Scientists at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) and the Cooperative Institute for Marine and Atmospheric Sciences (CIMAS) deployed a new series of Sofar “Spotter” buoys at four of the seven Mission: Iconic Reefs within the Florida Keys National Marine Sanctuary (FKNMS) identified as essential sites for restoration.
The Sofar buoy at the surface measures wave energy, wind speed, sea surface temperature, and pressure. Below the surface, integrated sensors measure pH and seafloor temperature in near-real time – actively monitoring ocean acidification on crucial reefs.
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The global impacts of ocean acidification are well-known. But a decade-long study led by scientists at AOML revealed last year that there are spatial gradients in how OA progresses across the Florida Keys, and some sites in the Upper Keys may act as refugia able to mitigate a decrease in pH – potentially due to the higher abundance of seagrass beds and other benthic communities.
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With these Sofar buoys and a newly-developed online application, scientists with AOML’s Coral Program are now actively seeing how conditions fluctuate and monitoring instrument functionality in real-time at four of the seven Mission: Iconic Reefs: Carysfort, Horseshoe, Cheeca Rocks and Sombrero Reefs in real-time.
However, the true advantage that set the Sofar “Spotter” buoy for the team came with their ability to customly integrate an advanced sensor monitoring changes in pH across these reefs.
While probes and pH electrodes, are often strapped to buoys and other deployable instrumentation in the marine environment. These sensors may not be of sufficient quality to monitor the gradual progression of OA and over time they degrade, leading to drifting data that can compromise a monitoring program Scientists with AOML’s Coral Program have taken a different approach.
The Sofar Spotter buoy floats at the surface monitoring ocean conditions with a protected data cable running to the seabed. The bristlemouth development kit (center) receives pH and temperature data from the SAMI-pH sensor (bottom left).
Integrating a Sami-pH logger at the base of each buoy, the team uses a colorometric system where seawater enters the device – comprised of micro pumps, injector valves and reactor cells – and undergoes a chemical reaction when exposed to reagents.
This reaction changes the water’s color. A change that the Sami-pH measures and quantifies as a pH reading, it is sent via the cable to the buoy and over satellite or cellular to the Coral Program’s online application, providing a high-resolution pH measurement of a reef in near-real time.
With the Sami-pH’s ability to perform this process consistently for up to ~6 months without maintenance, the Coral Program can more accurately monitor whether coral reefs are exposed to more acidic (i.e. lower pH) waters.
As hurricanes, tropical storms and severe weather brush the Florida Keys, scientists at AOML will also be able to see how these storms influence coral reefs as they hit – and whether they provide relief when water temperatures are peaking or exacerbate the impacts of other stressors.
Ultimately, deploying these novel integrated systems is the beginning of an easily – scalable solution to monitor marine environments and fill gaps in ocean acidification research by providing better data collection both spatially and temporally.
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Chris Malanuk, Atlantic Oceanographic & Meteorological Laboratory, 12 March 2025. Full article.
