Above image: PlanetScope image of Sargassum along the Miami beach shoreline taken May, 12, 2019. © 2019, Planet Labs PBC. All Rights Reserved.
In recent years, Sargassum, a large brown macroalgae, has been reported to beach along coastal shorelines in large quantities. As these piles of beached seaweed begin to decompose, they can cause negative impacts for both wildlife and human health. Due to climatic variability and human activities, there has been an increase in Sargassum blooms in an oceanic area called the Great Atlantic Sargassum Belt. As these blooms reach the Atlantic shore in areas like Miami, Florida and Cancun, Mexico, they begin to rot, releasing hydrogen sulfide gas and ammonia which present risks to human health and impede beach access for nesting sea turtles. In good news, Sargassum holds a chlorophyll pigment that reflects infrared light, making it easy to detect with satellite imagery, but with coarse spatial resolution and low-revisit frequency, it can be challenging for local management to monitor when, where, and how much of this algae will arrive on the beach. With this in mind, researchers from the University of Southern Florida and Planet teamed up to study how Planet’s Dove satellites, with their daily imaging capabilities and 3 meter resolution, offer enough data to support a deep learning computer model to predict such events. Their model results revealed two major Sargassum indudation events on Miami beach and Cancun beach that were consistent with local reports. “With the availability of 3-m resolution PlanetScope/Dove and PlanetScope/SuperDove data around the globe, the findings suggest that it is possible to monitor dynamic inundation events of not only Sargassum but also other macroalgae in many other regions,” said the authors.
The full study can be found in the IEEE Geoscience and Remote Sensing Letters.