Maciej Gliwicz (1939–2024): A Giant in Freshwater Plankton Ecology

Maciej Gliwicz was born in Warsaw, Poland, in 1939, where he lived and worked until his death in June 2024. He studied biology at the Faculty of Biology and Earth Sciences at the University of Warsaw (UW). After graduating in 1962 with the defense of his Master's thesis on the zooplankton of the Tatra Mountains lakes, he began his Ph.D. studies at the Department of Hydrobiology of the UW. He was awarded a doctorate in 1969 (after defending his thesis “Food size selection and seasonal succession of filter feeding zooplankton in an eutrophic lake”; Gliwicz 1969), and became a Professor of natural sciences in 1991. He completed a postdoctoral internship at the Smithsonian Institute research station in Panama, in 1970. Later, he had numerous internships abroad (Fig. 1), collaborating with many scientists worldwide, and at the institutional level, mostly with the Max Planck Institute of Limnology in Plön, Germany. From the mid-1980s until 2009, he headed the Department of Hydrobiology at UW. Thanks to him, the Department has become an institution of international renown, well known in the global community of aquatic ecologists.

Maciej Gliwicz's impressive scientific output focused on the field of ecology, particularly the behavioral and evolutionary ecology of aquatic organisms and the ecology of pelagic communities. His interests included predator–prey relationships and trophic cascades in aquatic communities, specifically predatory fish–planktivorous fish–zooplankton–phytoplankton. He also worked on mechanisms of prey selection by predators, and mechanisms of defense against predation involving changes in morphology, life history, and behavior. In addition to basic research, he was an expert in biomanipulation methods to control the biomass and/or behavior of planktivores and, as a result of cascading trophic effects, to reduce the biomass of algae by planktonic herbivores. Methods of particular focus included those based on the use of predatory fish, as well as kairomones and other semiochemical compounds.

Professor Gliwicz's output of over 200 publications, cited over 10,000 times, places him at the forefront of contemporary ecologists and limnologists. On three occasions (including 2024) he has been ranked in the top 2% of the world's most influential scientists in terms of total output across all scientific disciplines (Scopus ranking).

Notably, in Gliwicz (1990), he described the relationship between the body size of filter-feeders and the threshold amount of food (i.e., the level at which the population growth rate is zero). This work shed new light on the mechanisms of ecological competition and provided the mechanistic explanation for the size-efficiency model of Brooks and Dodson (1965), which is fundamental to zooplankton ecology. He was the first to describe the interference of filamentous cyanobacteria with food acquisition (filtration) processes in large-bodied cladocerans and showed that this phenomenon, together with selective fish pressure, can lead to a remodeling of the composition of zooplankton communities in eutrophic lakes (Gliwicz 1977).

Following this, he discovered and for the first time described the “moon trap” phenomenon, explaining the coincidence in time of periodic collapses of zooplankton populations in African dam reservoirs on the Zambezi River with the lunar cycle (Gliwicz 1986a). The phenomenon involves a disruption of the typical cycle of diurnal light changes that initiate diurnal vertical migrations of plankton. During the day, zooplankton stay in the dark deep layers of water, hiding from planktivorous fish, while at night they move toward the surface to feed on phytoplankton, when they are invisible to fish. At the time of the full moon, the period of darkness between sunset and the appearance of the moon is followed by a period when the amount of light reaching the surface waters is sufficient for fish to detect the cladocerans, whose populations are then decimated.

Professor Gliwicz, together with several other limnologists from the Plankton Ecology Group, developed a model of the seasonal succession of lake plankton that has been adopted since the mid-1980s as a universal standard for describing the dynamics of phytoplankton and zooplankton populations in temperate zone lakes (the so-called PEG model). This work (Sommer et al. 1986) has received more than 2500 citations. A ground-breaking study on the extent of migratory behavior of planktonic animals in Tatra lakes as a function of the duration of co-occurrence with planktivorous fish, and thus on the course of co-evolution in the predator–prey system (Gliwicz 1986b), provided one of the first pieces of evidence that the ultimate (i.e., evolutionary) cause of the diel vertical migrations of aquatic organisms is the pressure of consumers from higher trophic levels.

Professor Gliwicz was a professional and dedicated academic teacher. He regarded the education of students as a mission, treated them seriously and respectfully, had high expectations of them, and was always perfectly prepared for his classes. His inspiring lectures attracted large audiences, and his field classes, which he organized by offering students the opportunity to carry out small research projects, were equally popular. Many of the participants in these courses still remember this kind of “apprenticeship” in science, which was the participation in Gliwicz's courses.

Among many other awards, Maciej Gliwicz was the recipient of the Foundation for Polish Science's Award (2001), the “Polish Nobel Prize,” in the field of natural and medical sciences. He was also the recipient of several very prestigious international awards: Smithsonian Institution Award for Academic Achievement (1970), Einar Nauman and August Thienemann Medal De limnologia optime merito awarded by the International Association of Theoretical and Applied Limnology SIL (1998), Ecology Institute Prize in Limnetic Ecology awarded by the International Ecology Institute (1997). With the latter award came an invitation to write a book in the Excellence in Ecology series, and in 2003 Professor Gliwicz published his opus magnum “Between hazards of starvation and risk of predation: the ecology of offshore animals” (Gliwicz 2003), an invaluable compendium of knowledge on freshwater plankton. He also received in 2012, together with Winfried Lampert, co-author of many of his publications and a friend, the Alfred C. Redfield Award from the Association for the Sciences of Limnology and Oceanography. The naming of a newly described genus of diatoms, Gliwichia, is a special honor for his contribution to plankton science.

Prof. Maciej Gliwicz performed his creative research and teaching projects with great panache and hype. He flourished in the role of project leader, infecting staff and students with enthusiasm and passion. He set the bar high, made enormous demands, and did not tolerate ignorance, laziness, omissions, or sloppiness. But he demanded the same of himself, and there was no doubt that we were dealing with a great personality in science and academia, an authority, and a master.

Being a hard worker, he could only slow down for his family, which was an equally important, essential foundation of his life. In essence, he represented the old conservative system of values, professional, family, and also patriotic. He managed to reconcile family life and extensive professional responsibilities with many other interests: exotic travels—overland and underwater, returns to the Tatra Mountains, the Polish seaside, and Masurian Lakeland; walks in Warsaw; sports—skiing, diving, and fast driving; playing bridge; cinema and books; and social gatherings, during which Maciek proved to be a great companion, a connoisseur of wine and whisky, and in the ancient times with his inseparable pipe….