Marcel Veldhuis Senior Scientist	ROYAL NETHERLANDS INSTITUTE FOR SEA RESEARCH   Postal address: P.O. Box 59, NL-1790 AB Den Burg (Texel) The Netherlands   Visiting address: Landsdiep 4 NL-1797 SZ ’t Horntje (Texel) The Netherlands   Phone: (+31) (0)222-369300 Fax: (+31) (0)222-319674
E-mail: marcel.veldhuis@nioz.nl   Phone: (+31) (0)222-369512
Phaeocystis globosa, love of my (professional) life
I am trained as a microbiologist but have been involved in phytoplankton research from 1983 onwards. My scientific career started with an ecological and physiological study of the colony forming phytoplankter Phaeocystis globosa,  a common phytoplankter present in the coastal zone of the North Sea (Ph-D project University of Groningen). This algal species belongs to the Harmful Algal Blooms because of the nuisance it causes for (shell)fish but it also produces lots of foam on the beaches.   ……
Flow cytometry
In the late eighties new tools, like flow cytometry (a rapid cell counting and identification technique), became available allowing the study of very small phytoplankton (< 2 mm) in the open oceans. Combined with other techniques like plant pigment analysis it is now possible to identify these ‘unknowns’ but also to determine their growth and fate. The main focus in phytoplankton research became the interspecific variability of the phytoplankton community (differences between co-occurring phytoplankton species) and how this is translated in terms of species succession and dominance. With the introduction of new (molecular) tools to examine in situ also the physiological properties of a single cell could be determined, e.g. is the cell still active or already dead. As a result research was further focussed on the intraspecific variability (differences within a single species). This approach turned to be very successful in the case of Phaeocystis, a phytoplankter with totally different cell types (small single cells and big colonies full with cells) co-occurring. Because growth of phytoplankton is controlled by a huge variety of different environmental factors there is a close collaboration with physicists (light); chemists (nutrients like nitrogen, phosphorus and silicate but also micronutrients like iron) but also colleague biologist studying the mortality due to grazing or death because of a virus infection. All these bits and pieces of our field and laboratory research is combined in complex models used to enhance our understanding of the ecosystem as a whole. The main research areas are quite diverse and include the Dutch Wadden Sea (long-term series), North Sea but also the open oceans, the latter are studied during cruises onboard of different research vessels. These projects are often complemented with detailed laboratory experiments, e.g. in large mesocosms (850 l). ……
Student opportunities
For those whole are looking for research projects and are interested in marine phytoplankton research do not hesitate to contact me for further information. Ben je geinteresseerd in een stage of studie onderwerp op het gebied van marien fytoplankton, neem dan even contact met mij op om te zien wat er allemaal mogelijk is. Email address: Veldhuis at NIOZ.nl
Phaeocystis globosa
A phytoplankton species belonging to the group of Harmful Algal Blooms which is of great nuisance every year in spring along the Belgium, Dutch and German coast of the North Sea. The single cells are rather small (4 – 6 mm) but the colonies up to 1 cm contain a lot of gelatinous mucus forming a dense foam layer on the beaches at the end of the bloom period.         Large colonies of Phaeocystis globosa with thousands of small (ca. 4 mm in diameter) cells         At the end of the bloom of P. globosa the mucus of the colonies is found as foam on the beach
Publication list (past 5 years)
Buma, A.J.G., T. van Oijen, W. van de Pol, M.J.W. Veldhuis & W.W.C. Gieskes 2000 The sensitivity of the marine prymnesiophyte Emiliania huxleyi to Ultraviolet-B radiaton. J. Phycol. 36:296 – 303. Boelen, P., M,K, de Boer, G.W. Kraay, M.J.W. Veldhuis & A.G.J. Buma 2000 UVBR-induced DNA damage in natural marine picophytoplankton assemblages in the tropical Atlantic Ocean. Mar. Ecol. Progr. Ser. 193: 1 – 9. Timmermans, K.R., L.J.A. Gerringa, H.J.W. de Baar, B. van der Wagt, M.J.W. Veldhuis, J.T.M. de Jong & P.L. Croot. 2001 Growth rates of large and small southern Ocean diatoms in relation to availability of iron in natural seawater. —Limnol. Oceangr. 46: 260-266. Veldhuis, M.J.W. & G.W. Kraay 2000 Application of flow cytometry in marine phytoplankton research: current applications and future perspective. Sci Mar. 64: 121 – 134. Veldhuis, M.J.W., G.W. Kraay & K.R. Timmermans. 2001 Cell death in phytoplankton: correlation between changes in membrane permeability, photosynthetic activity, pigmentation and growth. —Eur. J. Phycol.  36 :  167 - 177. Timmermans, K.R., M.S. Davey, B. van der Wagt, J. Snoek, R.J. Geider, M.J.W. Veldhuis, L.J.A. Gerringa & H.J.W. de Baar. 2001 Co-limitation by iron and light of Chaetoceros brevis, C. dichaeta and C. Calictrans (Bacillariophyceae). —Mar. Ecol. Prog. Ser. 217: 287 – 297. Boelen. P., M.J.W. Veldhuis & A.G.J. Buma 2001 Accumulation and removal of UVBR-induced DNA damage in marine tropical plankton subjected to mixed and simulated non-mixed conditions. —Aquat. Microb. Ecol. 24: 265 – 274. Veldhuis, M.J.W. & K.R. Timmermans 2001.  Phytoplankton abundance and cellular properties during a iron fertilisation experiment in the Southern Ocean. Reports on Polar and Marine Research 400: 161 – 164. Veldhuis, M.J.W., G.W. Kraay & K.R. Timmermans. 2001. Cell death in phytoplankton: are they all alive? —Phycologia 40: 26. Boelen, P., A.F. Post, M.J.W. Veldhuis & A.G.J. Buma 2002 Diel patterns of UVBR-Induced DNA damage in picoplankton size fractions from the Gulf of Aqaba, Red Sea., Microbial  Ecology  44: 164 – 174. Claquin, P. Martin-Jézéquel, V., Kromkamp, J.C., Veldhuis, M.J.W., Kraay, G.W. 2002. Uncoupling of silicon compared to carbon and nitrogen metabolism and role of the cell cycle, in continuous cultures of Thalassiosira pseudonana (Bacillariophyceae), under light, nitrogen and phosphorus control. J. Phycol. 38: 922 – 930. Van Duyl, F.C., G.J. Gast, W. Steinhoff, S. Kloff, M.J.W. Veldhuis & R.P.M. Bak 2002 Factors influencing the short-term variation in phytoplankton composition and biomass in coral reef waters. Coral Reefs 21: 293 – 306. Boye, M., A.P. Aldrich, C.M.G. van den Berg, J.T.M. de Jong, M. Veldhuis & H.J.W. de Baar. 2003, Horizontal gradients of the chemical speciation of iron in the surface water of the northeast Atlantic Ocean. Marine Chemistry, 180: 129 – 143. Veldhuis, M.J.W. 2003 HABs imply that mortality is lower than growth. The EU-US Scientific Initiative on Harmful Algal Blooms: Report from a workshop jointly funded by the Research _ Environment Directorate and the U.S. National Science Foundation; EUR 20578: page 46. Veldhuis, M.J.W.,Kraay, G.W., 2004. Phytoplankton in the subtropical Atlantic Ocean: towards a better assessment of biomass and composition. Deep-Sea Research I 51, 507 - 530. Schultz, K.G., I. Zondervan, L.J.A. Gerringa, K.R. Timmermans, M.J.W. Veldhuis and U. Riebesell, 2004 Effect of trace metal availability on coccolithophorid calcification. Nature 430: 673-676. Ruardy, P., Veldhuis, M.J.W.,Brussaard, C.P.D., 2005. Modelling bloom dynamics of the polymorphic phytoplankter Phaeocystis globosa: impact of grazers and viruses. Harmful Algae  in press Timmermans, K.R., Wagt, B.v.d., Veldhuis, M.J.W., Maatman, A.,Baar, H.J.W.d., 2005. Physiological responses of three species of marine pico-phytoplankton to ammonium, phosphate, iron and light limitation. Journal of Sea Research 53: 109 - 120. Veldhuis, M.J.W., Brussaard, C.P.D.,Noordeloos, A.A.M., 2005. Living in a Phaeocystis colony; a way to be a succesful algal species. Harmful Algae in press Veldhuis, M.J.W.,Wassmann, P., 2005. Bloom dynamics and biological control of a high biomass HAB species in European coastal water: a Phaeocystis case study. Harmful Algae Oijen, T. van, M.J.W. Veldhuis, M.Y. Gorbunov, J. Nishioka, M.A. van Leeuwe and H.J.W. de Baar, 2004 Enhanced carbonate production by Southern Ocean phytoplankton in response to in situ fertilisation. Mar. Chemistry. In press. Jacobsen, A. and M. J.W. Veldhuis 2005 Growth characteristics of flagellated cells of Phaeocystis pouchetii revealed by diel changes in cellular DNA content; effects of different light:dark periods, light intensities, N:P ratios and temperature. Harmful Algae, in press Brussaard C. P. D., X. Mari, J.D.L. Van Bleijswijk, M.J.W. Veldhuis, 2005. A mesocosm study of Phaeocystis globosa population dynamics. II. Significance for the microbial food web. Harmful Algae, in press Brussaard C. P. D., B. Kuipers, M.J.W. Veldhuis, 2005. A mesocosm study of Phaeocystis globosa population dynamics. I. Regulatory  role of viruses in bloom control. Harmful Algae, in press Veldhuis, M.J.W., K.R. Timmermans, P. Croot and B. van der Wagt, 2005 Picophytoplankton; a comparative study of their biochemical composition and photosynthetic properties. J. Sea Res. 53: 7 – 24.