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Floating gardens seen as way to help reinvigorate Magothy River

Paul Spadaro walked along the edges of his backyard along the Magothy River and pointed to the shallow waters, clouded by a brown, murky mass. There was a time, the Severna Park resident said, that the waters were teeming with bay grasses that filtered the currents.

Then came development, and natural shoreline gave way to wooden bulkheads and fertilized lawns that seep nutrients into the river. That created murkiness, he said, blocking the sunlight the plants needed to grow.

To hear Spadaro tell the tale, Mother Nature would put greater Anne Arundel County in timeout if it were possible. The president of the Magothy River Association laments factors that he says have disrupted the river's natural balance, and he's spent more than a dozen years working to rectify the problem.

Over the past two years, the volunteer organization has teamed with Anne Arundel Community College to plant trays of "floating gardens" in the water. The plants are more formally known as submerged aquatic vegetation.

Like other vegetation, floating gardens provide food, remove carbon dioxide, oxygenate and filter pollutants from the water, Spadaro said.

Anne Marsh, an ecosystem ecologist who works with the project, said among the plants used for the floating garden are salt marsh aster, swamp milkweed, blue water iris, pickerelweed and duck corn.

The gardens are placed in bottomless flower pots that are mounted inside holes of buoyant boards made of plastic foam, then placed along the edges of the shoreline. Spadaro also has larger plants in bottomless flower pots mounted to mounds in the water.

Spadaro said the project is crucial, noting reports from the Virginia Institute of Marine Science that aquatic vegetation is virtually nonexistent in the Magothy River.

"We cannot have a healthy river system without" underwater grasses, said Spadaro. Such gardens, he said, will provide habitats for fish, add oxygen and remove nutrients from the water.

Stephen Ailstock, biology department chair at Anne Arundel Community College and director of the school's Environmental Center, said: "So much of our shoreline has been hardened with bulkhead or some type of structure. The college has been involved for many, many years with ecological restoration. It's a mutually beneficial arrangement.

"From our standpoint, it's a way of introducing some additional biodiversity into the creeks," Ailstock said.

"One of the real advantages of working with a group like the Magothy River Association is we can do a long-term study that factors in differences in seasons to identify which plants grow best in which areas you contemplate restoration," he said.

The college regularly collaborates with the Magothy River Association on restoration projects. Spadaro said that over the years, many people and organizations have tried some variation of floating vegetation in the Magothy. Those efforts met with varying success.

"We have tried many years to grow underwater grasses," Spadaro said. "They all failed because the [poor] water quality. And the water visibility is so murky that plants don't get the light they need."

That's why they hope floating plants will have a better fate. Ailstock said the community college has sent out volunteers to install floating gardens in four regions of the Magothy selected for their salinity levels. At the end of the year, the school records how well the plants grew and reproduced seeds.

"If we get a long-term average," Ailstock said, "we'll be able to say, 'Here's how well they did on a wet year; here's how well they did on a dry year; here's how well they did on an average year.' "

Ailstock said the plants have tissue that act as "gas pumps" introducing oxygen not only into the air but into the water via their roots. He said the college's Environmental Center is among many in the nation that are working to restore waters in which natural shorelines have been inundated with artificial boundaries.

There was a time, Spadaro said, when the local creeks were clear. Animals such as dark false mussels helped filter water and kept contaminants at bay.

"This time of year, the water was absolutely gin-clear; it was so gin-clear that if I dropped The Baltimore Sun off the end of the pier, you could read it. Those mussels working together, all that filtering power, kept the entire creek clean."

Spadaro said that bringing back plant and animal life will help restore clear waters to the Magothy, but the tide of development around the river must be stemmed as well.

"It's not that you will never see [clear waters]. You have to work on the other side of the equation," Spadaro said. "You can either put more oysters in, more mussels in, more plants in, but it's a lot easier to control and slow development to make that work."

jburris@baltsun.com

Copyright © 2014, The Baltimore Sun
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