Objetivo Objectives: To establish a link between the marine carbon and sulfur cycles. Contents: Both cycles are relevant to climate change studies, carbon being the main contributor to the greenhouse effect, and sulfur as an important source of cloud condensation nuclei, thereby regulating cloud albedo. Greenhouse effect and cloud albedo are two opposing mechanisms. The former results in global warming, the latter in cooling of the earth's climate. Both cycles meet intimately in the ubiquitous marine phytoplankton taxon Phaeocystis sp.. This colony-forming alga is an important source of the volatile organic sulfur compound dimethyl sulfide (DMS), and its dense blooms can act as a carbon sink. A thorough inventory of the carbon and sulfur cycles will be made during two blooms of Phaeocystis in two different geographical areas: in northern Norwegian coastal waters and in the Southern Bight of the North Sea. These field campaigns will be preceded and followed by well defined laboratory experiments in order to study isolated processes relevant for the field situation. In many coastal areas a stereotype pattern of algal succession during the spring bloom is observed in which Phaeocystis outcompetes other algal species. Due to the time development of various processes influencing the wax and wane of a phytoplankton bloom, sedimentation of organic material as well as the flux of DMS to the atmosphere can be highly variable. Mapping of the horizontal and vertical distribution (in water and atmosphere) of the different sulfur and carbon compounds in the two different geographical areas will give information on the dynamics of these systems. Technical approach: Field data on sulfur and carbon compounds will be combined with data from incubation and process studies. A possible competitive advantage of Phaeocystis over other relevant spring bloom species in the uptake of CO2 will be linked to the metabolism of dimethylsulfoniopropionate (DMSP), the precursor of DMS, using axenic cultures. Biological removal processes of Phaeocystis-derived sulfur and carbon compounds will be studied in laboratory as well as on-board incubation experiments. The role of grazers as an intermediate in the degradation of a bloom and, thus, in the fate of carbon and sulfur, will be studied in experiments in the lab and in incubation studies in the field. During the course of a plankton bloom, stimulation of the bacterial community may result from the excretion of organic compounds or from cell rupture. A changing bacterial community structure will have implications for the degradation rate of Phaeocystis-derived organic material. In on-board incubation experiments, removal rates of various carbon and sulfur compounds will be measured. A differentiation between metabolic routes will be examined using specific inhibitors. With the development and application of molecular probes a differentiation of bacterial and algal DMSP-lyases (enzymes that are responsible for the conversion of DMSP into DMS and acrylic acid) can be established. Achievements: Process studies and field campaigns are expected to result in a better understanding of the role of Phaeocystis blooms in the escape of DMS to the atmosphere and of carbon from the photic zone. A conceptual model which mirrors the processes described in the study will allow an estimation of the impact of Phaeocystis dominated ecosystems on global climate. Ámbito científico natural sciencesearth and related environmental sciencesgeologysedimentologynatural scienceschemical sciencesorganic chemistrynatural sciencesbiological sciencesmicrobiologybacteriologynatural sciencesearth and related environmental sciencesatmospheric sciencesclimatologyclimatic changesnatural sciencesbiological sciencesbiochemistrybiomoleculesproteinsenzymes Programa(s) FP4-MAST 3 - Specific programme of research and technological development in the field of marine science and technology, 1994-1998 Tema(s) 020102 - Structure and dynamics of shelf ecosystems Convocatoria de propuestas Data not available Régimen de financiación CSC - Cost-sharing contracts Coordinador UNIVERSITY OF GRONINGEN Aportación de la UE Sin datos Dirección 30,Kerklaan 30 9751 NN HAREN GN Países Bajos Ver en el mapa Coste total Sin datos Participantes (4) Ordenar alfabéticamente Ordenar por aportación de la UE Ampliar todo Contraer todo Centre National de la Recherche Scientifique (CNRS) Francia Aportación de la UE Sin datos Dirección Avenue de la Terrasse 91198 Gif-sur-Yvette Ver en el mapa Coste total Sin datos NERC Centre of Coastal and Marine Sciences Reino Unido Aportación de la UE Sin datos Dirección Prospect Place West Hoe PL1 3DH Plymouth Ver en el mapa Coste total Sin datos UNIVERSITY OF EAST ANGLIA Reino Unido Aportación de la UE Sin datos Dirección University Plain NORWICH Ver en el mapa Enlaces Sitio web Opens in new window Coste total Sin datos UNIVERSITY OF TROMSOE Noruega Aportación de la UE Sin datos Dirección 201 B,Breivika 9037 TROMSOE Ver en el mapa Coste total Sin datos
