January 10, 2024 — Two Rutgers University scientists recently discussed the possible implications of their findings last summer of low dissolved oxygen and pH off the New Jersey coast, which concurred with numerous reported mortalities of fish, lobsters and crabs.
Grace Saba and Josh Kohut work within Rutgers’s Center for Ocean Observing Leadership, in the Department of Marine and Coastal Sciences. The center, as the university notes, maintains the world’s most advanced coastal ocean observatory, with platforms consisting of satellite imagery, a radar network for surface current mapping and waves, and a fleet of long-duration autonomous underwater vehicles, called gliders, equipped with physical, chemical and biological sensors.
Saba, an associate professor, and Kohut, a professor, employed gliders to map ocean water quality measures along the coast, surface to bottom, from late April to late September 2023. As they explained, “From August through September, much of the bottom water sampled from Sandy Hook south to Tuckerton, and from nearshore to deeper depths, exhibited dissolved oxygen concentrations less than 5 mg/liter and pH values less than 7.75.
“Coast-wide, hypoxic levels of dissolved oxygen (concentrations of less than 3 mg/liter) were observed at shallower, more inshore locations. In addition to low pH measured in bottom waters, which is indicative of ocean acidification, aragonite saturation state – a relevant metric for biological impacts of ocean acidification – was calculated to be less than 1 in several locations. Normal, more optimal levels in seawater typically include dissolved oxygen concentrations of more than 7 mg/liter, pH of 8.1, and aragonite saturation states of more than 3.”