Ongoing Research Projects

• Invasive Marine Species – How abundant are they on large scales? Marine invasions can have dramatic impact on natural ecosystems. However, most studies have been conducted on relatively small spatio-temporal scales. I use an extensive data set from the Danish National Marine Monitoring Program to investigate how abundant non-native species are on broad scales. These data are also used to compare ecologies of introduced and native species.
• Gracilaria – A Model Invader . Gracilaria spp. are ubiquitous macroalgae in shallow low energy temperate coastal ecosystems worldwide. Various Gracilaria species has been introduced to several continents as both cryptic and conspicuous invaders and on different dispersal vectors. Gracilaria is also stress resistant and often facilitated by native invertebrates. Distribution patterns, recruitment, growth, biological interactions and ecological impacts are compared between introduced and native Gracilaria species on different continents to better understand marine invasions.
• Ecology and Impacts of Drift Algae . Drift algae often accumulate into large mats in low energy estuaries, typically facilitated by anthropogenic sedimentation, global warming and in particular eutrophication. Such accumulations can, particularly if they decompose, have negative impacts on seagrass beds, benthic animals and human beach-visitors. I study the origin, stability and density-decomposition thresholds of such algal mats, as well as impacts on seagrasses and benthic invertebrates.
• Invertebrate-Algal Facilitation . Facilitation processes are increasingly included into ecological theory. I research how ubiquitous invertebrates, such as polychaetes and mollusks, create structural complex mini-reefs in soft-bottom ecosystems and thereby create islands of hard substrata suitable for inhabitation by sessile species. The appreciation of facilitation processes in general, and these diverse and productive biogenic mini-reefs in particular, are important for conservation and management of soft-bottom estuaries and lagoons.
• Biomechanical and hydrodynamic links to distribution patterns . Tidal currents and storm waves often dislodge entire macroalgae or prune them down in size. Research projects involve linking hydrodynamic forces and biomechanical properties to ecological distribution patterns of both sessile and unattached macroalgal populations.
• Caulerpa spp. – Are they superior invaders? Certain species of Caulerpa (macroalgae) have received high scientific and public attention because they are considered among the world’s worst biological invaders. Distribution patterns and ecological traits of invasive and non-invasive Caulerpa species are compared from their place of origin to better understand what traits make some species invasive compared to other.
• Impacts of anthropogenic stressors on Australasian Salt Marshes . Impacts of anthropogenic stressors on intertidal salt marshes have long been investigated in North America and Europe. Comparatively little is know about impacts in Australasian salt marshes, and results cannot automatically be extrapolated due to differences in species compositions and pedology. Manipulative experiments are used to test if anthropogenic stressors - nutrient enrichment in particular - affect species distribution and zonation in Australasian salt marshes.

 

Other activities

• Organization of Danish/Scandinavian Invasive Marine Species Symposium . Marine invasions have been studied intensively throughout the world. However, this research topic has largely been neglected in Denmark. To increase awareness about marine invasions I am organizing a one day symposium to be held in Copenhagen, August 2007. Expected topics include introductory talks and commentaries, overview presentations, case-studies, and a poster session. Basic and applied research, literature reviews and administration/management topics are welcome. Interested participants and presenters should contact me on email. Although emphasis is on Danish conditions, participation from neighboring countries is encouraged. Announcements regarding symposium date, deadlines, pricing and location will be posted on this web-site later.

 

Links to External Collaborators

Karen McGlathery (Department of Environmental Sciences, University of Virginia, USA) [http://faculty.virginia.edu/mcglathery/]

Thomas Wernberg ( School of Natural Sciences, Edith Cowan University, Australia) [http://www.sons.ecu.edu.au/staff/twernberg.php]

Fernando Tuya ( School of Natural Sciences, Edith Cowan University, Australia) [http://www.sons.ecu.edu.au/staff/ftuya.php]

Dorte Krause-Jensen (Department of Marine Ecology, National Environmental Research Institute, Denmark) [http://www2.dmu.dk/1_om_dmu/2_afdelinger/3_hav/person.asp?PersonID=DKJ]

Peter Anton Stæhr ( Institute of Biology, Freshwater Biological Laboratory, University of Copenhagen, Denmark) [http://www.bi.ku.dk/staff/person.asp?ID=106]

Jens Borum ( Institute of Biology, Freshwater Biological Laboratory, University of Copenhagen) [http://www.bi.ku.dk/staff/person.asp?ID=66]

 

Thomsen embedded in a drift-algal mat composed of the highly invasive Gracilaria vermiculophylla. G. vermiculophylla has invaded numerous European countries and both the east and west coast of the US.

 

Thomsen conducting biomechanical breakage tests on Ecklonia radiata, a dominant kelp in Australasia. Such data are used to predict kelp survival during storms.

 

Gracilaria attached to a tagged and partly buried Battilaria australis. This gastropod is ubiquities in Swan estuary ( Australia) providing amble substratum for fixed populations of Gracilaria and its associated epibiota. Analogue biogenic mini-reefs are studied in the US, Denmark and New Zealand.

 

Recent Publications (2004 - present)

Thomsen, M.S. , Wernberg, T., Stæhr, P.A., Krause-Jensen, D. Risgaard-Petersen, N., Silliman, B.R. (In revision). Alien macroalgae in Denmark – a broad-scale national perspective. Marine Biology Research.

 

Thomsen, M.S. , K. McGlathery, B. Silliman. (In revision). Spatial variation in recruitment of native and invasive sessile species onto oyster reefs in a temperate soft-bottom lagoon. Estuarine, Coastal and Shelf Science .

 

Thomsen, M.S., Adam, P., Silliman, B.R. (In revision). Anthropogenic threats to Australasian coastal salt marshes. In Anthropogenic Modification of North American Salt Marshes (eds. B.R. Silliman, M.D. Bertness, D. Strong), Cambridge University Press.

 

Thomsen, M.S., McGlathery, K. ( In press). Stress tolerance of the invasive macroalgae Codium fragile and Gracilaria vermiculophylla in a soft-bottom turbid lagoon, Virginia. Biological Invasions.

 

Thomsen, M.S. , McGlathery, K., Tyler, C. ( 2006 ). Macroalgal distribution pattern in a shallow, soft-bottom lagoon, Virginia, with emphasis on the alien Gracilaria vermiculophylla and Codium fragile. Estuaries and Coasts 29: 465-473.

 

Thomsen, M.S. , Wernberg, T., Stæhr, P.A., Pedersen, M.F. ( 2006). Depth and substrate conditions determine the success of the invasive macroalgae Sargassum muticum in Limfjorden, Denmark. Helgoland Marine Research 60: 50-58.

 

Thomsen, M.S. , McGlathery, K. ( 2006 ). Effects of accumulations of sediments and drift algae on recruitment of sessile organisms associated with oyster reefs. Journal of Experimental Marine Biology and Ecology 328: 22-34.

 

Thomsen, M.S. , Gurgel, C.F.D., Fredericq, S., McGlathery, K.J. ( 2005). Gracilaria vermiculophylla (Rhodophyta, Gracilariales) in Hog Island Bay, Virginia: a cryptic alien and invasive macroalgae and taxonomic corrections. Journal of Phycology 42: 139-141.

 

Thomsen, M.S., Wernberg, T. ( 2005 ). Minireview: What affects the forces required to break or dislodge macroalgae?. European Journal of Phycology 40: 1-10.

 

Thomsen, M.S. , McGlathery, K. ( 2005) . Facilitation of macroalgae by the sedimentary tube forming polychaete Diopatra cuprea. Estuarine, Coastal and Shelf Science 62: 63-73.

 

Thomsen, M.S. , Krause-Jensen, D., Wernberg, T., Stæhr, P.A, Risgaard, N.P. (2005 ). Fremmede tangarter i Danmark: Hvilke, hvornår og hvor udbredte? (Alien seaweeds in Denmark: which, when and how abundant?). URT (Danish Botanical Journal) 29: 110-115.

 

Wernberg, T., Thomsen, M.S. ( 2005 ). The effect of wave exposure on the morphology of Ecklonia radiata in southwestern Australia. Aquatic Botany 83: 61-70.

 

Pedersen, M.F., Stæhr, P.A., Wernberg, T., Thomsen, M.S. (2005 ). Biomass dynamics of exotic Sargassum muticum and native Halidrys siliquosa in Limfjorden, Denmark - implications of species replacements on turnover rates. Aquatic Botany 83: 31-47.

 

Thomsen, M.S. , Wernberg, T., Kendrick, G. ( 2004 ). The effect of thallus size, life stage, aggregation, wave exposure and substrate conditions on the forces required to break or dislodge the small kelp Ecklonia radiata. Botanica Marina 47: 454-460.

 

Thomsen, M.S. ( 2004) . Species, thallus size and substrate determine macroalgal break forces and break places in a low energy soft bottom lagoon. Aquatic Botany 80: 153-161.

 

Wernberg, T., Thomsen, M.S., Stæhr, P.A., Pedersen, M.F. (2004). Epibiota communities of the introduced and indigenous macroalgal relatives Sargassum muticum and Halidrys siliquosa in Limfjorden ( Denmark). Helgoland Marine Research 58: 154-161.

Mads Solgaard Thomsen

Professional Affiliation

International Postdoctoral Fellow (Marine Bioinvasions); Silliman Lab, Department of Zoology, University of Florida

Email: mads_thomsen [AT] mailcity.com

Other Affiliation ( Adjunct Lecturer)

Edith Cowan University, Faculty of Computing, Health and Science, School of Natural Sciences, Joondalup Campus, 100 Joondalup Drive, Joondalup, Western Australia 6027, Australia, Office: 19.121, Phone: +61 8 6304 5674, Fax: +61 8 6304 5762

Education

Ph.D. Environmental Sciences, University of Virginia, USA (2004). Thesis title: Macroalgal distribution patterns and ecological performances in a tidal coastal lagoon, with emphasis on the non-indigenous Codium fragile ssp. tomentosoides. Download thesis.

M.Sc. Environmental Biology & Geography, Roskilde University, Denmark (1998). Thesis title: Studies on the ecology of Sargassum muticum (Yendo) Fensholt in Limfjorden.

Research Interests

I am a coastal ecologist that primarily have studied plant and animal communities on and around temperate reefs, including stone reefs in Denmark, oysters and polychaete reefs in USA, limestone reefs in Australia and bivalve reefs in New Zealand. My research focuses, to a large extent, on how anthropogenic stressors, such as introduction of non-native species, eutrophication, enhanced sedimentation, and global warming, impact structure and productivity of marine communities, and I use manipulative experiments to test how patterns in biological communities are generated and maintained.

I am particularly interested in facilitation processes that increasingly are found to influence marine community structure, and therefore should be included in coastal management and conservation. This research provides predictions on how coastal habitats will respond to anthropogenic stressors and recommendations for conservation strategies needed to ameliorate their impacts. Above topics are studied with collaborators at field sites in Denmark, USA, Western Australia and New Zealand.