When a series of massive algal blooms off Florida’s west coast ends in 2020, it will be associated with an estimated 2,000 tons of dead marine life around Tampa Bay. Human losses were also significant; There was also a double-digit increase in asthma cases in Sarasota and Pinellas counties and an estimated loss of nearly $1 billion in economic sectors ranging from tourism to fishing.
Earth-orbiting satellites have been used for decades to detect algal blooms from space, allowing observations to be made more frequently over larger areas than would be possible with direct water sampling. The most common observation method relies on the visible spectrum to measure ocean color. However, this approach was mostly limited to clear sky conditions.
A recent study Geophysical Research LettersThe research, conducted by scientists at NASA’s Jet Propulsion Laboratory in Southern California, showed how a space-based instrument called TROPOMI, or TROPOspheric Monitoring Instrument, can peer through thin clouds to reveal strong clues about Karenia brevis. (or K. brevis), the microscopic algae responsible for the 2020 bloom. TROPOMI’s advanced ability to “see” and measure subtle wavelengths of light could potentially help federal agencies and local communities better predict and manage harmful outbreaks. (TROPOMI flies on Europe’s Sentinel 5P spacecraft, launched in 2017.)
Scientists studied the West Florida Shelf, a section of continental crust that extends in an arc from the Panhandle to the Keys. K. brevis is carried to the coastline by strong winds and ocean currents from other parts of the Gulf of Mexico. Recent research has shown that West Florida, like many coastal communities, may be increasingly vulnerable to outbreaks because this algae thrives in nutrient-rich, warm conditions fueled by runoff, fertilizer and climate change.
Monitoring and forecasting systems for harmful algal blooms are available in many states and coastal areas, including the Gulf of Mexico and the Great Lakes. The National Oceanic and Atmospheric Administration (NOAA) works with academic, state, tribal, and local partners to develop and publish harmful algal bloom forecasts, similar to weather forecasts during seasons when blooms occur.
The K. brevis outbreak is particularly concerning because the algae produces a potent neurotoxin that, at high concentrations, can cause mass fish kills and poison marine life such as turtles, manatees and birds. The toxin can also cause respiratory disease in humans by inhalation, and can accumulate in shellfish, causing gastrointestinal illness in humans who consume it.
As the algae feed and grow through photosynthesis, K. brevis emits a faint red glow called solar fluorescence (red SIF), which can be detected by some satellite instruments, including TROPOMI, which is actually designed to measure air pollution.
Examining TROPOMI data obtained along the west Florida coast between 2018 and 2020, the team found that the device collected nearly twice as much information about the fluorescence emitted by algae as previous methods based on observed ocean color. TROPOMI’s advanced imaging capabilities, including four spectrometers that measure light in the ultraviolet to shortwave infrared range, allow it to penetrate thin cloud cover and obtain ocean surface measurements more frequently.
space advantage
The scientists said their findings demonstrate the value of using TROPOMI alone or in conjunction with other Earth observation instruments, such as NASA’s long-running MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Aqua and Terra satellites. MODIS measures ocean color and is now used by environmental managers in Florida and elsewhere to detect algae on clear days.
Another ocean color instrument, scheduled to launch in early 2024, will study the world’s marine ecosystems like never before. NASA’s PACE, or Plankton, Aerosol, Cloud, Ocean Ecosystem mission, will study phytoplankton and other ocean biology, atmospheric aerosols and clouds at a much longer wavelength than previous sensors. These observations will help predict the occurrence of harmful algae, as well as the boom-and-bust cycle of fishing and other factors affecting the commercial and recreational industries.
“For nearly 20 years, ocean color sensors have been the basis for satellite monitoring of harmful algal blooms,” said lead author Kelly Lewis, a NASA program scientist at JPL. “This application of the TROPOMI red SIF demonstrates how a combination of satellite technologies can strengthen early warning systems beyond clear skies.”
Satellite early warning has been proven to have real benefits. A recent case study found that early detection of cyanobacteria in Utah Lake led to significant savings in healthcare, lost work time, and other economic losses. A few days’ advance warning could lead to quicker action on the ground, including public notification and even beach closures. Source
Source: Port Altele
