Tamayo, M., C.E. Grue, and K. Hamel, 2000. The Relationship between Water Quality, Watermilfoil Frequency, and Weevil Distribution in the State of Washington, University of Washington.

Reprinted with permission from Journal of Aquatic Plant Management (2000) 38: 112-116

During the summer of 1997, we surveyed 50 waterbodies in Washington State to determine the distribution of the aquatic weevil Euhrychiopsis lecontei Dietz. We collected data on water quality and the frequency of occurrence of water-milfoil species within selected watermilfoil beds to compare the waterbodies and determine if they were related to the distribution of E. lecontei. We found E. lecontei in 14 waterbodies, most of which were in eastern Washington. Only one lake with weevils was located in western Washington. Weevils were associated with both Eurasian (Myriophyllum spicatum L.) and northern watermilfoil (M. sibiricum K). Waterbodies with E. lecontei had significantly higher (P < 0.05) pH (8.7 +/- 0.2) (mean +/- 2SE), specific conductance (0.3 +/- 0.08 mS cm(-1)) and total alkalinity (132.4 +/- 30.8 mg CaCO3 L-1). We also found that weevil presence was related to surface water temperature and waterbody location (chi (2)(2) = 24.3, P less than or equal to 0.001) and of all the models tested, this model provided the best fit (Hosmer-Lemeshow goodness-of-fit chi (8)(2) = 4.0, P = 0.9). Our results suggest that in Washington in waterbodies with pH greater than or equal to8.2 and specific conductance greater than or equal to0.2 mS cm(-1). Furthermore, weevil distribution appears to be correlated with waterbody location (eastern versus western Washington) and surface water temperature.

Entire Paper
Contact: Mariana Tamayo, School of Fisheries, University of Washington, Box 355020, Seattle, WA 98195-5020, USA
Key Words: Eurasian_watermilfoil, Population_dynamics, Basic_biology
Product Type: Research, Basic_biology
User Type: Resource Management