Babylon had its hanging gardens; one day the Charles River basin could have floating gardens

The Charles River Conservancy hopes to install a "floating wetlands" at North Point Park next spring to test whether the reintroduction of wetlands to the Charles River basin could shield enough microscopic animals to eat and so control the bacteria that now sometimes turn that stretch of river into a hazard to both man and beast.

Working with Northeastern PhD candidate Max Rome and the Penelope Taylor Studio, the group would install a roughly 700-square-foot floating platform to plant a variety of wetlands plants to determine whether that could be used to shield zooplankton from the fish that have been increasingly drawn to the Charles as its water quality improves.

The floating wetland will be planted with over 20 native wetland species. Plants like rose mallow, cardinal flower, and milkweed will be arranged to create a unique floating garden, an attraction for human and non-human visitors. Throughout our study, we will monitor the plants to understand which species succeed in this novel environment.

If it works, the zooplankton in turn could begin to devour the cyanobacteria, also known as blue-green algae, that now can explode in numbers, creating toxic blooms that can kill dogs that swim in the river and make people sick.

The small platform itself would have no noticeable affect on the overall basin, the group says, but proof of its success could be the impetus to install far more of the platforms - or to plant more permanent wetlands vegetation in what has long been more of a lake than a river, one that, despite clean-up efforts over recent decades, remains chock full of the phosphorus that encourages the growth of the bacteria.