Diatoms are unicellular algae that are characterised by the possession of highly structured siliceous walls. They are probably the most successful group of algae, being found throughout the world, in both marine and freshwater systems, as well as subaerial and terrestrial habitats. It has been estimated that they contribute at least 20-25% of primary production in the world.
My work can be summarized under four project headings:
Developing valve of Gomphonema truncatum showing raphe slits and lateral ribs. Scale bar = 10 microns. © EJC (NHM)
Diatom cells have a unique wall structure in which the two halves of the siliceous ‘box’ enclosing the cell are formed at different times. Each cell has an older and a younger half wall (valve), but both are formed under the control of the genotype and morphogenesis follows a particular order in each taxon. However, if genotypic expression varies with environment, the resulting phenotypes will differ according to conditions at the time of formation. Thus, it is possible that if the two valves of a single cell developed under different external conditions they will differ morphologically. Understanding how particular valve features are formed, and under what conditions they can be transformed is important for their interpretation for systematic analyses.
I am particularly interested in the generic relationships of naviculoid diatoms and how well the current diatom classification reflects those relationships. Recent work has included studies of the relationship between the monoraphid genus Achnanthes and the Mastogloiales, as well as an investigation of the marine genus Proschkinia.
Diatoms have traditionally been identified on their wall characters after cells have been ‘cleaned’, i.e. the organic components have been removed by oxidation. However, this means that assemblages analysed from such material may include cells that were not alive at the time of sampling, or were washed-in from other habitats. This may skew ecological interpretation based on the assemblage.
However, it is possible to identify many diatoms from fresh, living material using cell contents, particularly chloroplast arrangement.
I am currently working on a revision of my book “Identification of freshwater diatoms from live material” and will be incorporating a CD of photomicrographs in the second edition.
Because their cell walls are well-preserved in many sediments, diatoms have been used extensively as palaeo-ecological indicators of pH, trophic status, salinity, etc. They are also widely used as bioindicators of contemporary conditions (especially under the Water Framework Directive). This work has relied on correlations between assemblage composition and measured field conditions, rather than empirical evidence of species responses to particular environmental variables.
I have used an experimental approach to determine whether inferred relationships based on field data are supported by growth responses in the laboratory.
Dr Jonathan Tyler - from 1st March 2009 (NERC Research Fellow)
Former post-doc collaborators
Rosa Trobajo - Experimental studies of morphological and physiological variation in Nitzschia spp: improving taxon delimitation and determining ecological tolerances for water quality assessment using diatoms.
Ingrid Jüttner - Diatoms as indicators of environmental change – Himalayan streams as model ecosystems for investigations of natural and anthropogenic change.
Dave Emson (UCL) - The impact of Lemna on pond ecosystems: an ecological and palaeoecological study using diatoms as a proxy.
Katie Bentley (UCL) - Adaptive behaviour through morphogenesis: inspiration from diatoms.
Dawn Rose (Plymouth) - Ecophysiological and taxonomic discrimination of widely distributed benthic diatoms used as indicators of pollution.
2009-2012 Calibrating the fractionation of stable oxygen and silicon isotopes in diatom silica through laboratory culture experiments
NERC fellowship for Dr Jonathan Tyler
2006 Cingulum structure, function and ontogeny in Mastogloialean diatoms.
Systematics Association small grant.
2004-2006 Experimental studies of morphological and physiological variation in Nitzschia spp: improving taxon delimitation and determining ecological tolerances for water quality assessment using diatoms.
European Commission, Marie Curie Research Fellowship (for Rosa Trobajo).
2004-2007 The transition metal isotope systems as tracers of nutrient cycling and usage in the present and past oceans.
NERC. (Principal investigator D. Vance, University of Bristol.)
2003-2004 Isotopic studies of the biogeochemistry of the transition metals in seawater
Leverhulme Trust. (Principal investigator D. Vance, University of Bristol.)
2000-2002 Diatoms as indicators of environmental change – Himalayan streams as model ecosystems for investigations of natural and anthropogenic change.
European Commission, Marie Curie Research Fellowship (for Ingrid Jüttner).
2000 Interactions between nanoflagellates and diatoms in the marine plankton
Museum Research Fund, The Natural History Museum (with Dr G. Novarino, Zoology & Dr J. Young, Palaeontology).
1994-1996 Diatoms, Salt lakes and climate change: Inter-regional datasets and transfer functions for global application
NERC. (with University College London)
1990-1993 Flora of the Marine Diatoms of the British Isles.
NERC grant with University of Bristol and Royal Botanic Garden, Edinburgh.
National Galleries and Museums of Wales (Cardiff)
Royal Botanic Garden, Edinburgh
Unitat d’Ecosistemes Aquàtics (EUA-IRTA), St Carles de la Ràpita, Spain
University of Cardiff
University College London
University of Plymouth
2001-2004 Member of Council, Systematics Association
1997-1999 Member of Council, Systematics Association
1995-1997 Member of Council, International Phycological Society
1993-1995 Member of Council, Systematics Association
Member of organising committee, 5th, 7th & 8th International Phycological Congresses
Member of organising committee, 2nd & 3rd European Phycological Congresses
Member of local organising committee, British Phycological Society Meetings (1998, 2002, 2009)
NERC Advanced Research Fellow, 1990-1992
Max-Planck-Gesellschaft Research Fellow, 1982-1985
Royal Society European Exchange Research Science Programme Fellow, 1980-1981
Claridge Druce Junior Research Fellow in Plant Taxonomy, 1977-1980
British Phycological Society
International Phycological Society
International Society for Diatom Research
Linnean Society of London
Phycological Society of America
European Journal of Phycology
2003 - Reading Microscopical Club,
2002 - Quekett Microscopical Society, M.C. Cooke lecture, The Natural History Museum, London.
Sorting out the rag-bag – live material, SEM data and the systematics of naviculoid diatoms.
1996 - National Science Week, The Natural History Museum, London.
From microscopical curiosities to environmental indicators - aspects of diatom research over the last 150 years.
1991 - Sorby Natural History Club, Sheffield.
Diatoms: size, shape and species.
1991 - Postal Microscopical Society 11th National Meeting & Exhibition, Sheffield.
There's more to diatoms than dots.
1990 - Sorby Natural History Club, Sheffield.
Shaping up to the environment - adaptation of the algae to their habitats.
1979 - Natural History Society, Oxford.
Pillboxes of the plant kingdom.
Foundation for Science & Technology visit, NHM, Live diatom demonstration. 2003
DC2 presentations (6) – Is it plant or animal? An introduction to freshwater diatoms. 2002, 2003
Backyard biodiversity day, Chelsea Physic Garden, June 2001, 2002
Interview on diatoms for Focus – January 2000.
“Meet the scientist”, Voyages of Discovery, NHM – November 1999.
Filming and voice-over for Channel 4 Science Education Series, “Seeing with electrons” – April 1998.
“Women and science”. 2 informal talks to 13-14 year old girls at Ricards Lodge High School, Wimbledon, London – February 1997.
Interview for Sunday Telegraph, 1995.
NHM stand at British Association for the Advancement of Science, Newcastle, 1995.
Interview for BBC Today programme during BAAS meeting, 1995.
“Meet the Scientist”, National Science Week, 1993.
Annually 1996-present Kindrogan Field Centre One week course on freshwater algae
2008 UCL EA training workshops
2002 Quekett Microscopical Club 1day workshop on marine diatoms
2000 Kirkwall, Orkney Weekend course on freshwater algae
1993 NHM and Durham University Introduction to freshwater diatom
1994 NHM and Durham University Introduction to freshwater
1995 Advanced Diatom Analysis course UCL Diatom taxonomy
1994 NRA Anglian Region 1 day diatom workshop
Evening lectures and practicals within adult education courses at NHM (1992, 1993);
1 day workshop on freshwater diatoms for Quekett Microscopical Club (1999)
Marine diatoms within an ECSA Workshop, Dove Marine Laboratory, Cullercoats (1991)
1 day workshop on freshwater diatoms for Extra-mural studies, University of Sheffield (1991).
Invited specialist, 5th Workshop of the International Association of Phytoplankton Taxonomy and Ecology, Stirling, (1984)