Cyanobacteria in the Anthropocene: Synanthropism forged in an era of global change

The Anthropocene has driven a transformative era where human activities exert unprecedented influence on Earth's biosphere. Consequently, synanthropic organisms, adept at thriving in human-modified environments, have emerged. While well studied in terrestrial ecosystems, the presence and ecological importance of synanthropic species in aquatic ecosystems, specifically among cyanobacteria, are less understood. Cyanobacteria blooms, notorious for their detrimental effects on ecosystems and human health, are increasing in frequency and intensity globally. In this perspective, we explore the evidence supporting this rise of cyanobacteria blooms, emphasizing the roles of human-induced eutrophication and climate change on select cyanobacteria genera. Cyanobacteria are not a monolith, with certain genera showing an observable increase within anthropogenically modified environments. We propose the establishment of a new sub-branch of phycology that explicitly investigates the ecology and physiology of synanthropic cyanobacteria. Understanding the intricate interactions between synanthropic species and human populations is imperative for managing human-altered ecosystems and conserving freshwater resources, particularly in the face of increasing global water insecurity. PRACTITIONER POINTS: The rise in cyanobacteria blooms is driven by a small subset of human-adapted genera-synanthropic cyanobacteria. Research is needed to characterize synanthropic cyanobacteria, which will aid in developing tailored management approaches. A paradigm shift from domesticating to "rewilding" landscapes and modifying behaviors to facilitate cohabitation are solutions to reducing risks.