Presentation #1:

Context matters: Understanding the role of temperature in chemical control of quagga mussels in high conductivity waters by Michael Booth with the University of Cincinnati, Department of Biological Sciences

In December 2013, quagga mussels were found in Lake Piru, a water storage reservoir in southern California, leading to concerns regarding the spread of mussels downstream and potential impacts to endangered southern California Steelhead. Elevated water releases from the reservoir increased the flux of veligers downstream and led to mussel recruitment >15 km downstream of the reservoir. Periodic downstream colonization increases the likelihood for the infestation to impact agricultural and municipal water systems that receive water from the river and potentially impacts Steelhead habitat. Although there have been few successful efforts to eradicate mussels once detected due to a lack of cost-effective treatments, there was strong pressure to investigate full eradication of mussels in the lake. Two potentially cost-effective molluscicidal agents, potassium chloride (KCl, also called muriate of potash) and copper (formulated as Earthtec QZ®), have successfully treated infested waters, but have varying efficacy under different water quality and temperature conditions, and to date have only been applied in moderate conductivity waters (i.e., < 400 µS/cm). To understand the efficacy of these chemicals in a high conductivity system like Lake Piru (≈ 700–1,400 µS/cm) and under the range of water temperatures where a treatment might occur, we evaluated the dose-response of quagga mussels to KCl and Earthtec QZ® across a range of temperatures (10, 18, 22 °C) to determine appropriate doses and treatment duration resulting in 100% mortality. Our data indicate that treatments in cool temperatures (i.e., 10 °C) may be challenging for eradication efforts in high conductivity waters. However, both KCl (> 200 ppm) and copper (120 and 180 ppb) were consistently able to induce 100% mortality in quagga mussels in warmer temperatures (i.e., ≥ 18 °C) and thus have potential for field scale application in high conductivity waters. The results of this study indicate that field-scale application should strongly consider environmental conditions during the period of application when selecting dosages and treatment duration.

Presentation #1 Recording and Q&A:

Presentation #2:

Unraveling the nuances of dreissenid mussel control tool efficacy by Matthew Barbour and collaborators with the U.S. Geological Survey, Upper Midwest Environmental Science Center 

There are a limited number of control tools available for resource managers to address dreissenid mussel populations. Further, there is limited information on the effects of water chemistry and seasonality on the efficacy of available tools. This research aims to address these knowledge gaps to better inform resource managers decision-making processes and to facilitate efficacious control treatments. We examined the effects of water chemistry on carbon dioxide induced mortality in adult zebra mussels and identified key parameters correlated with shifts in efficacy. We also examined seasonal trends in adult zebra mussel susceptibility to copper to better identify temporal treatment opportunities for resource managers. Identifying the conditions under which dreissenid mussel control tools produce the desired target and nontarget effects could be important in developing a balanced ‘arsenal’ for resource managers to choose from given their management objectives.

Download Presentation #2 Slides Here!