In search of a trade-off: phytoplankton – planktonic crustaceans – fish relationships (in memory of Z. M. Gliwicz, 21.02.1939–2.06.2024)

The results of the main studies of Z. M. Gliwicz are reviewed, highlighting his views on the evolution, biology and ecology of aquatic organisms. He was an outstanding hydrobiologist, and his scientific contributions to the development of hydrobiology were mainly related to aquatic ecology, including the prediction of the outcomes of competition between cladoceran species, vertical and horizontal migrations of zooplankton and fish, feeding behavior of fish, predator-prey relationships, interactions between adjacent trophic levels in ecosystems, and issues of evolutionary ecology. The results of Z. M. Gliwicz’s studies are analyzed in the context of the development of aquatic ecology in the late 20th to early 21st centuries.