To Decline, or Not to Decline?

Emily Chang

Professor Sandra Cooke

Writing 20

24 March 2010

To Decline, or Not to Decline?

J. Aquat. Plant Manage 38: 105-111 (2000)

A study by Raymond M. Newman and David D. Biesboer (2000), both of the University of Minnesota, investigates whether there are possible relationships between the population of the milfoil weevil Euhrychiopsis lecontei and that of Eurasian watermilfoil (Myriophyllum spicatum). Control of the aquatic milfoil plant is important because it has harmed aquatic diversity, hindered human boating and recreation, and withstood both mechanical and chemical control methods. The researchers examined the Eurasian watermilfoil colonies and abiotic conditions, such as alkalinity, of the man-made Cenaiko Lake from 1996 to 1998. Samples of milfoil plants were collected from the lake and tested for carbohydrate analysis and weevil density determination after the plants were dried. The results of the study showed that declines in milfoil populations caused increases in the biomass of other plant species. Increases or decreases in weevil populations  paralleled those in watermilfoil. The researchers conclude that larger-scale experiments involving the watermilfoil, weevil, and their environment will help support these findings.

One Response to “To Decline, or Not to Decline?”

  1.   dkl9 Says:

    Invasive species are a huge detriment to the aquatic environment that they have invaded. Consistent control is an important trait for any agent of control and the milfoil weevil seems to fit this description. Like the predator-prey relationship, the milfoil weevil population increases and decreases with the population of watermilfoil. Instead of trying to sustain the population, the population of the weevil is based on the watermilfoil and nothing else, making it specific and not a detriment to other plant species. In periods where there is a low population of watermilfoil, other plants get an opportunity to grow, allowing restoration of an ecosystem over time. Biocontrol in this case has shown to be the best measure in the case of watermilfoil because of consistent control and because it allows the invaded ecosystem an opportunity to recover.