Rutgers, NJDEP, and Coast Guard Coordinate to Recover Glider Monitoring Water Quality

Today, in a coordinated effort between Rutgers, New Jersey Department of Environmental Protection (NJDEP), and the U.S. Coast Guard, an underwater glider was recovered off the coast of New Jersey (NJ). The Rutgers/NJDEP glider was recovered using the Coast Guard Cutter Finback, led by Officer in Charge, BMCS M.D. Buckman. The U.S. Coast Guard is evaluating what autonomous underwater vehicles (AUVs; Slocum gliders, Wave Glider, etc.) will be of use to them in their operations and assessing whether their current assets (cutters, patrol boats, helicopters) can accommodate these AUVs (see article here: http://www.uscg.mil/acquisition/).

This glider just finished its third and final mission for this summer/fall season where it has been mapping dissolved oxygen (DO) along the NJ coast as part of a joint project between Rutgers and NJDEP.

A glider is pulled into a Coast Guard vessel. Photo by Travis Miles.
Coordinated glider recovery2
Ken Hayek (NJDEP), Nicole Couto (Rutgers), and two members of the U.S. Coast Guard pose with the glider. Photo by Travis Miles.

Reduced or depleted DO in seawater significantly affects coastal ecosystems and causes large disruptions to local food webs via mass mortalities of fish and commercially important shellfish such as surfclams, quahogs, and scallops. Low DO events are frequent in the summer along the NJ shelf and are associated with large phytoplankton blooms. Thus, the Environmental Protection Agency (EPA) and New Jersey Department of Environmental Protection (NJDEP) have provided financial support to Josh Kohut at Rutgers University to monitor these low DO events using Autonomous Underwater Vehicles (AUVs) called gliders. Every summer since 2011 they conduct glider deployments focused on sampling the physics, phytoplankton, and DO characteristics of the nearshore coastal ocean. Each year, there are three missions that begin in Sandy Hook and end off Cape May. The real-time data is posted on the web and used by NJDEP to identify poor water quality regions. The real-time data also allows for adaptive, shipboard sampling to make more detailed observations during low DO events.

Josh with glider
Josh Kohut (Rutgers) deploys a glider to monitor water quality off the NJ coast in July. Photo by Jeff Mart.

The recent annual monitoring from this project has demonstrated that low dissolved oxygen (DO) zones along the NJ shelf are variable in time and space. DO concentrations below 5.0 mg L-1 have been documented every summer, and DO concentrations less than 2.0 mg L-1, which is below the limit of juvenile and adult shellfish and finfish survival, have been frequently detected during recent summers.

josh do glider data
Cross-sections of dissolved oxygen (DO) concentration from a glider deployment completed in August 2012. The color bar indicates DO concentrations in mg/L.

The timing of Kohut’s glider deployments is well aligned with the annual Gliderpalooza events. The data Kohut collects during this time are available for analysis by other Gliderpalooza groups focused on the modeling of the Cold Pool, a distinctive mass of cold (< 10o C) bottom water, as well as the ecological questions related to fish migration and habitat. When asked about the benefits of Gliderpalooza, Kohut responded favorably. “I think Gliderpalooza is an excellent opportunity to collaborate across the region and extend the application of the NJDEP deployments to address much larger questions. The deployments will happen regardless of the coordination, but with it I gain a much better understanding of what is happening beyond the footprint of these missions. I also get the opportunity to work with a larger group and share the interpretation and deployment strategy of the missions.”