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Artificial reefs revive dead canals

November 6, 2018
By JESSE MEADOWS ( , Fort Myers Beach Bulletin, Fort Myers Beach Observer

In the midst of the worst water quality crisis Southwest Florida has seen in years, David Wolff has devised his own plan to clean it up: artificial reefs.

Since he started his non-profit, Ocean Habitats, in 2016, he has installed "mini-reefs" beneath residential docks in more than 60 cities.

Now, local governments are taking notice.

Article Photos

Since David Wolff started Ocean Habitats in 2016, he has installed “mini-reefs” beneath residential docks in more than 60 cities.


On Oct. 15, the Town of Fort Myers Beach voted to allocate $10,000 for a pilot project that would deploy 50 mini-reefs in canals around the island.

On a Thursday afternoon in Cape Coral, Wolff unloaded stacks of polypropylene, PVC pipe, and fishing rope with his 17-year-old son, David. They set to work stacking sheets of corrugated black plastic on columns of PVC pipe, and threading ropes through each level.

They're designed to be flexible, he explains, so they can withstand the flow of natural water currents and the shake of storms when they're installed underneath docks.

Plastic is the only material he could find that wouldn't break down in the water - his mini-reefs can last for 500 years.

"In theory, the plastic is going to last longer than your dock is. You're going to have to put them over to the side and replace the dock and put them back," he says.

It might sound strange to use plastic to help the environment, but some animals that live off these reefs can live for decades, he explains, and the goal is to leave them untouched.

"We have units we got off the bottom in Sanibel that had been there from back in our research days, when I worked for the Marina Habitat Foundation. They were down there for 17 years," he said.

Wolff began this work as a Marine Biology undergrad at USF, specifically looking for ways to clean water for the aquaculture industry.

It took his team a total of 106 attempts before they finally found a design that was affordable, durable, and able to clean 30,000 gallons of water per day at peak efficiency.

Unfortunately, the Foundation went under, and everyone who worked on the project moved on with their lives. Wolff got married and went into real estate.

"I was in business for 15 years, working 100 hours a week to make money," he said, "So I thought back to the stuff I'd done in my life, and when I thought about working on this research when I was in college, I realized that I probably worked just as many hours on this stuff as what I was doing in real estate, but I loved every day."

He placed some calls to his old colleagues to see if anything had been done with their undergrad work, but the project was dead in the water. Wolff decided it was time to trade in his suits for board shorts.

"Obviously the environment is way more in people's minds now than it was in the late '90s. Back then, people said, everything's fine, you're nuts, you're a treehugger, and now everyone is screaming because they've got Jell-O behind their house, they can't catch any fish, and everything smells," he said. "So I just decided to go for it."

Here's how the mini-reef works: the structure, made of fiberglass, PVC pipe, corrugated polypropylene, and crab-trap floats, provides a home for filter feeders like oysters and mussels that eat phytoplankton (such as Karenia brevis, the cause of red tide).

These small organisms attract bigger fish, crabs, and even dolphins. Floating out of the way underneath docks, they act as a replacement for the mangroves that were removed to build the city's canals.

"Canal systems are biological deserts. They're not very productive at all. They're awesome for boats, they do a great job of getting rainwater out of the city... but they just fill up with pollution over time. The bottom of all these canals is full of everybody's fuel leaks over the last 70 years, whatever has blown in and rotted, and that's the kind of stuff that gets stirred up by hurricanes," he said.

Wolff and his son work while they talk, constructing nine mini-reefs in the course of an hour. Their client, also an academic with a particular interest in marine biology, has bought as many reefs as will fit under his dock.

"We've had some people who put a couple in and tell all their neighbors about it, then the guy across the street buys 10 instead of two, so the guy calls back and he buys nine so he can have one more. It's like keeping up with the Joneses," he laughs. "But it's good, because it's that much more work that's getting done."

This model of competitive environmentalism has proven more effective for Wolff than government action.

Until recently, the project has been largely consumer-driven. He estimates that 95 percent of his sales have been to private residents who say poor water quality has affected their property value.

The mini-reefs are a tax-deductible solution that don't require any upkeep or special permits.

The Gainesville-based non-profit installed its first reef under a residential dock on Marco Island in July of 2016. In the spring of 2017, the city voted to install 25 of its own reefs. The island now boasts 548.

There are over 200 currently floating in Lee County's waters, with 142 in Cape Coral alone.

Installation is simple. Wolff's son David puts on swim shoes and hops into the canal. Wolff drops several reefs to him at a time, and he sinks them into the water, then secures them to the dock's posts.

A recent study of water quality around Wolff's mini-reefs, conducted by students from Florida Southwestern State College, found that dissolved oxygen levels were higher, phosphate levels were 35-40% lower, and water was considerably less murky in their immediate vicinity.

Wolff hopes to install mini-reefs around Fort Myers Beach as soon as possible, before the water gets too cold for the habitats to grow efficiently.

"Fort Myers Beach is sitting right at the end of every decision made upstream," he says.

The town has yet to decide where to install its mini-reefs, but Wolff says the ideal canal would be small enough to show measurable change in water quality, but have enough docks to house 50 units.

"We've got it narrowed down to three: the canal on Madera, the canal on Avenida Pescadora, and the canal on Ibis," said Rae Burns, the town's Environmental and Stormwater technician.

These options will be brought to the Marine Resources Task Force at its next meeting, scheduled for Nov. 14.

If you'd like to install a mini-reef of your own, one unit costs $250, includes delivery and installation, and can grow 300 fish per year. Go to for more information.



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