The Water Chestnut

This ecosystem-altering plant is a prime example of a species which was brought to the Hudson estuary under innoccent circumstance. The water chestnut is a native of Eurasia, and was introduced in the United States as a decorative and ornamental plant, much like Japanese knotweed in terrestrial ecosystems. Its appearance in the US can be traced as far back as 1874 when a Harvard botany professor entered it in his catalogue. It is a rapidly reproducing and stifling plant, particularly abundant in freshwater sections of the Hudson. The water chestnut prefers slow moving water, which is abundant along the heavily jettied and developed Hudson shoreline. It experiences peak growth n the summer, from mid-July thru mid-September.
The primary cause for concern regarding the water chestnut is its penchant for significantly lowering the Dissolved Oxygen content of the waters in inhabits, which severely limits biodiversity and overall biological productivity. This is attributable to both its high reproductive rate and its actual structure. Large portions of the water chestnut's plant body is above the water surface, so the large populations end up forming canopies and blocking sunlight. The few submerged leaves aren't able to continue photosynthesis, which means oxygen production ceases and DO content of the particular water column declines. Water chestnut incursion on the tidal Hudson River is especially dangerous because during the ebb water underneath these enormous plant mats may become nearly anoxic, even more stressful to native species. It presents a hazard to recreational boaters due to the thickness of water chestnut beds and the potential for propellor jamming. Removal and prevention is time-consuming and difficulet, with work having to be done mostly by hand because of chemical ineffectiveness.