By Brittney Miller, Student Reporter / UF Thompson Earth Systems Institute
Published June 22, 2020
Harmful algal blooms have grown to be an unfortunate Florida staple. Whether it’s a blue-green mass dominating a freshwater lake or a red tide creeping up a coastline, the sometimes-toxic phenomenon often makes headlines during the state’s warmer months.
Betty Staugler, a Florida Sea Grant agent, is part of a statewide troupe of scientists and officials who monitor these events. As a marine biologist, she said she normally calls herself a “boots-on-the-ground” person for the cause, one who works out in the field alongside blooms.
But within the past two years, she said she’s had to get used to another perspective, one from the stars: satellite imagery.
While the first artificial, or manmade, satellite was launched in 1957, Staugler first used the technology for her job as a Florida Sea Grant liaison to NOAA, or the National Oceanic and Atmospheric Administration.
By analyzing colors of the sea, NOAA’s satellites can detect algal blooms from states away, Staugler said.
Ocean color images from satellites help researchers track algae blooms, like this "high chlorophyll-a anomaly linked to harmful algae bloom" on Florida's west cost on July 26, 2018. (Credit: NOAA / NESDIS Center for Satellite Applications and Research)
All algae contain a photosynthetic pigment called chlorophyll that reflects green light. The ratio of reflected green light, which indicates algae, and blue light, which indicates normal water, is what the satellites are detecting, she said. The different emitted wavelengths indicate different types of algae as well.
These images, while they can’t thwart the growth of algae, give time for scientists and public health officials to alert the public.
“There’s really no preventing a red tide bloom,” Staugler said. “It’s really more communicating a bloom and making sure that we’re able to ramp up needed on-the-ground monitoring.”
More than 2,000 artificial satellites like these currently orbit Earth, and a larger hoard is expected to occupy the skies in the future. With their vantage point in our planet’s exosphere, or the outermost layer of the atmosphere, satellites can be the eyes for researchers on the ground. This tech is one facet of a developing field called “remote sensing.”
Remote sensing focuses on gathering data from a distance, whether that be inches or miles away. Instead of traveling to different locations and taking samples, researchers can now use optical machinery, like high-tech cameras, to glean information about Earth from afar.
This intersection between technology and the environment has a unique place in Florida’s research hub. Not only does it eliminate the need for invasive sampling, but it also cuts down on scientists’ labor and time by consolidating mounds of data across miles of land.
“That is the power of remote sensing,” said Aditya Singh, a University of Florida assistant professor in the field.
“The principle is making a physical observation on the ground and generalizing that across space so that you don’t have to make that measurement a million times over for every single map,” he said.
Where Technology and Earth Systems Intersect
Singh’s research and extension work revolve around customizing specific remote-sensing tools to investigate how the environment responds to stressors and disturbances.
Sensor options are limited by the available hardware that exists at the time, he said, creating a “one-size-fits-all” scenario for mass-producing the tech. But the raw data these sensors pick up can be specialized with different algorithms. Singh develops these formulas to translate the information in a useful way to each researcher.
Remote sensing tools can help researchers to better manage, analyze and protect Earth's systems. Examples of applications for each sphere are:
A drone takes flight directly in front of a structure destroyed by Hurricane Michael. This form of remote sensing can be used to assess hurricane damage, Singh said. (Courtesy of Aditya Singh and James Fletcher)
Distance Makes a Difference
Satellites are one of the most prevalent tools used in remote sensing — but are only one of a growing mass of tech in the field. In fact, satellites represent just one of three remote sensing layers used in environmental research: landscape, canopy and contact.
Each layer is organized by the sensor’s distance from its target. As the outermost layer, landscape remote sensing uses satellites to detect light from space. The next layer, canopy remote sensing, uses drones to capture light from a few hundred feet above a subject. Finally, contact remote sensing represents the closest distance in the field – only inches away from an object of interest.
Drone imagery can be used to assess hurricane damage to agricultural crops and forests, as seen in this photo. (Courtesy of Aditya Singh and James Fletcher)
This distance makes a difference. The further away an object is from the remote sensing instrument, the more susceptible the data is to contamination. For example, when sunlight bounces off of the Earth, it must travel miles up, through carbon dioxide and water vapor in the atmosphere, to get to a satellite.
So that means that as the scales of remote sensing get closer to the subjects on Earth, the more “pure that data is,” Singh said.
This radio monitoring device is an example of contact remote sensing. It’s located at an agricultural field at West Florida Research and Education Center. (Courtesy of UF/IFAS)
Satellites are used for widescale measurements due to their extended distance and thus expanded range. They’re a great fit for algae bloom monitoring, but Florida Sea Grant uses citizen science to verify that the data is correct, Staugler said.
This on-the-ground monitoring comes in the form of HABscope. The program applies citizen science and fieldwork to confirm the algae blooms spotted in satellite images. Manned with an iPod Touch and a microscope eyepiece, volunteers can collect water samples during a suspected red tide bloom. An app inspects each frame of a 30-second video, uses a specialized algorithm to see if algae cells are present and automatically reports the data.
“That information is what validates the satellite imagery that NOAA produces,” Staugler said.
While satellites have strengthened algal bloom tracking in Florida, Staugler also acknowledges their drawbacks. Weather patterns can block light from the satellites. And while the atmosphere eye is great for the state’s large coastlines, it’s harder when it comes to freshwater blooms in smaller bodies of water, she said. They’re too tiny for satellite detection from space.
The same goes for landcover detection in a state where different land segments aren’t big enough for satellite use. It’s rare to find a 10,000-acre farm in Florida, Singh said; instead, most crops or habitats are carved into smaller portions.
“Florida is special because we have almost 50 commodities that we grow here,” he said.
That’s why terrestrial researchers rely on drones that can fly from just above the tree line to as high as 400 feet. Florida has already made recent strides in utilizing this technology for different uses. For example, during this year’s legislative session, a bill was created that allows state programs to combat invasive pythons and wildfires using drones. This bill is currently being presented to Gov. Ron DeSantis – one of its final steps to becoming a law.
Singh kneels down to inspect the new heavy-lift "hyperspectral-thermal-LiDAR UAS," or drone, that his team built. (Courtesy of Aditya Singh and James Fletcher)
What Could We See in Florida’s Future?
As the field has developed over the years, Singh said remote sensing equipment prices have decreased, so accessibility to these tools has increased. And while the entire process – from flying the instrument to calibration to viewing the final data – has shortened in the past decade, he said there’s still room for improvement. If researchers can onboard algorithms onto the tools themselves, instead of downloading the collected data for analysis, it would eliminate time and equipment.
He said he also hopes that improved land health assessments are in the future for Florida’s remote sensing. With technology advancements, remote sensing can someday yield more specific data using what’s called “hyperspectrum remote sensing.” For example, Singh referenced using this technology to discover how much nitrogen is in leaves – just from a picture captured from a distance.
“If you can actually have a hyperspectral imaging system that you can calibrate and put on a drone, you can make maps of chemistries – not just what that crop is,” he said.
“The applications are endless.”