The First General Assembly of each congress of the Societas Internationalis Limnologiae culminates with the award of the Einar Naumann - August Thienemann Medals. This award is the highest honor that can be bestowed internationally for outstanding scientific contributions to limnology. The engraved bronze medal bears the reliefs of the two founders of SIL and the meritorious inscription in Latin cited above. The Naumann-Thienemann Medal Committee evaluates nominations received from the membership and submits its recommendations to the International Committee for approval. Not more than one medal shall be awarded per year (see Statutes of SIL in the Appendices of the General Secretary's Report of the Proceedings).
The medal originated as the Einar Naumann Medal and was first awarded in 1948 (see listing of recipients at the end of this article). The important contributions of August Thienemann to the development and leadership of SIL were fully appreciated later when the early records of the SIL were examined carefully (see Rodhe, 1974, for a detailed account of the events, original correspondence, and meetings that led to the foundation of SIL in 1922). In 1972, at an international workshop to honor the 50th anniversary of the SIL (Wetzel 1974), a decision was made to alter the medal to recognize the different, but fundamental and reinforcing, contributions of both scientists to international limnology.
Einar Christian Leonard Naumann (1891 - 1934) studied in southern Sweden at the University of Lund. In 1917, he completed his Ph.D. in botany and zoology and advanced to docent in botany with studies on phytoplankton and sediment formation in some Swedish lakes. He conducted many diverse limnological studies, particularly in the Aneboda region, and established an Institute of Limnology at the University of Lund in 1929, when he assumed the chair of professor of limnology. Over a period of 23 years, Naumann produced 297 publications, including several books, such as the major work in 1931 Limnologische Terminologie (Björk 1988).
August Friedrich Thienemann (1882 - 1960) was trained in zoology in Innsbruck, Heidelberg, and Greifswald (Ph.D, 1905, on trichopteran pupae), and habilitated as docent at the University of Münster on the distribution of freshwater organisms (Rodhe 1975). In 1917, he was appointed director of the Hydrobiological Anstalt at Plön, then of the Kaiser-Wilhelm-Gesellschaft which later became the Max-Planck-Gesellschaft, and professor of hydrobiology at the University of Kiel. Thienemann directed the Max-Planck-Institut für Limnologie in Plön for 40 years. Over a 57-year period, he published 460 publications, which included several major monographs, particularly on the chironomids and regional comparative limnology (Thienemann 1959).
Thienemann and Naumann possessed enormously different personalities. Thienemann was cultured with a deeply rooted intellectual heritage in philosophy, particularly of Goethe, and the classics, was highly disciplined, balanced, and positive, and possessed an extraordinary working capacity. Naumann, in contrast, was impulsive, energetic, and unpredictable yet highly original and insightful. Despite these differences, their many years of independent limnological study before they met in the early 1920s gave them a commonality that quickly forged an intellectual and a personal friendship. Both scientists had been organizing biological and abiotic differences among lakes which resulted in a fusion of Thienemann's primarily regional (Subalpine-Baltic) lake types based on profundal fauna and oxygen distributions with the primarily trophic lake types of Naumann based on water chemistry and primary production of phytoplankton. The coupling of these properties with trophogenic and tropholytic zone relationships led to the oligo-, eu-, and dystrophic scheme still used today. Lake typology in the 1920s and 1930s was a catalyst for extensive regional limnological research that amalgamated various subdisciplines of lake studies into limnology (Elster 1958).