Scientists Find Low Oxygen Off Local Shores

WILDWOOD — An area of low dissolved oxygen in the ocean exists from North Wildwood to Wildwood Crest.
It is one of four, low dissolved oxygen zones offshore of New Jersey with others off Barnegat Light, Little Egg Inlet and Sandy Hook, according to Michael J. Kennish, a research professor at the Institute of Marine and Coastal Sciences at Rutgers University.
He is part of the Coastal Ocean and Estuary Assessment project working with the state Department of Environmental Protection and federal Environmental Protection Agency assessing ecological conditions from the beaches to three miles out and coastal bay systems such as those behind Atlantic City and the Wildwoods.
The main cause of the low dissolved oxygen zone off the Wildwoods is upwelling from the coastal ocean, said Kennish. He said during summer, the wave patterns are primarily from the south while they come from the northwest in winter.
In the warmer periods of the year, late spring through summer winds are primarily from south to north along with the rotation of the earth pushes the water from the beaches outward to the offshore areas, he said.
“The deeper ocean water comes up underneath it to replace that water that is being shoved offshore and that water that comes in from the deeper parts off in the Continental Shelf is enriched in nitrogen and phosphorus from decay of plants…” said Kennish.
That water comes toward shore. He said the bottom of the ocean is a series of ridges and valleys not flat like a road. As you move south off the state, they are more ridges and valleys, so when water comes in from offshore it shoots into valley areas, which stimulates plants and algae in the ocean to grow.
“They become very abundant, they begin to die, they turn over very quickly,” said Kennish. When plant life dies, it settles to the bottom and bacteria will decompose the tissue.
“Bacteria are the major problem in the whole thing because they use up all the oxygen when they are decomposing the plants,” he said.
Kennish said dissolved oxygen in the ocean should not go below the area of 4 milligrams per liter. A condition of less than 2 milligrams per liter is referred to a hypoxia.
“Then you are in trouble because the animals can’t really function without having the oxygen they need and a times you can get a die off of animal populations,” he said, including fish.
In 1976, a major dissolved oxygen problem occurred covering much of the Continental Shelf off New Jersey causing a major die off of fish.
While much of low dissolved oxygen condition is natural, man may also be contributing to the problem by using fertilizer rich in phosphorus and nitrogen, which goes down storm drains into back bays and then into the ocean encouraging more plant growth in the ocean such as algae blooms, said Kennish.
He said back bays flush out very slowly to the ocean, which can allow pollutants to accumulate.
The ocean is relatively healthy but the bays and estuaries have problems, he said. Data is still being gathered, said Kennish, and evaluations may change.
He described back bays and estuaries along the state’s coast as impaired with problems such as algae blooms, loss of shellfish and jellyfish keeping swimmers out of the water.
Kennish said he has been tracking ocean temperatures that are getting warmer and are expected to continue that trend due to climate change. He said warmer water temperatures allow invasive species move in.
Surf clams in the ocean are moving northward while Winter Flounder is becoming less abundant, said Kennish.
“We have a lot more Atlantic Croaker which is an indicator of a warming condition because years ago they were not around and they are very abundant now,” he said.
He said the expectation is that New Jersey’s climate in 75 years will be like the current climate in South Carolina and Georgia.