INDIAN RIVER COUNTY — There is some good news about the lagoon, for a change, according to the latest pollution mapping done by Ocean Research and Conservation Association, commonly known as ORCA.
When ORCA researcher Chloe Lloyd took sediment samples from 60 sites in the lagoon near the Oslo Road Boat ramp and The Moorings last fall, they turned out to have far less nitrogen than ORCA Chief Scientist Edie Widder expected.
Prior sampling to the north had found dangerous levels of the ecologically toxic nutrient, which feeds algae blooms that lead to fish kills and seagrass die-offs, but the color-coded map that shows the most recent test results is mainly bright blue, which indicates low levels of nitrogen in most of the square-mile test area.
“We thought the levels would be higher,” says Widder.
She believes the natural shoreline along the mainland side of the lagoon is largely responsible for the good condition of the waterway. Natural wetlands and mangroves filter water and consume nutrients.
The seawall-lined canals and channels of the Moorings development itself are an ominous red on the map, showing high levels of nitrogen, and Widder believes the contamination is due in part to grass clippings – which are loaded with nitrogen from fertilizer – getting into the water when lawns are mowed.
“People who use a lawn service need to make sure the landscapers are using best practices and not over-fertilizing and blowing grass clippings into the streets and culverts that lead to the lagoon,” said Robin Dannahower, ORCA vice president of marketing and public relations.
On a positive note, nitrogen levels are low along the shoreline near The Moorings golf course. The golf course is Audubon-certified, meaning it uses natural resources in a sustainable manner.
“Apparently it’s possible to have a golf course there and it can look like that,” said Widder, referring to the blue color of the map near the course. “We can find hope in living with nature without destroying it and ourselves.”
Good news about the lagoon has been rare in recent years.
In 2012-13 several unprecedented nutrient-fed algae blooms caused the loss of more than half the seagrass in the lagoon, devastating the ecology of the waterway, which has not fully recovered. There have been dolphin and manatee die-offs since the big blooms and just a few months ago another algae bloom caused a massive fish kill in the northern lagoon that left millions of dead fish floating in the murky water.
Widder says the fish kill in Brevard County was especially troubling, not just because of its extent, but because it killed all species of fish, raising the specter of a dead zone in what was until recently the most ecologically diverse estuary in the United States.
Direct fertilizer runoff, road runoff and seepage from septic systems are other main sources of nitrogen, phosphorous and other toxic chemicals in the lagoon.
