Tvärminne Zoological Station has an over a century long history of scientific research, with emphasis on the brackish waters of the Gulf of Finland. The station was established in 1902 and thus provides good background data for studying long-term environmental change. Marine research at TZS focuses on the biodiversity and functioning of the Baltic Sea ecosystem, and the effects of anthropogenic stressors, such as eutrophication, climate change and ocean acidification. Evolutionary and population biology are also important topics, encompassing the social, sexual, and genetic structure of colony-forming insects, sexual selection and reproductive biology in fish and birds, and the dispersion and reproduction of insects and rock-pool organisms in fragmented landscapes (metapopulation biology).