Aquatic Invasive Species

The northern snakehead has become a widespread invader in the United States. Due to this species’ ability to survive and thrive in many different environments, control efforts for this species must implemented. Poison is one of the various methods being explored. In laboratory testing, several different concentrations proved lethal to the snakehead . Lazur et. al determined that the smallest lethal dose was 0.075mg/L of rotenone, a commonly used aquatic poison. Such a dose killed all test subjects within 1 hour of administration, and proved incredibly effective in a pond setting in Crofton, MD as 8 adult and 834 juvenile snakeheads were recovered. These results demonstrate a susceptibility of this species to known control methods. However, all other aquatic fauna in the affected region succumbed to the poison as well. Additionally, the affected area remained toxic for at least one week after treatment. It is suggested that this method only be utilized in clearly defined and isolated areas.

(North American Journal of Fisheries Management 2006; 26: 628-630)

Wetlands 20, 280-299 (2000)

The spread of Phragmites australis, common reed, throughout Gulf and Atlantic Coast marshes has been virtually unstopped since its introduction in the late 1930’s. Because of Phragmites’ rapid spread, in areas such as the Chesapeake Bay, its current distribution and colonization rate is unknown. Dan Rice and colleagues at the University of Maryland used a geographic information system (GIS) to gain greater perspective into Phragmites distribution and colonization in three tidal freshwater and four brackish marshes in the upper Chesapeake Bay. Survey results indicated the presence of Phragmites at all seven sites. Using geometric growth formulas, rates of increase for each Phragmites stand were calculated. Older, more established stands have reached equilibrium while newer stands have increasing rates of growth. Rice et. al.’s results seem to suggest that there are limitations to the spread of Phragmites despite its prolific nature.