| Popis: |
Valve response and filtration rates of adult zebra mussels, Dreissena polymorpha, exposed to elevated levels of K+ were assessed to determine the efficacy of using K+ in conjunction with a biocide to control mussel infestations. Mussels, 10 to 15 mm total shell length, were exposed to K+ at concentrations ranging from ambient to 2.00 mmol/L for 3, 6, 12, and 24 h at temperatures of 12 and 22°C. After exposure, each mussel was tested for valve response by tactile stimulation and filtration rate was estimated by clearance of latex microspheres from test solutions during a 30 minute period. Responsiveness was not affected in mussels exposed to ″ 1.00 mmol/L K+ for up to 24 h. Valve closure, however, was inhibited in ≥ 92% of the mussels after exposure to 2.00 mmol/L K+ for ≥ 12 h. Thus, the use of K+ to inhibit valve closure in mussels during the application of some biocides may increase contact time between the biocide and the soft tissues of mussels. Filtration rates of mussels, however, decreased as the K+ concentration increased from 0.50 to 2.00 mmol/L. At the K+ concentration that inhibited valve closure (2.00 mmol/L), filtration rates of mussels were > 90% lower than mussels at ambient K+ levels suggesting less biocide may be drawn in the mantle cavity to act on susceptible tissues. Therefore, use of K+ to prevent valve closure during the application of a biocide may not enhance the efficacy of the biocide due to the inhibitory effects of K+ on filtration. Furthermore, facilities treated with K+ at levels necessary to prevent valve closure may threaten native bivalve populations. |
