Blooms of cyanobacteria are triggered by an influx of nutrients – for example, through wastewater discharge or run-off high in fertilizer or manure. The potential of using cyanobacteria to assess water quality in aquatic environments has been discussed for many years.

Today, thanks to geo-tagged spectral data from satellite and aerial imaging, it’s possible to gather such information on sources that are putting ecosystems at risk. The study was led by Valeria Costantino of the University of Naples Federico II and Massimiliano Lega of the University of Naples Parthenope.

As a test bed, the team selected four areas all subject to anthropogenic pressure, but differing by location and salinity. Measurements focused on the Agnena river, Patria and Lucrino lakes, and the Caracciolo waterfront.

First the team obtained satellite data across spectral bands matched to the bloom’s green colour-signature, which provided coordinates for areas high in cyanobacteria. Next, the group deployed aerial imaging, again using cameras sensitive to the pigment but offering much higher spatial detail.

The flight plan of the aircraft was programmed for a specific altitude to guarantee a resolution of 10–15 cm per pixel. These images helped the researchers identify points for the final stage – in situ testing – by providing accurate locations for sampling, negative control and reference values.

The study draws attention to features such as man-made channels, pipelines and unmapped springs. And the team believes that its results confirm the assumption that cyanobacteria blooms can serve as useful bioindicators of degraded water quality in coastal ecosystems. However, the work doesn’t stop there.

"The real challenge is to make politicians and governments aware of possible problems [affecting water quality] and to find solutions to them," Costantino told environmentalresearchweb. "To stop the cyanobacterial blooms from spreading you have to remove the cause of the pollution."

The group’s mapping method could help to put everyone in the picture. As Costantino adds, progress in the use of unmanned aerial vehicles (UAVs)/drones together with further improvements in imaging hardware represent a great opportunity for environmental monitoring.

The team published the results in Environmental Research Letters (ERL).

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