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Biologists question viability of St. Petersburg Pier's Underwater Garden plans

Published Mar. 18, 2012

ST. PETERSBURG — The centerpiece of the winning design for the city's new $50 million Pier, dubbed the Lens, is a soothing oval of green amid the soaring white concrete walls. Within the oval lies what designers have called an Underwater Garden, to be filled with oysters, sea grass, fish and manatees.

No sea grass now grows beneath the Pier, and the water is murky at best. Yet California landscape architect Tom Leader told the jury that selected the Lens: "We can recreate the diversity that existed once within this enclosure."

While the Underwater Garden plan has been embraced by city officials, it has been met with skepticism by biologists.

"Whoever wrote this doesn't know a thing about sea grass," said Margaret "Penny" Hall, the top sea grass expert at the state's Fish and Wildlife Research Institute in St. Petersburg.

The Underwater Garden isn't essential to the Lens' structural plans. Still, it's a signature feature that has captivated community leaders.

"I thought that was one of the outstanding features of the project. It certainly is a major feature and really struck a chord with me,'' said Will Michaels, chairman of the Pier Advisory Task Force's design committee. If it fails, "you'd be losing a very important part of the design."

Task force vice chairman Ed Montanari said the Underwater Garden struck him as "one of the main attractions to walk out there.''

Michaels, a former president of the Council of Neighborhood Associations, said that when CONA members reviewed the Lens design, they learned of concerns about the Underwater Garden's feasibility among St. Petersburg's large community of marine science experts — which includes federal and state biologists as well as university professors and researchers.

But the Los Angeles-based designer of the Lens, Michael Maltzan Architecture, contended in an email to the Times that the Underwater Garden "is based on sound principles of estuary restoration and species diversification that have been applied and proven effective throughout Tampa Bay."

The plan, as envisioned by the Tom Leader Studio, calls for keeping the pilings that now support the Pier and using them as the framework for an artificial reef that would be adjacent to the area where boats would dock.

To create the Underwater Garden, the plan says, oysters in wire mesh bags would be put into trays attached to the pilings. The oysters would filter and clarify the murky water. Four kinds of sea grass would be planted — Johnson's, manatee, widgeon and turtle — in a tilted circle the plan calls a sea meadow ring.

"A series of planted trays placed at varying depths in the water will provide the right habitat for many species of sea grass," the plan says. "These trays can be arranged in a ring around the inner bowl and will attract manatees looking to graze."

As the oysters clarify the water, allowing more sunlight to penetrate, sea grass growing near the Pier will fill in bare spots and "attract larger sea life as well like manatees and sea turtles." The plan also calls for installing underwater lights that would "reveal marine life and become a natural aquarium."

To Hall, the biggest problem is the idea of planting Johnson's sea grass. It's the rarest sea grass in Florida, growing only in a small area on the Atlantic coast. The federal government lists it as a threatened species.

Another questionable part of the plan is the idea of growing sea grass in trays, rather than on the bay bottom, which at 10 feet in that spot is too deep for sea grass to sprout naturally.

"You certainly can grow sea grasses that way," said Mark Fonseca, a top sea grass expert with the National Oceanic and Atmospheric Administration. "We grow sea grass in captivity that way."

However, Fonseca said, he doesn't know of anyone who has ever tried growing sea grass that way outside of a laboratory.

He also questioned the notion of growing new sea grass so close to where boats would be zipping in and out, explaining, "If there's a lot of waves, that could be a little bit of a problem."

There's a bigger problem in that area than the lack of sea grass. According to Gregg Brooks, a marine science professor at Eckerd College, a recent survey by his students found "fine-grain, organic-rich mud deposits" up to 3 feet deep, most likely due to human development along the shoreline.

That type of sediment is often contaminated by pollutants such as heavy metals that can be toxic to marine life, he said, and the only way to clear it out is to dredge the bottom.

The Times emailed the designers of the Lens 17 questions about the Underwater Garden project. The questions included "Where will you be getting your Johnson's grass from?" and "How will you keep waves from nearby boats from affecting the growth in the Underwater Garden?"

The reply from project director Tim Williams to six questions — including the ones about Johnson's grass and boats — was, "To be determined during the design process." That was also the answer about whether they still plan to build the tilted sea meadow ring.

Williams said the team came up with the idea "from looking at different aspects that have been done before.''

But when the Times asked if there were any projects anywhere that had tried the techniques being proposed for growing sea grass, Williams was unable to cite a single one. "Ultimately all projects are unique, and the Lens is no different," he replied.

He acknowledged the design team had not done a survey of what's under the Pier now. He said the city and the designers are working with the U.S. Army Corps of Engineers "to identify what surveys are required and when they should be done."

He said the Underwater Garden section of the plan had been prepared based on input from marine ecologist James Culter of the Mote Marine Laboratory in Sarasota, an expert in plants and animals that grow on the bottom of bays and oceans. Culter referred all questions back to the designers.

The Maltzan team estimates the Underwater Garden could be created for $879,565, though the budget does allow for contingencies. That does not include the cost of constructing full-scale mock-ups to determine whether the idea would work — or asking for help from local scientists who are raising questions.

Now that the city has accepted the concept of the design, Williams said, "we plan on reaching out to the scientific community and pulling them into the conversation. Once we talk with the scientific community, we're pretty confident we are going to come to a consensus about what can be put out there ."

Craig Pittman can be reached at Waveney Ann Moore can be reached at or (727) 892-2283.