A global overview of the impacts of phytoplankton blooms on lake and reservoir ecosystem services

Abstract Phytoplankton blooms are an increasing concern for lake and reservoir management due to their rising frequency, intensity, and negative impacts on water quality and ecosystem functioning. Influenced by global change factors like climate change and intensified land use, especially urbanization and agriculture, these blooms are expected to become more common worldwide. Despite extensive research on bloom dynamics, mechanisms, and toxicity (notably of cyanobacteria), there is no comprehensive synthesis of their effects on ecosystem services. To address this, we conducted a systematic review of 48 studies globally documenting the impacts of phytoplankton blooms on key ecosystem services: fisheries, drinking water supply, and recreation. In fisheries, blooms cause significant losses primarily through fish mortality and habitat degradation, with toxins also reducing fish activity. Drinking water services experience serious disruptions, sometimes requiring costly treatment upgrades, while consumer complaints about taste and odor are common. Recreational activities suffer from swimming bans, decreased site attractiveness, and health risks. Toxic cyanobacterial blooms were the most frequently reported and damaging, though non-toxic algal blooms also cause notable problems. While some studies mention potential benefits of non-toxic blooms, these are limited and highly context-dependent. Our review also underscores the value of including grey literature alongside peer-reviewed studies to capture a fuller range of bloom impacts. Finally, we compiled cost estimates from various contexts, providing a benchmark for assessing the economic burden of phytoplankton blooms. The diversity and severity of impacts call for proactive, adaptive management strategies to mitigate disruptions and safeguard ecosystem services in lakes and reservoirs facing growing bloom pressures.