The DKP embayment, once rich with eelgrass, has experienced dramatic habitat loss over the past several decades. Scientists from Coastal Zone Management, the Division of Marine Fisheries, and the MassBays National Estuary Program sought a better way to understand the water quality changes driving this decline. Instead of fixed-location sampling, they aimed to collect continuous, embayment-wide data that reflected the full tidal cycle. Their goal was to use SeaTrac’s autonomous surface platform to track water quality across the entire system and evaluate its ability to navigate dynamic, shallow environments.

Base Platform and Equipment 

The mission used SeaTrac’s USV equipped with a YSI Series 600 sonde capable of measuring temperature, salinity, turbidity, dissolved oxygen, and chlorophyll in real time. The platform’s shallow-water capability allowed it to operate across the full DKP embayment—from deeper channels at low tide to mudflat-covered shallows at high tide.

Continuous Water Quality Monitoring

To capture complete tidal-cycle behavior, the mission route was planned to begin in deeper water after low tide and progress inland as the tide rose, ensuring access to the shallowest areas at high tide. As the tide receded, the USV shifted back toward deeper water. With roughly eight hours of run time and a total course of over 20 miles, the vehicle maintained steady survey speed and power throughout the mission.

Real-Time Data Transmission

Water quality data collected by the YSI sonde was logged onboard and transmitted wirelessly and simultaneously over RF, cellular, and Iridium links. Shore teams could monitor live readings, track progress, and address issues immediately—such as clearing a stuck sensor wiper through remote commands. All data was stored on dedicated servers for post-mission analysis.

The mission demonstrated the feasibility and value of mobile, continuous water quality monitoring within large, tide-driven embayments. The USV successfully navigated strong currents, shallow passages, and long survey routes while delivering consistent sensor performance. Data analysis revealed clear trends, including elevated chlorophyll and turbidity in shallower areas lacking eelgrass. In the image below, two maps show chlorophyll as captured in the first two voyages. The data showed consistently higher chlorophyll values in the shallower areas of the bays.  Higher values are darker.

Overall, this effort showcased the potential of unmanned surface vehicles to enhance coastal habitat research, support adaptive management, and deepen understanding of environmental changes affecting eelgrass ecosystems.