Control Methods
A suite of chemical and non-chemical options exists for controlling invasive mussels; some treatments are appropriate solely for hydropower facilities and water delivery systems, in which fish are not present and the water can be treated before being released into a sewage system. Other treatments, which may have lower toxicity to fish and living organisms, are more appropriate for open water situations. Many treatments may not be appropriate, or feasible, for response in open-water systems. Information in this section of the toolkit includes the treatment options most likely to be used in open-water systems.
Regardless of the type of treatment implement, bioassays should be used to determine the effectiveness of each chemical or mechanical treatment. If adult dreissenid mussels are present in a water body, mussel mortality would be assessed via in-situ cage bioassays (Lund et al. 2017). Four cages of ∼50–100 mussels per cage would be placed within the treatment area. Cages would be constructed of plastic canvas mesh sheets (1–2 mm openings), anchored to the lake bottom. If the water body is stratified (having distinct epilimnion, metalimnion, and hypolimnion), additional bioassays representative of the different layers may be appropriate. Live, gaping, and dead mussels would be recorded daily until all mussels are dead or until no additional mussels die over three consecutive days.
​Bioassays may need to be conducted with proxy species because some jurisdictions may not allow the use of adult dreissenids, particularly if the initial detection was a veliger detection, and no presence of adult mussels was detected.​
​
Combinations of treatments may be used, and retreatments may be necessary. Treatment areas would be isolated to maximize dreissenid mussel exposure time, incorporate variables, such as temperature variations (which affects efficacy of potash), and provide for re-treatment, if needed. The first demonstrated use of benthic mats to successfully eradicate a dreissenid mussel population occurred in Lake Waco, TX after zebra mussels were discovered in 2014. Placement of benthic mats for 5 months, followed by monitoring over five years, resulted in a declaration of "eradication" by 2021 (Conry et al. 2024).
Chemical Methods
The use of chemicals requires knowledge of permitting, labeling, and chemical-specific application regulations (BOR 2015).
​
-
Muriate of Potash—used as a biocide; requires a Section 18 of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Pesticide Emergency Exemption from the US Environmental Protection Agency (USEPA) because this product is not registered for control of dreissenids.
-
EarthTec QZ™—used as a biocide (should be considered foruse only in waters without salmonid and trout species).
-
Zequanox®—a biopesticide derived from a strain of naturally occurring bacteria, Pseudomonas fluorescens.
-
Natrix®—used as a biocide; is a molluscicide in still or flowing aquatic sites (should be considered for use only in water bodies with non-salmonid/trout species).
-
Rhodomine dye—used to evaluate water flow and containment effectiveness (not used as a biocide).
Mechanical and Other Methods
-
Intense Ultraviolet-B and Ultraviolet-C Radiation
-
Water level management
-
Physical removal
-
Benthic mats
Table 1. Summary of application rates and contact time for dreissenid chemical treatments.
[1] Carcinogenic substances have the potential to cause cancer. Genotoxic substances have the potential to damage genetic information within a cell, causing mutations, which may lead to cancer. Ectoxic substances have the potential to place biological, chemical, or physical stressors on an ecosystem.
[2] In a study in the Netherlands, the overall density of dreissenids decreased, but six months after the water level was increased, the mussel density slightly increased. Within 18 months, the mussel density had recovered to pre-drawdown levels.
Information on boat/vessel quarantine protocols:
Uniform Minimum Protocols and Standards for Watercraft Inspection and Decontamination Programs for Dreissenid Mussels in the Western United States (2021) (pages 26-27)
​