The Network 
CODENET is a research network of eight European geological and marine biological teams, funded by the EC Training and Mobility of Researchers programme to carry out an integrated multidisciplinary study of six coccolithophorid species. The TMR funding runs from January 1998 to September 2001, it provides support for post doctoral researchers in most groups plus network activities and a contribution toward research costs. 

NHM - The Natural History Museum, London 
Key Participants: Jeremy R. Young, Markus Geisen, Franco Novarino, Paul Bown (UCL) 
Main research areas: Microevolution and physiology of three of the key species. Phylogeny and biomineralisation across the group. 
ETHZ - Eidgenössische Technische Hochschule, Zürich - Geological Institute 
Key Participants: Prof Hans Thierstein, Patrick Quinn, Sabrina Renaud (now at U. Lyon), Christine Klaas (now at Chicago University), Jörg Bollman 
Main research areas: Microevolution, ecology and palaeoecology of Calcidiscus leptoporus and Gephyrocapsa, development of online species database (EMIDAS)

VUA - Vrije Universiteit Amsterdam - Earth Sciences Faculty 
Key Participants: Prof. Jan van Hinte, Gerald Ganssen, Patrizia Ziveri, Annelies Kleijne, Peter Westbroek (Leiden) 
Main research areas: Sediment trap studies, coccolith stable isotopes, and study of the biogeography of Helicosphaera carteri, Syracosphaera pulchra and Umbilicosphaera sibogae

U. Caen - Universite de Caen Basse-Normandie - Marine Biology and Biotechnology Lab. 
Key Participants: Prof. Chantal Billard, Prof. Jacqueline Fresnel, Ian Probert, Aude Houdan. 
Main research areas: Culture isolation and maintenance, life-cycle studies and TEM fine structural study. 

AWI - Alfred-Wegener-Institute for Polar & Marine Research, Bremerhaven 
Key Participants: Linda Medlin, Alberto Saez, Volker Huss (Erlangen) 
Main research areas: Molecular genetics - including evaluation of large scale phylogeny, intraspecific genetic differentation and special study of the plastid genome size. 

CSIC - Consejo Superior de Investigaciones Cientificias - Instituto de Ciencias del Mar 
Key Participants: Prof. Marta Estrada, Kees van Lening, Joan Grimalt (CID), Mikel Latasa, Lluisa Cros, Ramon Margalef. 
Main research areas: Cruise-based study of biogeography and ecology of the species. Biochemical studies of their photosynthetic pigments. 

MNHN-UL - Museu Nacional de Historia Natural da Universidade de Lisboa 
Key Participants: Mario Cachão, Anabela Olivera (UCTRA), Maria Teresa Moita, Maria da Graca Vilarinho (IPIMAR), Alexandra Duarte Silva. 
Main research areas: biogeographic and ecological study focussed on the Portuguese shelf. Detailed study of intraspecific variation and microevolution in the species Coccolithus pelagicus

NIOZ - Nederlands Instituut voor Onderzoek der Zee 
Key Participants: Jaap Sinninghe Daamsté, Hanno Kinkel, Gerard Versteegh 
Main research areas: Lipid biochemistry and biogeochemistry of the species. Identification of holococcolith-heterococcolith life-cycle pairings  

OTHER PARTICIPANTS: In addition to the core funded teams several other groups are actively collaborating in the project in various ways including particularly:

U. Bremen - Universität Bremen
Key Participants: Karl-Heinz Baumann, Claudia Sprengel, Babette Boeckel
Main research areas: Morphometric study of intraspecific variaton in the CODENET species in plankton, sedment trap and geological samples;

U. Oviedo - University of Oviedo
Key Participant: Heather Stoll
Main research area: Study of Sr/Ca ratios in coccolith calcite, development and testing of this novel palaeoproxy

Other collaborators include teams in: Bristol University, Friedrich-Alexander-Universität Erlangen-Nürnberg, Ruhr-Universität Bochum, Università degli studi di Milano, Università degli studi di Firenze, University College London 

Research Strategy 
Coccolithophorids are one of the main open ocean primary producers, they play key roles in the global carbon, carbonate and sulphur cycles. Their coccoliths are the single most important component of deep-sea oozes and chalks and provide key floral, isotopic, and biomarker signals for interpreting global change in the geological record. Their exceptional fossil record makes them an outstanding biostratigraphic group and gives them unusual potential for testing evolutionary hypotheses. So they are being actively studied by a wide range of research groups. This convergence  of interests  formed the basis for the  Global Emiliania Modelling (GEM) initiative, including a previous MAST funded EC project EHUX. The research strategy of focusing different types of study on the single species Emiliania huxleyi, proved a very successful way of developing useful collaboration between a disparate group of specialists. The CODENET project develops this approach by taking a set of six carefully selected taxa. These will allow sets of case studies to be built up and provide a controlled sampling of the biodiversity of coccolithophorids. 
The CODENET project incorporates 15 different research tasks, or sub-projects, as indicated in the figure below. These basically fall into two main groups.

    To see high resolution versions of these figures click on them 

overview phylogeny

Culture based biological and biochemical studies 
Coccolithophorids can be maintained in culture thus allowing a range of laboratory based studies. Isolating  and maintaining cultures requires significant effort, so a key aspect of the CODENET strategy is to devote considerable resources to obtaining cultures and then to make them available directly to the participant teams. This maximises the value of the culture isolation and avoids duplication of effort. Culture based research tasks include life-cycle studies, molecular genetics, study of lipid biomarkers and pigment composition, study of coccolith carbonate stable isotope and trace element composition, ultrastructural studies of cytology and coccolith biomineralisation, physiological studies on the effect of variation in culture conditions on growth rates and coccolith morphology. 

Oceanographic and Geological Sample based studies 
Coccolithophorids are abundant in a wide range of types of samples, including phytoplankton samples collected during oceanographic cruises, sediment trap time series samples of material sinking through the water column, surface sediment samples of recent assemblages and geological samples providing a continuous record of evolutionary change. Each of these types of samples provides different types of information and is usually studied independently. Within the CODENET project we are including study of each sample type, allowing integration of results to address particular questions (see objectives below). In most cases common samples sets are being used by different research teams each studying particular taxa. 

The scale of  the CODENET project enables us to approach fundamental aspects of coccolithophorid biology and to address questions which cannot be effectively answered by single research studies. As outlined below and indicated in the diagram above  the project is designed to address a range of  objectives within three work areas: 

1. Evolutionary Biodiversity  
Taken together studies on the six taxa enable us to investigate diversity across the coccolithophorids and to determine its relationship to phylogeny. Our key objectives are to: 

  • Determine the major patterns of biodiversity in coccolithophorid life-cycles, biomarker composition, photosynthetic pigments, cytology and plastid genome. 
  • Re-evaluate the phylogeny of the coccolithophorids using separate and combined analyses of: molecular genetic (AWI), morphological (NHM) and biochemical (NIOZ, CSIC) data and compare this with the palaeontological record of coccolithophorid evolution (NHM, ETHZ). Calculate divergence times of groups and rates of evolution, including molecular clock calibrations (AWI, ETHZ). 
  • Reconstruct the sequence of major evolutionary steps in coccolithogenesis, lipid biochemistry, plastid evolution, and life cycle differentiation.

2. Microevolution and Species Level Variation  
Each of the six taxa will provide detailed case studies of evolution and species-level variation including complimentary studies of living and fossil material. Our key objectives are to: 

  • Evaluate which aspects of variation represent genotypic vs. ecophenotypic or ontogenetic variation.
  • Determine whether intra-specific variability in morphology, physiology and biochemistry are correlated, defining discrete sub-species.
  • Determine whether physiological adaptation occurs within local sub-populations independently of other genotypic characters.
  • Determine whether microevolution occurs by (sub-)species selection or effectively sympatric evolution within ocean-scale populations.

3. Coccolithophorid Ecology  
By building up detailed knowledge of the biology of key species and combining a range of types of population studies we aim to make a fundamental reassessment of our understanding of coccolithophorid ecology, in particular to: 

  • Determine whether coccolithophorids as a group occupy a distinctive ecological niche, and if so characterise it.
  • Determine which aspects of intra- or inter-specific assemblage variation are most valuable for palaeoecological calibrations and develop palaeoecological proxies.
  • Determine the extent to which coccolithophorid carbonate accumulation rate is affected by species composition and evolution.
  • Develop and calibrate coccolith-based geochemical palaeoproxies for palaeoceanographic research.


This page was written by Markus Geisen (, feedback welcome

More detailed information is available from the CODENET WWW Site