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Plant islands revive wetlands

Murky stormwater ponds, ugly waste-water lagoons and threatened wetlands might soon look and feel better.

Murky stormwater ponds, ugly waste-water lagoons and threatened wetlands might soon look and feel better.

The tonic is in the form of small floating islands filled with beneficial plants that help improve water quality, curtail erosion and benefit wildlife.

In southeastern Virginia, these grant-funded islands have been planted and are being studied and evaluated at the College of William and Mary in Williamsburg, Virginia Institute of Marine Science at Gloucester Point, Virginia Zoo in Norfolk and Elizabeth River sites.

The islands are typically recycled 20-centimetredeep plastic mats, each about three metres square, with planting holes and anchors for security. The buoyant mats act as a rooting platform for plants and provide a surface growth area for biofilms that attract beneficial microbial activity, scientists say.

Plants placed in the holes establish a hanging network of roots and rhizomes that help filter pollutants.

The islands can function in any water depth, and are usually planted with native species - cardinal flower, irises, sedges and grasses - that can also be enjoyed in home gardens.

"Since we began the study in late April this year, we have noted other functions of the floating wetlands," says W&M professor Randy Chambers.

"Soon after planting the wetland, we noticed snakes, frogs and turtles using the wetland as a haul-out location. Herons have been attracted to and land on the floating islands to feed. [And] hummingbirds frequent the cardinal flowers."

W&M student Katherine Thomas, in charge of monitoring water quality in the pond, thinks the whole continent can benefit from the project in Virginia. Stormwater ponds anywhere could have better esthetics and water quality.