Invasive Species threatens Progress in Bay Cleanup

New Water Chesnut species  from USGS

 An invasive species of plant has recently arrived in our Potomac River Watershed. If we act soon we can still stop it. This is a new species of water chestnut is a relative of the well-known invasive species Eurasian water chestnut. The new plant has leaves with the same serrated pattern, but the underside of this new species is red. This species has pink flowers and the seed pods which form this time of year have two hooks on them.

Once water chestnut shows up in a water body, it spreads to cover large areas chocking out all other life. If allowed to flower and reproduce, can spread far and wide carried by Canadian geese, other wild life and the flow of the rivers and streams. This plant forms dense floating mats that cover the water surface, blocking sunlight and killing aquatic grasses and vegetation. Dr. Nancy Rybicki formerly of the U.S. Geological Survey and now teaching at George Mason University has been trying to alert owners of ponds and other water bodies that have been impacted.

Across Northern Virginia, this invasive water chestnut has spread to dozens of locations. It can still be stopped before it takes hold, but we need to act soon, before the water chestnut spreads from the small ponds it has infested and spreads to the Potomac River. Last year this new species of water chestnut was confined to 12 locations in Fairfax and Prince William counties. Now , it has been sited in 54 locations in 5 counties. It is spreading quickly.

It is spreading in stormwater ponds, farm ponds, golf water hazards, and ponds in parks. Once it flowers with a pink flower it produces its 2 horned fruit with barbs that attach to wildlife, but are sharp enough to puncture a shoe. The water chestnut is an aquatic annual herb. The fruit though horned and barbed is edible and has medicinal qualities and was probably brought to Northern Virginia intentionally. It sprouts from seeds in spring and the plants die off in winter after a hard frost, but the seeds can lie dormant for several years and be washed from a spill way down river.

from USGS

 
If this new water chestnut is allowed to establish itself in ponds around Virginia it could spread into the tidal waters, and we will face an epic control challenge that would both undo past decades of successful eradication of invasive species and undermine all our efforts under the Chesapeake Bay Total Maximum Daily Load (TMDL) and the resulting estuary water quality improvements- in restoration of the population of submersed aquatic vegetation. The Chesapeake Bay TMDL is a “pollution diet” mandated by the U.S.EPA to restore the health of the Bay and its local streams, creeks and rivers. The Chesapeake Bay TMDL—the largest such cleanup plan ever developed by the U.S. EPA—sets limits on nitrogen, phosphorus and sediment pollution necessary to meet water quality standards in the Bay and its tidal rivers.