Phytoplankton ecophysiology

Exploring the dynamic interactions of phytoplankton with their environment
Marine phytoplankton are an evolutionarily and metabolically diverse group of organisms that play vital roles in regulating global ocean processes. Despite their significant ecological importance, basic aspects of phytoplankton biology, physiology and genetics remain unexplored. A key motivation of my work is elucidating the fundamental molecular mechanisms that control how phytoplankton interact with their environment and other planktonic microbes in the ocean, how these interactions evolve, and the metabolic processes that govern them.

Vitamins are well characterised as essential nutritional components of the human and animal diet. However, accumulating evidence suggests that these organic micronutrients are important regulators of natural phytoplankton assemblages. A major focus of my work has been elucidating the molecular basis of phytoplankton vitamin dependencies, and their role in shaping biotic interactions between marine microbes. Using in silico genome mining coupled with physiological approaches I identified factors dictating the requirement for the cobalamin (vitamin B12) by eukaryotic algae (Helliwell et al, Molecular Biology and Evolution, 2011). Moreover, by applying an experimental evolution approach I demonstrated vitamin dependencies can arise rapidly in algal populations (Helliwell et al., ISME Journal., 2014). This led us to propose a novel model for the evolution of metabolic dependencies in microorganisms arising as a result of microbial interactions (Kazamia, Helliwell & Smith. Ecology Letters. 2016). More recently we discovered complex cycling of vitamin B12 between two major phytoplankton classes: the cyanobacteria and eukaryotic algae, driving competitive dynamics between these organisms (Helliwell et al., Current Biology. 2016).

The role of vitamins in regulating phytoplankton communities, is a rapidly expanding topic in biological oceanography and our work has contributed significantly to advancing our understanding of these important micronutrients in shaping marine microbial communities.

Katherine Helliwell

NERC Independent Research Fellow

Katherine Helliwell is a molecular microbiologist focussed primarily on the fundamental biology of photosynthetic marine microbes, which critically underpin marine ecosystems. She pursued a PhD and postdoc in the Department of Plant Sciences, University of Cambridge. During this time she dissected the role of organic micronutrients (vitamins) in governing interactions between phytoplankton and bacteria, and brought significant advances to our understanding in vitamin metabolism in microbes. Following her time in Cambridge, Katherine joined the MBA as a senior postdoctoral researcher working on phytoplankton signalling mechanisms. In summer 2018, Katherine was awarded a NERC Independent Research Fellowship and holds a joint fellowship between the MBA and the University of Exeter. Moving forward as a new lab, Katherine intends to couple her expertise in studying interactions between marine microbes, and phytoplankton signalling mechanisms, to better understand how marine microbes sense and respond to biotic cues.

Dominic Absolon

PhD Candidate (Cambridge Earth System Sciences NERC DTP, in partner with the MBA)

Department of Plant Sciences

University of Cambridge

Downing Street

Cambridge CB2 3EA


Staff List

Katherine Helliwell
NERC Independent Research Fellow, Joint University of Exeter and MBA Research Fellow

NERC Independent Research Fellow

Email: Telephone Number:
+44(0)1752 968639
Laura Branscombe
PhD Student

Laura graduated from Plymouth University in 2016 with a 1st in BSc in Marine Biology. After graduation she completed a master’s course in Oldenburg, Germany.

Email: Telephone Number:
+44 (0)1752 968087


Helliwell K. E., Kleiner F., Hardstaff H., Chrachri A., Salmon D., Smirnoff N., Wheeler G. L, and Brownlee C. (2021). Spatiotemporal patterns of intracellular Ca2+ signalling govern hypo-osmotic stress resilience in marine diatoms. New Phytologist, In press,

Helliwell K. E.+ , Harrison E., Christie-Oleza J., Downe J., Rees A., Al-Moosawi L, Brownlee C., Wheeler G. (2021) A novel Ca2+ signalling pathway co-ordinates environmental phosphorus sensing and nitrogen metabolism in marine diatoms. Current Biology, 31: 1-12, (+Corresponding author)

Helliwell K. E., Chrachri A., Koester J., Wharam S., Taylor A., Wheeler G., and Brownlee C. (2020) A novel single-domain Na+-selective voltage-gated channel in photosynthetic eukaryotes. Plant Physiology, 184 (4) 1674-1683.

Bunbury F., Helliwell K. E., Mehrshahi P., Davey M. P., Salmon D., Smirnoff N., Smith A. G. (2020) Physiological and molecular responses of a newly evolved auxotroph of Chlamydomonas to B12 deprivation. Plant Physiology, 183(1):167-178.

Leebens-Mack et al, inc. Helliwell K. E. (2019) One thousand plant transcriptomes and the phylogenomics of green plants. Nature. 574(7780):679-685

Helliwell K. E., Chrachri A., Koester J., Wharam S., Verret, F., Taylor A., Wheeler G., and Brownlee C. (2019). Alternative mechanisms for fast Na+/Ca2+ signalling in eukaryotes via a novel class of single-domain voltage-gated channels. Current Biology. 29(9) 1502-1511.

Cooper M.C., Kazamia E., Helliwell K. E.*, Kudahl U. J., Wheeler G. L., Smith A.G. (2018) Complex cross-exchange of B-vitamins underpins a mutualistic interaction between Ostreococcus tauri and Dinoroseobacter shibae. The ISME Journal.13(2):334-345 (*joint first authorship)

Wheeler G., Helliwell K. E., and Brownlee C. (2018) Diversity of calcium signalling toolkits in algae. Perspectives in Phycology. DOI: 10.1127/pip/2018/0082

Helliwell K. E., Pandhal J., Cooper M, Longworth J., Kudahl U., Russo D., Tomsett E., Bunbury F., Salmon D., Smirnoff N., Wright P., and Smith A. G., (2017). Quantitative proteomics of a B12‐dependent alga grown in coculture with bacteria reveals metabolic tradeoffs required for mutualism. New Phytologist. 217(2): 599-612 

Helliwell K. E. (2017). The roles of B vitamins in phytoplankton nutrition: new perspectives and prospects. New Phytologist. 216(1): 62-68 (*Corresponding author).

Brawley S. H., Blouin N. A., Ficko-Blean E., Wheeler G. L., Lohr M., Goodson H., Jenkins J., Blaby-Haas C. E., Helliwell K. E., et al., (2017). Insights into the red algae and eukaryotic evolution from the genome of Porphyra umbilicalis (Bangiophyceae, Rhodophyta). PNAS. 14 (31) E6361-E6370

Helliwell K. E., Lawrence A., Holzer A., Kudahl U. J., Sasso S., Krautler B., Scanlan D., Warren M., Smith A. G. (2016). Cyanobacteria and eukaryotic algae use different chemical variants of vitamin B12. Current Biology. 26(8): 999-1008 (*Corresponding author).

Kazamia E., Helliwell K. E., Smith A. G. (2016). How mutualisms arise in phytoplankton communities: building eco-evolutionary principles for aquatic microbes. Ecology Letters. 19(7):810-822. 

Nguyen G., Scaife M. A., Helliwell K. E., Smith A. G. (2016). Algal riboswitches: rare or yet to be discovered? Journal of Phycology. 52(3):320-328

Wells M., Potin P., Craigie J., Raven J., Merchant S., Helliwell K. E., Smith A., Brawley S. (2016) Algal products as nutritional and functional foods: The status of our understanding. Journal of Applied Phycology. 29(2):949-982

Helliwell K. E.*, Collins S., Kazamia E., Purton S., Wheeler G. L., Smith A. G. (2015). Fundamental shift in vitamin B12 eco-physiology of a model alga demonstrated by experimental evolution. The ISME Journal. 9(6):1446-55 (*Corresponding author).

Scaife M. A., Nguyen G. T., Rico J., Lambert D., Helliwell K. E., Smith A. G. (2015). Establishing Chlamydomonas as an industrial biotechnology host. The Plant Journal. 82(3):532-546.

Helliwell K. E., Scaife M. A., Sasso S., Ulian Araujo A., Purton S., Smith A. G. (2014). Unraveling vitamin B12-responsive gene regulation in algae. Plant Physiology. 165(1):388–397

Helliwell K. E.*, Wheeler G. L, Smith A. G. (2013). Widespread decay of vitamin-related pathways: coincidence or consequence? Trends in Genetics. 29(8):469–78 (*Corresponding author). See piece in NY Times exploring this work: 

Helliwell K. E., Wheeler G. L., Leptos K., Goldstein R., Smith A. G. (2011). Insights into the evolution of vitamin B12 auxotrophy from sequenced algal genomes. Molecular Biology and Evolution. 28(10):2921–33.

Kazamia E., Helliwell K. E., Smith A. G. (2010). Vitamin B12- Keeping a Clear Head. The Biochemist: 32(6).

Science Communication and outreach

Article in NERC Planet Earth

Helliwell K. E., Vitamins in the Sea: the role of vitamins in shaping phytoplankton evolution and ecology. The Marine Biologist (2018).

New York Times: Vitamins' Old, Old Edge

Cambridge University Meet the Algae video

Kazamia E., Helliwell K.E. and Smith A.G. Keeping a clear head with vitamin B12. (2010). The Biochemist 32(6): 20 -24.

The Marine Biological Association of the United Kingdom,

The Laboratory,

Citadel Hill,