Tvärminne Zoological Station (TZS) was established in 1902 and belongs to the Faculty of Biological and Environmental Sciences of the University of Helsinki (UH), which is the Finnish partner in ASSEMBLE Plus. TZS is located at the entrance to the Gulf of Finland in the Baltic Sea. It provides good background data for studying long-term environmental change. One of the weather stations of the Finnish Meteorological Institute is located at TZS. TZS serves as a centre for a variety of high-quality biological research, carries out environmental monitoring, and offers facilities for visiting scientists, field courses and seminars. Marine research at TZS focuses on the biodiversity and functioning of the Baltic Sea ecosystem and the anthropogenic stressors affecting the system. The research covers ecology, ecophysiology, ecotoxicology, taxonomy, and behavioural and evolutionary biology.


  • Baltic Sea ecosystems (brackish water ecosystems characterised by vast archipelagos with high habitat complexity)


Ecosystem access

  • Two research vessels R/V Saduria (14.4 m) and R/V J.A. Palmén (10.3 m)
  • Smaller boats for coastal sampling
  • Hovercraft for winter sampling
  • Diving facilities
  • Standard sampling equipment such as water samplers, plankton nets, sediment corers and grabs, dredges and trawls, and handheld probes (CTD, oxygen)


Biological resources

  • Access to the FINMARI culture collection is also offered, with 220 strains of Baltic Sea phytoplankton


Experimental facilities and technology platforms

  • Well-equipped laboratory with flow-through seawater
  • Aquarium rooms
  • An isotope laboratory (class C isotope laboratory)
  • Equipment for large-scale field experiments
  • TZS is classified as University of Helsinki facility for experiments with animals (fish)


Associated services (E-services, Expert advice, Supporting faciltites)

  • Long-term monitoring data from the TZS area is available on temperature, salinity, nutrients, chlorophyll, zooplankton and benthic macrofauna

The station is operational all year around. TZS offers accommodation for more than 80 people at a time. 


J.A. Palmenin tie 260
10900 Hanko
Liaison officer: Joanna Norkko (, cc to:

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