An open early-warning system prototype for managing and studying algal blooms in Lake Lugano

Abstract. Lake Lugano is increasingly experiencing new processes and dynamics due to the combined effects of climate change and human activities. In recent years, abnormal phenomena of algal proliferation, known as Harmful Algal Blooms (HABs), have appeared on the lake. Particularly in 2023, after several critical events, public awareness of this issue has risen, as it can potentially impact socio-economic aspects related to the use of this locally important water resource. In this study, we aim to share the development process of a monitoring system designed to promptly inform about the increase in concentration levels, thereby initiating a protocol to support decision-makers. This system, based on open-source and cost-effective devices, is designed to gather information on these blooms, which pose potential toxicity risks to humans and animals. The system uses a Raspberry Pi connected to a Trilux fluorimeter, measuring algal pigments and transmitting data via NB-IoT. The data is processed using istSOS software, stored locally, and transmitted to a data warehouse. Alerts are set up based on phycocyanin (PC) levels, indicating cyanobacterial biomass and potential microcystin toxicity. The open-source nature of the system allows for easy replication and expansion, aiding decision-makers and researchers, and increasing citizen awareness.