Monitoring harmful algal blooms

16 March 2023


An Algal bloom is the rapid increase or accumulation in the population of algae in freshwater or marine water systems. Harmful Algal Blooms (HABs) are an issue of concern for water management worldwide as they pose a serious threat to public health, economy and biodiversity. HABS worldwide are increasing due to climate change and increased eutrophication. As reported in Science Direct, remote sensing has become an increasingly important tool for HAB detection and monitoring in large lakes. However, accurate HAB detection in small-medium waterbodies via satellite data remains a challenge.

To test the applicability of remote sensing for detecting HABs in small-medium waterbodies, three satellites (Planetscope, Sentinel-2 and Landsat-8) were used to understand how spatial resolution, the availability of spectral bands, and the waterbody size itself effect HAB detection skill. Landsat 8 and Sentinel 2 were the best satellites for HAB detection in small to medium waterbodies. The most critical attribute for detecting HABs were the available satellite bands, which determined the detection algorithms that can be used.

Algal bloom in a wetland after flooding. Photo: Tanya Doody 

Importantly, algorithm performance was mostly unrelated to waterbody size. However, there remain some barriers in using satellite data for HAB detection, including algae dynamics, macrophyte cover within the waterbody, weather effects, and the correction models for satellite data. Given these challenges, integrating regular sampling activities and remote sensing is recommended for monitoring and managing small-medium waterbodies.

Source of information: Remote sensing to detect harmful algal blooms in inland waterbodies – ScienceDirect

Harmful algal blooms and remote sensing