2012 EPA Research Progress Report
Gliding Beneath the Surface
Low levels of dissolved oxygen in ocean environments have the potential to harm sea life and degrade the health of aquatic ecosystems. New Jersey’s coastal waters have long suffered from low oxygen conditions, putting the state in violation of water quality standards.
In order to improve understanding of the highly variable ocean processes that influence oxygen levels in New Jersey’s coastal zone, a collaborative team of researchers from New Jersey’s Department of Environmental Protection and Rutgers University developed a robotic vehicle to investigate beneath the ocean surface. Supported by EPA’s regional science programs, the team operated this autonomous underwater vehicle, named the Slocum Glider, and evaluated its ability to capture data about coastal water quality efficiently.
Dissolved oxygen levels have historically been measured based on infrequent sampling, providing imprecise results. In contrast, the Glider takes rapid-fire readings of dissolved oxygen, salinity and temperature at various depths, resulting in a much more comprehensive database for dissolved oxygen. The Glider also goes where ships and scientists cannot safely go; it sampled beneath Hurricane Irene, one of the few times these types of data were captured during such a powerful storm.
The Glider was re-launched on July 10, 2012 to collect water quality readings along more than 185 miles of the New Jersey coastline. This experiment monitored coastal conditions during the peak of summer, when a transitional, mixed layer of water separates warmer surface waters from colder layers below. Under certain conditions, this layering of the water column can lead to poor water quality and be harmful to humans and aquatic life.
Information gathered by the Slocum Glider is informing New Jersey’s upcoming re-evaluation of impaired coastal waters. Use of this glider technology has already allowed EPA’s regional office in New York to divest from its previous practice of monitoring dissolved oxygen by helicopter, which was a costly approach with limited results.