The marine haptophyte alga Phaeocystis can form massive blooms that are commonly observed as frothy foam on our seashores (Verity et al. 2007). Thereby they produce a large biomass and act as a major contributor to primary production particularly in coastal regions like the English Channel (Widdicombe et al. 2010; Keys et al. 2017). Phaeocystis exist primarily as single cells, but under certain conditions produces large gelatinous colonies due to secretion of extracellular polysaccharides. Colonies can form large aggregates that sink to the deeper ocean redirecting material flow away from higher trophic levels (Verity et al. 2007, Smith and Trimborn 2024). Phaeocystis is regarded as harmful alga, because high local abundance can result in deoxygenation which negatively affects fish. Mass occurrence has been linked with phosphate availability and at Station L4 of the Western Channel Observatory the Phaeocystis bloom coincides with changes in phosphate concentration (Widdicombe et al. 2010, https://www.westernchannelobservatory.org.uk/l4_nutrients.php).
Phosphate is an essential nutrient for phytoplankton growth hence many organisms developed an adaptation mechanism to its scarcity. Under limiting phosphate concentrations, cells replace phospholipids with phosphate-free lipids to reduce their cellular demand (Van Mooy et al., 2009). While the lipid composition of Phaeocystis cells has been studied (e.g. Maat et al. 2014), how the individual life cycle stages respond to phosphate limitation and whether their lipid profiles differ has yet to be resolved.
This project will use laboratory culture and field-based community analysis during a Phaeocystis bloom to observe how solitary and colony forming Phaeocystis life cycle stages respond to varying phosphate availability.
Firstly, this project aims to determine lipid marker molecules from unialgal culture to trace during a Phaeocystis dominated bloom and observe differences between single flagellated and colony-forming cells. Therefore, the phototrophic microbial community will be traced using 18S rRNA metabarcoding to correlate lipid profiles with community shifts.
Second, it aims to observed lipid remodelling due to phosphate variability in microcosm enrichments and the natural Phaeocystis dominated community to trace back patterns observed in the lab to natural field data. By isolating Phaeocystis we will further be able to analyse differences between regional field and lab strains.
This project does not offer a CASE studentship
Each host has a slightly different application process.
Find out how to apply for this studentship.
All applications must include the CENTA application form.
Choose your application route
This project will combine laboratory with field-based analysis. Phaeocystis sp. will be cultivated and analysed in the lab under normal and limiting phosphate condition. Both cell types, solitary and colonial cells shall be studied. Field sampling will consist of microcosm enrichments and weekly analyses during spring bloom development, bloom peak and decline with attempts to isolate Phaeocystis from Plymouth sound water.
Samples will be processed for lipid analysis using in-house liquid chromatography-mass spectrometry (LC-MS) instrumentation. Microbial community analyses will be carried out using 18S rRNA gene eukaryotic metabarcoding. Additionally, a lipid biosynthesis-based gene marker shall be developed using phylogenetic analysis. Nutrient data, imaging data from an Imaging FlowCytobot deployed in the field and FlowCam data will be available from Plymouth Marine Laboratory (PML).
DRs will be awarded CENTA Training Credits (CTCs) for participation in CENTA-provided and ‘free choice’ external training. One CTC can be earned per 3 hours training, and DRs must accrue 100 CTCs across the three and a half years of their PhD.
The student will receive training in a range of techniques in the supervisor’s and co-supervisors’ labs at the University of Warwick and the Marine Biological Association (MBA). This will include microbial techniques from cultivation to cell quantification (flow cytometry), lipid extraction and analysis via LC-MS, and field sampling methods, particularly filtration. For microbial community analysis the student will learn sample preparation for amplicon sequencing and usage of bioinformatics pipelines such as Qiime2 will be required. Participation in Sea Survival training and sampling trips on the research vessel Plymouth Quest of the Plymouth Marine Laboratory (PML) are essential.
The supervisory team is composed of researcher with complimentary expertise and varying degrees of experience. Dr Mausz is a new group leader with a track record in microalgae research and lipidomics. Dr Puxty is a biogeochemist focusing on cyanophage research and bioinformatics. As experienced molecular cell biologist stationed at the MBA Dr Wheeler will additionally provide access to natural samples, lab space to conduct field-related work and the Plymouth Culture Collection of Marine Algae. Plankton ecologist Dr Widdicombe will advise on sampling times and strategies and provide access to Station L4 field sampling and data at PML.
Year 1: Lipidomics of Phaeocystis lab culture and development of a potential lipid-based community marker. Conduction of a microcosm enrichment experiment during the spring bloom.
Year 2: Processing and analysis of samples from enrichment experiment and conduction of community sampling around a Phaeocystis spring bloom.
Year 3: Study of a Phaeocystis isolate and community sampling processing and analysis.
Key M, Tilstone G, Findlay HS, Widdicombe CE, Lawson T (2017) Effects of elevated CO2 on phytoplankton community biomass and species composition during a spring Phaeocystis spp. bloom in the English Channel. Harmful Algae 67, 92-106.
Maat DS, Bale NJ, Hopmans EC, Baudoux A-C, Sinninghe Damsté JS, Schouten S, Brussaard CPD (2014) Acquisition of intact polar lipids from the prymnesiophytes Phaeocystis globosa by its lytic virus PgV-07T. Biogeosci 11, 185-194. https://doi.org/10.5194/bg-11-185-2014
Van Mooy BAS, Fredricks HF, Pedler BE, Dyhrman ST, Karl DM, Koblížek M, Lomas MW, Mincer TJ, Moore LR, Moutin T, Rappé MS, Webb EA (2009) Phytoplankton in the ocean use non-phosphorus lipids in response to phosphorus scarcity. Nature 458, 69-72.
Verity PG, Brussaard CP, Nejstgaard JC, van Leeuwe MA, Lancelot C, Medlin LK (2007) Current understanding of Phaeocystis ecology and biogeochemistry, and perspectives for future research. Biogeochem 83, 311-330. doi: 10.1007/978-1-4020-6214-8_21
Widdicombe CE, Eloire D., Harbour D, Harris RP, Somerfield PJ (2010) Long-term phytoplankton community dynamics in the Western English Channel. J Plankton Res 32, 643–655. https://doi.org/10.1093/plankt/fbp127
Smith WO, Trimborn S (2024) Phaeocystis: A global enigma. Annu Rev Mar Sci 16, 417-441. https://doi.org/10.1146/annurev-marine-022223-025031
Applicants should hold a BSc and/or MSc degree or equivalent in a relevant subject. Informal enquiries can be directed to Dr Michaela Mausz ([email protected]).
To apply to this project:
Applications must be submitted by 23:59 GMT on Wednesday 6th January 2027.