General context Five Belgian Institutions (the Royal Belgian Institute of Natural Sciences: Department of Invertebrates (RBINSc); the Royal Museum for Central Africa, Section of Mineralogy, Petrography and Geochemistry (MRAC); UniversitÈ Libre de Bruxelles, Laboratoire de Biologie Marine (ULB); Vrije Universiteit Brussel, Laboratory of analytical Chemistry and Laboratory of Isotope Geochemistry (VUB); University of Antwerp, Ecophysiology, Biochemistry and Toxicology Unit, Department of Biology (UA) have set up a project to validate the use of CALcareous MARine Skeletons as recorders of global climate changes. Potential recorders have been selected among three taxa: sclerosponges, bivalves, and echinoderms, for their contrasted characteristics: lifetime, growth rate, and mineralisation features. Areas of interest spread from the North East Atlantic Ocean to the Caribbean. Objectives The potential as environmental recorders of sclerosponges, bivalves, and echinoderms is well known, and the originality of CALMARS rather resides in three new perspectives. the comparative analysis of contrasted taxa will sustain the validity of the recorded global changes; laser ablation technology will ensure day to seasonal resolution depending of the taxon used; focus will go to a better understanding of the pathways of proxy incorporation and on the relative controls by environmental and physiological conditions, emphasising on reconstruction of sea surface temperature (SST), salinity, phytoplankton biomass and productivity, and trace metal content. Methodology CALMARS approach is based on a combination of field and laboratory work. Field work consists in regular samplings of each group at a few selected sites in both tropical and temperate settings (North Sea & Scheldt, Norway, Jamaica and Kenya) where long-term monitoring of environmental conditions is carried out to follow up the recording of seasonal variations in the skeleton. Single samplings along environmental gradients are also performed in order to assess the recording of latitudinal variations. Specimens preserved in museums will help to extend data in time and localities. Proxies studied are Mg, Sr, Ba, Cd, Mn, U, B, Pb, Zn and O13Ccarb, O18Ocarb, using laser ablation ICP-MS in order to gain a high time resolution. Effects of environmental parameters are tested for each group under experimental conditions (in situ with incubation chambers or in aquarium). Impact of ambient substrate concentrations and physico-chemical conditions are also studied in controlled in-vitro experiments, during which incorporation of proxy are followed after radioactive and stable isotope spiking to ascertain results obtained along naturally occurring gradients. Link with International Programmes Paleo-oceanographic studies of climate change to modern-day analyses of pollution impacts. Expected results and/or products CALMARS aims at improving and extending the records of global change in the oceanic domain with a peculiar interest for the climate databases. Through a network of biologists and geochemists of complementary experience, CALMARS intends to: better validate the existing proxies by a thorough experimental investigation of the physiological and environmental factors that interplay to control the proxy incorporation within the various existing mineralogical types of biogenic carbonates; refine the existing records by improving the recently developed analytical tools and generating very-high resolution records of the validated proxies; greatly enlarge the application scales of these proxies by a direct comparison of different biological taxa under contrasted tropical and temperate settings from the North Atlantic ocean. From this, CALMARS expects to generate robust high-resolution time series of several tracers which are of prime importance to better simulate the carbon cycle and will therefore be used by other research networks to understand present day global change and predict future changes; develop algorithms for climatic and environmental change from proxy records. Development of educational aspects from this research is planned by creating and regularly updating a web-site, describing the main lines of the research. A scientific film and/or a didactic CD-ROM produced by the pedagogic staffs from the two involved federal scientific institutions (IRSNB and MRAC) are also planned.