Systematic and automated aerial surveys of rocky intertidal communities using low-cost unmanned aircraft systems (UAS)Novel Approaches

João Nunes¹, Fernando P. Lima¹, Rita da Silva¹, Rocio Nieto-Vilela¹, Rui Seabra¹

¹CIBIO/BIOPOLIS, University of Porto, Portugal

Understanding the impacts of climate change requires effective biodiversity assessments and insights into community structure and function. However, intertidal communities pose unique challenges due to their high habitat variability, complexity, and temporal dynamics, requiring frequent and comprehensive surveys. Traditional methods are often time-consuming, costly, and limited in spatial extent or taxonomic resolution. To address these limitations, professional-grade Unmanned Aircraft Systems (UAS), or drones, are increasingly utilized in ecological research, offering efficient, high-resolution surveys over large areas. Nevertheless, their adoption faces obstacles such as weather dependency, regulatory constraints, repeatability issues, and, importantly, equipment costs. Lightweight and low-cost drones have the potential to overcome most of these challenges, but their long-term effectiveness under real fieldwork conditions has been rarely tested.
This study aimed to test, optimize, and operationalize protocols for systematic aerial surveys using low-cost, consumer-grade drones (< €750) to monitor intertidal habitats. We compared aerial biodiversity assessments with traditional ground-level photoquadrat surveys. Using affordable equipment, our protocol enabled automated, repeatable surveys over a year, covering areas averaging 80 m² with a resolution of 0.145 cm/pixel. Results demonstrate that low-cost drones can effectively establish baselines and track monthly changes in species distribution and abundance (e.g., Sargassum muticum and Fucus sp.) on rocky shores. Additionally, data captured ecologically significant events, such as grazing patterns and bleaching episodes that could otherwise go unnoticed. This approach highlights the value of drones as a time- and cost-effective tool for intertidal biodiversity monitoring.