BROKEN LAGOON: Nutrient-Rich Muck Lurks On Indian River Lagoon Bottom
In the Indian River Lagoon muck is the substance representing everything dumped into the lagoon during the past half-century.
John Trefry holds up a hand smeared with muck, black as tar.
“It’s very fine-grained. It really does look like black mayonnaise. It smells like rotten eggs. I guess you mix the mayonnaise with your rotten eggs there. And it just is not a very hospitable-looking material.”
Trefry of the Florida Institute of Technology has been studying the Indian River Lagoon’s muck for 30 years. He and his research team are docked off of Palm Bay in Turkey Creek, where the team is examining water quality. A scientist leans over the boat’s side and plunges a long PVC pipe into the water, measuring the creek’s depth and the muck’s.
Here the muck is four feet deep. Trefry says it is the color of the decomposing materials making it up.
“So picture a football field 1,000 yards high full of this stuff.”
That’s how much muck is estimated to be on the bottom of the Indian River Lagoon. For more than a half-century a fast-growing population has been laying sod and trimming lawns as the soil, clippings and other debris have been washing into the lagoon, accumulating and decomposing on the bottom.
“It only covers about 10 to 15 percent of the lagoon. It can be anywhere from just an inch deep to five feet, 10 feet deep, and where it is nothing lives there. And it is easily resuspended, and it makes the water turbid, and it blocks light which has an effect on the seagrasses.”
Trefry says especially worrisome is that the muck represents a growing reservoir of nitrogen and phosphorous, nutrients at the heart of the Indian River Lagoon’s water quality problems. The nutrients feed the algal blooms that have killed off dolphins, pelicans, manatees and this spring triggered the worst fish kill in modern history.
That’s why a new effort is underway to remove the lagoon’s muck as Trefry and other researchers work to understand the stuff and its impacts.
A drone rises from the shore of Turkey Creek. Jon Shenker of the Florida Institute of Technology is studying the muck’s effects on fish. His team uses a drone to gather aerial views of the creek’s larger fish. Farther down the beach the team catches smaller fish using a net. The team gathers data on species and size.
“One of the main impacts is that it covers up a lot of the habitat where these fishes normally would live, but in the muck there’s hardly any food for small fishes. So they would be restricted to an area where the food is available.”
Back on the water Trefry and his team motor near a dredge that is one of two removing muck from the Indian River Lagoon. A third will start this summer. A large pipe marked by orange buoys snakes from the dredge more than a mile through the lagoon, carrying the muck to an onshore retention site. Eventually the muck can be used in landfills or as a soil additive.
The team anchors and begins gathering water samples. A machine pushes water through a tube into plastic bottles like medicine through an IV.
The PVC pipe is plunged into the water to measure depth. Here the dredge has removed more than eight feet of muck.
“It’s a combination of keeping things from running off the land and dredging out what’s already here to make it new. It’s not going to work with just one or the other. We can’t just remove the muck, and we can’t just stop what’s coming in. We gotta do both.”
Trefry says it’s too soon to tell what impact the dredging already is having on the lagoon, but he believes the restoration will improve the entire system. He estimates it would take five to 10 years to remove all of the muck from the Indian River Lagoon.