Helle Ploug
About Helle Ploug
Education M. Sc. in Biology and Chemistry, University of Aarhus, Denmark, 1992. Supervisor: Prof. Dr. Bo Barker Jørgensen Ph. D. in Microbial Ecology, University of Aarhus, Denmark, 1996. Supervisor: Prof. Dr. Bo Barker Jørgensen. Docent in Marine Ecology, Stockholm University, 2012
Professional experience Max Planck Post-doctoral Fellow, Max PIanck Institute for Marine Microbiology (MPI), Bremen (10/96-08/98) Carlsberg Fellow, Marine Biological Laboratory, University of Copenhagen (8/98-8/01) Alexander von Humboldt Fellow, MPI-Bremen (08/01-10/02) Maternity leave (100%: 10/02-9/03) Alexander von Humboldt Fellow, MPI-Bremen (09/03-12/04) Maternity leave (100%: 01/05-01/06) Scientist, Alfred-Wegener-Institute for Polar and Marine Research, Division for Marine Biogeoscience, Bremerhaven (01/06-08/08) Marie Curie Fellow, Stockholm University, Dept. of Botany (08/08-02/11) (75%: 25% maternity leave) Researcher, Stockholm University, Dept. of Systems Ecology (02/11-03/12) (100% permanent position) Associate Professor, University of Gothenburg (03/12-06/13)(100% permanent position) Professor, University of Gothenburg (06/13-present)(100% permanent position)
Research interests • Carbon and nutrient uptake (inc. N2-fixation) in phytoplankton • Remineralization and transport of carbon and nutrients in the water column • Small-scale fluxes, aggregate and colony formation, and chemical microenvironments in plankton • Linking small-scale and large-scale carbon and nutrient fluxes in plankton • Vertical carbon fluxes, marine snow, and the ocean’s biological carbon pump • The global carbon and nitrogen cycles in the ocean
CURRENT RESEARCH PROJECTS AS PRINCIPAL INVESTIGATOR
“Carbon and nitrogen fluxes associated with large cyanobacteria of the Baltic Sea - small-scale processes and their large-scale implications” funded by The Swedish Research Council for Environment, Agricultural Sciences, and Spatial Planning, FORMAS, 2011-2013:
In the Baltic Sea proper, N2-fixation contributes with a yearly N input larger than the entire riverine load. Summer blooms by filamentous, N2-fixing cyanobacteria are dominated by Nodularia sp., Aphanizomenon sp., and Anabeana sp. in the Baltic Sea. Aphanizomenon sp. blooms 2 to 3 months each summer. Using novel technology (combining nansocale secondary ion mass spectrometry, elemental analysis mass spectrometry, and microsensors) we recently demonstrated that this cyanobacterium may contribute between 50-100% of total yearly N2-fixation in the Baltic Sea of which at least one third is directly released as NH4+ to the surrounding water during N2-fixation. This cyanobacterium may, thus, supply other phytoplankton species and heterotrophic organisms with a substantial fraction of their N-demand during the whole summer season in the Baltic Sea. The present project aims at quantifying the N2 fixation associated with various cyanobacteria and to quantify NH4+ production by cyanobacteria relative to other sources (remineralization) during the seasons in the Baltic Sea.
Personnel: Post-doc Nurun Nahar (GU), Ph. D. stud. Malin Olofsson (GU), Ph. D. stud. Isabell Klawonn (SU), Ph. D. stud. Jennie Svedén (SU), Research Assistant Björn Andersson.
Collaborators: Peter Tiselius (GU), Niculina Musat (UFZ Leipzig, Germany), Ph. D. stud Birgit Adam, Gaute Lavik and Marcel Kuypers (MPI-Bremen, Germany).
Further reading: Ploug, H. 2008. Cyanobacterial aggregates formed by Aphanizomenon sp. and Nodularia spumigena in the Baltic Sea: Small-scale fluxes, pH and oxygen microenvironments. Limnol. Oceanogr. 53: 914-921. Ploug, H., Musat, N., Adam, B., Moraru, C.M., Lavik, G., Vagner, T., Bergman, B., Kuypers, M.M.M. 2010. Carbon and nitrogen fluxes associated with the cyanobacterium Aphanizomenon sp. in the Baltic Sea. The ISME-Journal 4: 1215-1223. doi:10.1038/ismej.2010.53. Ploug, H., Adam, B., Musat, N., Kalvelage, T., Lavik, G., Wolf-Gladrow, D. and Kuypers, MMM. 2011. Carbon, nitrogen, and O2 fluxes associated with the cyanobacterium Nodularia spumigena in the Baltic Sea. The ISME-Journal 5: 1549-1558 doi:10.1038/ismej.2011.20.
“Diatoms and the ocean’s biological carbon pump” funded by the Swedish Research Council (VR) 2012-2015:
Diatoms play a key role in the carbon cycling on earth. Diatom blooms dominate in cold, nutrient-rich environments with high shear, e.g., spring blooms in temperate regions and in highly productive upwelling regions where cold, nutrient-rich water from the deep sea reaches the euphotic zone of the ocean where it gives rise to phytoplankton growth. These blooms are terminated with the formation of fast-sinking aggregates (> 0.5 mm), which comprise a significant component of vertical carbon fluxes to the deep sea and sediments. Hence, diatoms play a significant role in the biological carbon sequestration by the ocean and export of fixed CO2 as organic matter to the deep-ocean and sediments, i.e., the biological carbon pump. The project aims at new understanding and direct quantification of the processes controlling carbon assimilation and nutrient uptake, aggregate formation and degradation in chain-forming diatoms using novel techniques. Combining microsensor and Secondary Ion Mass Spectrometry (SIM) techniques we will directly quantify carbon and nutrient assimilation by chain-forming diatoms in laminar shear at levels similar to those encountered by in the surface ocean as well as the transport and degradation of C and N in sinking diatom aggregates. We will also directly quantify to which extent motile bacteria can cover their carbon and nutrient demand by exploitation of nutrient patches associated with sinking aggregates
Personnel: Post-doc Johanna Bergkvist (GU), Research assistant Björn Andersson (GU)
Collaborators: Hans-Peter Grossart (IGB- Berlin), Niculina Musat (UFZ, Leipzig), Bo Liu and Arzhang Khalili (MPI-Bremen), Gerhard Fischer and Morten Iversen (Marum, Bremen), Eva-Maria Zetsche (NIOZ, Yerseke), Erik Selander (GU)
Further reading: Ploug H, Grossart H-P. 2000. Bacterial growth and grazing on diatom aggregates: Respiratory carbon turnover as a function of aggregate size and sinking velocity. Limnol. Oceanogr. 45 (7): 1467-1475. Kiørboe T, Ploug H, Thygesen UH. 2001. Fluid motion and solute distribution around sinking marine snow aggregates: Small scale fluxes and heterogeneity of nutrients in the pelagic environment. Mar. Ecol. Prog. Ser. 211: 1-13. Grossart H-P, Ploug H. 2001. Microbial degradation of organic carbon and nitrogen on diatom aggregates. Limnol. Oceanogr. 46 (2): 267-277. Ploug H. 2001. Small-scale oxygen fluxes and remineralization in sinking aggregates. Limnol. Oceanogr. 46 (7): 1624-1631. Ploug H, Iversen MH, Fischer G. 2008. Ballast, sinking velocity and apparent diffusivity in marine snow and zooplankton fecal pellets: Implications for substrate turnover by attached bacteria. Limnol. Oceanogr. 53; 1878-1886.
Publications Lassen C, Ploug H, Jørgensen BB. 1992. A fibre-optic scalar irradiance sensor: applications for spectral light measurements in sediments. FEMS Microbiol. Ecol. 86: 247-254. Lassen C, Ploug H, Jørgensen BB. 1992. Microalgal photosynthesis and spectral scalar irradiance in coastal marine sediments of Limfjorden, Denmark. Limnol. Oceanogr. 37: 760-772. Ploug H, Lassen C, Jørgensen BB. 1993. Action spectra of microalgal photosynthesis and depth distributions of spectral scalar irradiance in a coastal marine sediment of Limfjorden, Denmark. FEMS Microbiol. Ecol. 102: 261-270. Ploug H, Lassen C, Jørgensen BB. 1993. Action spectra of microalgal photosynthesis and depth distributions of spectral scalar irradiance in a coastal marine sediment of Limfjorden, Denmark. FEMS Microbiol. Ecol. 12: 69-78. Lassen C, Ploug H, Kühl M, Jørgensen BB. 1994. Oxygenic photosynthesis and light distribution in marine microbial mats. In: L. J. Stal and P. Caumette (eds.) Microbial mats: Structure, development and environmental significance. NATO ASI Series Vol. G 35: 305-311. Springer-Verlag. Kühl M, Glud RN, Ploug H, Ramsing NB. 1996. Microenvironmental control of photosynthesis and photosynthesis-coupled respiration in an epilithic cyanobacterial biofilm. J. Phycol. 32: 799-812. Ploug H, Kühl M, Buchholz B, Jørgensen BB. 1997. Anoxic aggregates – an ephemeral phenomenon in the ocean. Aquat. Microbol. Ecol. 13: 285-294. Ploug H, Jørgensen BB. 1999. A net-jet flow system for mass transfer and microelectrode studies in sinking aggregates. Mar. Ecol. Prog. Ser. 176: 279-290. Ploug H, Grossart H-P, Azam F, Jørgensen BB. 1999. Photosynthesis, respiration, and carbon turnover in sinking marine snow from surface waters of Southern California Bight: Implications for the carbon cycle in the ocean. Mar. Ecol. Prog. Ser. 179: 1-11. Schramm A, Santegoeds CM, Nielsen HK, Ploug H, Wagner M, Pribyl M, Wanner J, Amann R, deBeer D. 1999. An interdisciplinary Approach to the Occurrence of Anoxic Microniches, Denitrification, and Sulfate Reduction in Aerated Activated Sludge. Appl. Environ. Microbiol. 65:4189-4196. Ploug H, Grossart H-P. 1999. Bacterial production and respiration in aggregates - a matter of the incubation method. Aquat. Microbol. Ecol. 20(1): 21-29. Ploug H, Stolte W, Epping EHG, Jørgensen BB. 1999. Diffusive boundary layers, photosynthesis and respiration of the colony-forming plankton alga, Phaeocystis sp. Limnol. Oceanogr. 44(8): 1949-1958. Ploug H, Stolte W, Jørgensen BB. 1999. Diffusive boundary layers of the colony-forming plankton alga, Phaeocystis sp. – implications for nutrient uptake. Limnol. Oceanogr. 44(8): 1959-1967. Ploug H, Stolte W, Jørgensen BB. 2000. Diffusive boundary layers of the colony-forming plankton alga, Phaeocystis sp. – implications for nutrient uptake. (Correction) Limnol. Oceanogr. 45(4): 1012. Grossart H-P, Ploug H. 2000. Bacterial Production and Growth Efficiencies: Direct Measurements on Riverine Aggregates. Limnol. Oceanogr. 45 (2): 436-445. Ploug H, Grossart H-P. 2000. Bacterial growth and grazing on diatom aggregates: Respiratory carbon turnover as a function of aggregate size and sinking velocity. Limnol. Oceanogr. 45 (7): 1467-1475. Kiørboe T, Ploug H, Thygesen UH. 2001. Fluid motion and solute distribution around sinking marine snow aggregates: Small scale fluxes and heterogeneity of nutrients in the pelagic environment. Mar. Ecol. Prog. Ser. 211: 1-13. Grossart H-P, Ploug H. 2001. Microbial degradation of organic carbon and nitrogen on diatom aggregates. Limnol. Oceanogr. 46 (2): 267-277. Ploug H. 2001. Small-scale oxygen fluxes and remineralization in sinking aggregates. Limnol. Oceanogr. 46 (7): 1624-1631. Ploug H, Zimmermann-Timm H, Schweitzer B. 2002. Microbial communities and respiration on aggregates in the Elbe estuary, Germany. Aquat. Microbial Ecol. 27: 241-248. Ploug H, Hietanen S, Kuparinen J. 2002. Diffusion and advection within and around sinking, porous diatom aggregates. Limnol. Oceanogr. 47 (4): 1129-1136 Kiørboe T, Grossart H-P, Ploug H, Tang K. 2002. Mechanisms and rates of bacterial colonization of sinking aggregates. Appl. Environ. Microbiol. 68 (8) 3996-4006. Simon M, Grossart H-P. Schweitzer B, Ploug H. 2002. Microbial Ecology of Organic Aggregates in Aquatic Ecosystems. (Review). Aquat. Microbial. Ecol. 28 (2): 175-211. Grossart H-P, Hietanen S, Ploug H. 2003. Microbial dynamics on natural diatom aggregates in Øresund, Denmark. Mar. Ecol. Prog. Ser. 249: 69-78. Thorsen MS, Wieland A, Ploug H, Kragelund C, Nielsen PH. 2003. Distribution and activity of endosymbiotic sulfur bacteria in anoxic aggregates from the hindgut of the sea urchin Echinocardium cordatum, Ophelia 57: 1-12. Kiørboe, T, Tang, K, Grossart, H.-P., Ploug, H. 2003. Microbial dynamics on marine snow: colonization, growth, detachment, and mortality of attached bacteria. Appl. Environ. Microbiol. 69(6): 3036-3047. Grossart, H-P, Kiørboe T, Tang K, Ploug H. 2003.Bacterial Colonization of Marine Snow Particles: Growth and Inter-Specific Interactions Appl. Environ. Microbiol. 69(6): 3500-3509. Passow U, Engel A, Ploug H. 2003. The Role of Aggregation for the Dissolution of Diatom Frustules. FEMS Microb Ecol 46: 247-255. Ploug, H. 2004. Snow in the Ocean. Humboldt Kosmos. 83:27. Kiørboe, T, Grossart H.-P., Ploug H, Tang K, Auer B. 2004. Particle associated flagellates: swimming patterns, colonization rates, and grazing on attached bacteria. Aquat. Microb Ecol. 35:141-152. Grossart HP, Kiørboe T, Tang KW, Allgaier M, Yam EM, Ploug H. 2005. Interactions between marine snow and heterotrophic bacteria: aggregate formation and microbial dynamics. Aquat. Microb Ecol. 42: 19-26. Ploug H, Passow U. 2007. Direct measurements of diffusivity in diatom aggregates containing transparent exopolymer particles (TEP). Limnol. Oceanogr. 52: 1-6. Grossart HP, Tang, KW, KiørboeT, Ploug H. 2007. Comparison of cell-specific activity between free-living and attached bacteria using isolates and natural assemblages. FEMS Microbiol. Lett. 266: 194-200. Ploug H, Iversen, MH, Koski M, Buitenhuis ET. 2008. Production, respiratory carbon turnover, and sinking velocity of copepod fecal pellets: direct measurements of ballasting by opal and calcite. Limnol. Oceanogr. 53: 469-476. Dehairs, F. (ed), deBrauwere, A. (ed), Elskens, M. (ed), Bathmann, U., Becquevort, S., Blain, S., Boyd, P., Buesseler, K., Buitenhuis, E., Gehlen, M., Herndl, G., Klaas, C., Lampitt, R., Lefevre, D., Passow, U., Ploug, H., Primeau, F., Stemmann, L., Trull, T., 2008. Controls on Organic Carbon Export and Twilight Zone Remineralization. Oceanography, 21, 94-97. Ploug, H. 2008. Cyanobacterial aggregates formed by Aphanizomenon sp. and Nodularia spumigena in the Baltic Sea: Small-scale fluxes, pH and oxygen microenvironments. Limnol. Oceanogr. 53: 914-921. Ploug H, Iversen MH, Fischer G. 2008. Ballast, sinking velocity and apparent diffusivity in marine snow and zooplankton fecal pellets: Implications for substrate turnover by attached bacteria. Limnol. Oceanogr. 53; 1878-1886. Iversen MH, Nowald N, Ploug H, Jackson GA, Fischer, G. 2010. High resolution profiles of vertical particulate organic matter export off Cape Blanc, Mauritania: Degradation processes and ballasting effects. Deep-Sea Res. I. 57:771-784. doi: 10.1016/j.dsr.2010.1003.1007 Ploug, H., Musat, N., Adam, B., Moraru, C.M., Lavik, G., Vagner, T., Bergman, B., Kuypers, M.M.M. 2010. Carbon and nitrogen fluxes associated with the cyanobacterium Aphanizomenon sp. in the Baltic Sea. The ISME-Journal 4: 1215-1223. doi:10.1038/ismej.2010.53. Feature Article Ploug, H, Terbrüggen A, Kaufmann A, Wolf-Gladrow D, Passow U. 2010. A novel method to measure particle sinking velocity in vitro, and its comparison to three other in vitro methods. Limnol. Oceanogr.-Methods 8: 386-393. DOI 10:4319/lom.2010.8.386 Iversen MH, Ploug H. 2010. Ballast minerals and the sinking carbon flux in the ocean: Carbon-specific respiration rates and sinking velocities of marine snow aggregates. Biogeosciences 7: 2613-2624. doi:10.5194/bg-7-2613-2010 Ploug, H., Adam, B., Musat, N., Kalvelage, T., Lavik, G., Wolf-Gladrow, D. and Kuypers, MMM. 2011. Carbon, nitrogen, and O2 fluxes associated with the cyanobacterium Nodularia spumigena in the Baltic Sea. The ISME-Journal 5: 1549-1558 doi:10.1038/ismej.2011.20. Svedén, J, and Ploug, H. 2012 “Kvävefixerare göder haven” Havsutsikt 2: 12-13. Iversen, MH. and Ploug, H. 2013. Temperature effects on carbon-specific respiration rate and sinking velocity of diatom aggregates. Potential implications for deep ocean export processes. Biogeosciences.10:4073-4085. Klawonn, I, Bonaglia, S, Brüchert, V, and Ploug, H. Anaerobic N-cycling in N2 fixing Cyanobacterial colonies (under review). Ploug, H, and Bergkvist, J. Hypoxia can stimulate NH4+ release by sinking diatom aggregates (under review).
Google scholar publication/citations: http://scholar.google.com/citations?user=y9SMpDwAAAAJ