October 18, 2023
Pilot project uses drone technology to monitor harmful algal blooms in freshwater lakes
The effects of climate change are leading to an explosive surge in harmful algal blooms, jeopardizing drinking water supplies and threatening human health. occur when algae grow exponentially, potentially producing toxins that can poison fish, mammals and birds 鈥� as well as cause human illness or even death in extreme incidents. Thus, investigation is required to better mitigate their harmful effects.
In spring 2023, an interdisciplinary team of 91探花 researchers were awarded a Tier 1 Population Health Initiative pilot grant to better understand harmful algal blooms in freshwater lakes. Led by , a second-year master鈥檚 student in the 91探花Department of Environmental & Occupational Health Sciences (DEOHS), this project aims to integrate a into the monitoring of HABs in Echo Lake, a body of water located in Shoreline, Washington. 鈥淭he main goals of this project are to assess the feasibility of using drones for freshwater lake monitoring, record the challenges encountered and help guide future drone applications in this field,鈥� explained Teresi. Other 91探花investigators include (DEOHS), (DEOHS) and Gordon Holtgrieve (School of Aquatic and Fishery Sciences).
This pilot project will measure the presence of HABs using chlorophyll concentrations as a proxy for the algal growth of the lake. 鈥淐hlorophyll is the photosynthetic pigment in all algae and cyanobacteria. It’s what takes energy from the sun and converts it into chemical energy,鈥� explained Teresi. The more chlorophyll detected in the lake, the greater the likelihood a HAB will occur.
A visual assessment of algal growth of the lake from above may provide more information than the same assessment from the shoreline or boat. 鈥淏asically, we’ll go out and fly the drone around the lake,鈥� described Teresi. 鈥淭he drone is going to be taking hundreds of photos as it goes and, essentially, all those images are entered into photo processing software that will stitch them together into one large image of the lake.鈥�
鈥淭his image will then be processed using Geographic Information System (GIS) software, which will analyze and assign a value to every pixel on a scale of how 鈥榞reen鈥� it is,鈥� said Teresi. In theory, the greener the pixel, the greater the amount of chlorophyll is in that section of water.
To double-check that these images are correctly approximating the chlorophyll concentration, water samples will be collected from different areas of the lake and tested in the lab. 鈥淚f there’s a moderate or strong correlation between these two values, then we can confidently say that a drone can be useful for estimating the amount of chlorophyll in a lake,鈥� explained Teresi.
Incorporating drones as a supplemental monitoring tool to estimate chlorophyll levels in an entire lake can help water managers better prepare for HABs and, therefore, better protect people. 鈥淚f we have aerial images telling us the lake is becoming progressively greener, it could become an algal bloom that turns harmful and produces toxins,鈥� emphasized Teresi. 鈥淲e can then communicate this risk to the public and take more of a proactive rather than reactive approach.鈥� This information is critical during a time when climate change continues to exacerbate the conditions that allow harmful algal blooms to thrive in crucial freshwater resources.
Ultimately, incorporating aerial vehicles into environmental monitoring is still an emerging field. 鈥淚t’s definitely been a work in progress,鈥� said Teresi. 鈥淭here’s been a lot of hiccups along the way and some changes. But we’re still pretty excited about what we鈥檒l find with this work.鈥�