulic redistribution of water through plant roots – implications for carbon cycling and energy flux at multiple scales
PI: Zoe Cardon, Ecosystems Center, Ecosystems Center, MBL
Co-PIs: Rebecca Neumann, University of Washington
Guiling Wang & Daniel Gage, University of Connecticut
This project aims to advance quantitative and predictive understanding of “hydraulic redistribution” (HR) in seasonally dry ecosystems. During HR, soil water moves upward, downward, or horizontally from moist to dry soil through plant roots, which serve as conduits connecting soil volumes. Using a linked suite of empirical experiments, small-scale mechanistic modeling (using the reactive transport model Min3P), and terrestrial ecosystem and earth system modeling (using CLM4.5 modified with a version of Ryel et al.’s 2002 HR model), we are exploring HR’s impact on terrestrial carbon, nitrogen, water, and energy cycles. Large scale modeling draws from greenhouse and field data (from 8 Ameriflux sites), and incorporates information from mechanistic modeling in order to improve the representation of HR in earth system models and to quantify the effects of HR on terrestrial ecosystems in past and future regional climates.

Photoprotection in Diverse, Desiccation-Tolerant, Desert Green Algae and Their Close Aquatic Relatives
Lead PI: Zoe Cardon, Ecosystems Center, MBL
Collaborator: Doug Bruce, Brock University, Ontario, Canada
A key step in the evolution of diverse life on Earth was the expansion of organisms’ territories from living in water to surviving on land. Green plants are by far the largest group of advanced photosynthetic organisms to have become established and diversified on land. Flowering plants, evergreen conifers, mosses, and ferns have long been studied for clues to the traits important for terrestrial survival, however, they are all descended from a single green algal ancestor that successfully invaded land. Traits they share may be essential for surviving the rigors of terrestrial life, or they might simply be traits inherited from the common ancestor, as evolutionary baggage. To tease apart these two possibilities, other green, photosynthetic, terrestrial organisms must be studied that are not descended from that common green algal ancestor. Such a suite of organisms is found among diverse, free-living, microscopic green algae inhabiting microbiotic crusts of the desert Southwestern U.S. The objective of this research is to determine the process(es) underlying a very powerful mechanism protecting the photosynthetic apparatus of green algae isolated from microbiotic crusts, during desiccation and rehydration.Understanding desiccation tolerance mechanisms is important because these desert green algae share many characteristics with larger agriculturally and ecologically important green plants, and also with the green algae increasingly used for biofuel production.

"Integration of Pore-Scale Simulations and Multi-Omics Data to Develop Insights into Functional Heterogeneity in Microbial Communities"
Lead PI: Zoe Cardon, Ecosystems Center, MBL
Co-Is: Joe Vallino and Gretta Serres, MBL; Tim Scheibe, EMSL and PNNL.
This project aims to develop a computational framework, on the CASCADE supercomputer at PNNL, that embeds very diverse microbial community structure and function within high resolution 3D environmental structure at pore (tens of micrometer) scales. The work emerges from fundamental questions in basic and applied microbial ecology:
• How does 3D microenvironmental structure affect, and how is it affected by, microbial community structural diversity and expression of microbial function?
• How does environmental microheterogeneity affect resulting process rates measured at larger scales, and our ability to predict them, e.g. in bioremediation, ecosystem function, food, or fuel production?
This approach recognizes biotic information in “omics” datasets as a signal resulting from structured interaction between the microbiotic and the abiotic at microscales. Recognizing this interaction will support greater understanding of how microbial functional and community diversity in natural and man-made ecosystems persist.

A novel low-waste, low-maintenance system for microbial generation of methane from algal biomass
Co-PIs: Zoe Cardon and Joe Vallino, Ecosystems Center, MBL
Using a suite of algal species, and a variety of mixed decomposer and methanogenic microbial communities, this project aims to maximize methane production from algal biomass, with minimal maintenance requirements and waste production by the system.

Recent publications

Thomas F, Giblin AE, Cardon ZG and Sievert SM. 2014. Rhizosphere heterogeneity shapes abundance and activity of sulfur-oxidizing bacteria in vegetated salt marsh sediments. Frontiers in Microbiology 5:309. doi: 10.3389/fmicb.2014.00309

Neumann R, Cardon ZG, Teshera-Levye J, Rockwell F, Zwieniecki M, Holbrook NM. 2014. Modeled hydraulic redistribution by sunflower (Helianthus annuus L.) matches observed data only after including nighttime transpiration. Plant Cell and Environment 37:899-910,doi: 10.1111/pce.12206.

Cardon ZG, Stark JM, Herron PM, Rasmussen JA. 2013. Sagebrush carrying out hydraulic lift enhances surface soil nitrogen cycling and nitrogen uptake into inflorescences. Proceedings of the National Academy of Sciences, Nov. 4 online first: www.pnas.org/cgi/doi/10.1073/pnas.1311314110.

Herron PM, Gage DJ, Arango Pinedo C, Haider ZK, Cardon ZG. 2013. Better to light a candle than curse the darkness: illuminating spatial localization and temporal dynamics of rapid microbial growth in the rhizosphere. Frontiers in Plant Science 4:323. doi:10.3389/fpls.2013.00323

Lunch, CK, LaFountain, AM, Thomas, S, Frank, HA, Lewis, LA, Cardon, ZG. 2013. The xanthophyll cycle and NPQ in diverse desert and aquatic green algae. Photosynthesis Research, 115:139–151.

Neumann, R.B. and Z.G. Cardon. 2012. The magnitude of hydraulic redistribution by plant roots: a review and synthesis of empirical and modeling studies. New Phytologist 194:337-352.


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