Once the initial detection has been completed, a long-term monitoring program can be designed, developed, and implemented. Clearly identifying and defining the objectives of the program will help to determine the type of monitoring and control programs that will be most effective within your site or facility. Basic knowledge of the zebra mussel's life cycle and minimum water chemistry requirements will help to determine which level of monitoring will be most appropriate for your site or facility.
Monitoring generally focuses on three parts of the life cycle: the planktonic veliger, initial settlement or colonization, and final adult colonization. A variety of sampling gear is used to detect veligers, settlement, and adult colonization. These include plankton nets, filamentous substrates, solid substrates, and visual observation. Each type of sampling gear can be used to produce data that are either qualitative (presence or absence data) or quantitative (e.g., veligers/liter or mussels/mē), depending on what type of information is wanted. A description of each of the sampling activities and gear, the advantages and disadvantages of each, and some recommendations for deployment and sample processing can be found in Monitoring Techniques.
Results obtained from the monitoring program are critical for any long-term control strategy. Not only the effectiveness of the current control program can be determined, but control programs can be adjusted to enhance infestation reduction measures in the future. It may become apparent that maintenance and inspection schedules need to be changed or that the control measures implemented are most effective when deployed at various times or at specific locations throughout the facility. Therefore, for long-term cost-effectiveness, it is prudent to keep accurate monitoring data. Information on implementing a record-keeping system can be found in the Importance of Maintaining Long-Term Records of Monitoring Datasection. In a long-term chemical control program, for example, such practices will likely result in reduced control costs, with the amount of chemical used being optimized.
When formulating the needs of a site, examine the two basic types of monitoring strategies, Mainstream Monitoring and Sidestream Monitoring, to match user needs to the data that a monitoring program is capable of providing.