Scientists Set Record with Self-Driving Robots
Deploying multiple vehicles simultaneously allowed the research team to continuously sample the biologically important deep chlorophyll maximum within a moving eddy field, setting a new record for duration in this type of mission. Open-ocean eddies are swirling masses of water that move slowly across the Pacific Ocean, and can have large effects on ocean microbes.
The AUV’s were deployed for the first time in Hawaiian waters, and remained in the water collecting data for nearly 100 hours before recovery. Timing is important as it allows for the science team to map the eddy’s structure in 3D while sampling over the course of several daily cycles. This temporal sampling is key, since like people, microbial plankton are believed to synchronize their activities in repetitive daily cycles. The LRAUVs could simultaneously map and sample the oceanographic eddy features in much greater spatial and temporal than would have been possible using other platforms.
Eddies have been difficult to study because of their natural variability, which means their impact on ocean biology, specifically the microbial communities trapped inside, is not well understood. This cruise focused on a cyclonic eddy, rotating counterclockwise, which results in an uplift of the water column that brings nutrients and organisms from greater depths closer to the surface, and sunlight. This is thought to enhance phytoplankton’s primary productivity and activity in microbial communities that typically reside in deeper, darker waters.
The expedition’s Principal Investigators Drs. Edward DeLong and David Karl, oceanography professors in UH Mānoa’s School of Ocean and Earth Science and Technology (SOEST) have been studying these microbes for decades. “These new underwater drones will greatly extend our reach to study remote areas, and allow us to sample and study oceanographic events and features, even when ships are not available,” said DeLong. “Looking at a day in the life of all these ocean microbes and autonomously tracking them to see what happens on a day-to-day basis is something that’s never been possible before”.