Field Sampling Methods

Monitored lakes were selected to represent ecologic and recreational diversity. Lake sites include those with little apparent human impact,  high quality ecological conditions, and no known apparent AIS introductions to sites where human activities were obviously causing changes in the lakes and where ecological conditions are likely to be impaired. This selection was done by visually observing each site and selecting those that would provide an overall mix of conditions. Lakes vary in size, depth, surrounding land ownership, and boat accessibility.

Volunteers will be asked to collect data on a bi-weekly basis at a mid-lake deep site. Examples of data sheets for volunteers' use can be found in Appendix A and are adapted from the USEPA 2007 Volunteer lake monitoring methods manual.

General Monitoring Procedures

Hour of Day for Observations

Taking Water Temperature

Visual and Tactile Observations

Educational Materials Provided to Volunteer Monitors
Volunteers will be provided educational materials related to the prevention and early detection of zebra and quagga mussels. Volunteers will be given an educational resources web site list pertaining to zebra and quagga mussel information. The Pacific States Marine Fisheries Commissions “Don’t Move a Mussel” DVD will be provided to all volunteers. This DVD explains the problems that zebra and quagga mussels have caused and precautions that need to be taken to prevent their movement and spread. Volunteers will also be given a “Zap the Zebra” brochure from the 100th Meridian Initiative program.

The educational materials provided are the result of literature search of current educational information on zebra and quagga mussel prevention and detection.

Parameters to be Monitored:

Secchi Disc Transparency
Developed in 1865 for a Vatican-financed Mediterranean oceanographic expedition by Professor P.A. Secchi, the Secchi disc has since become a standard piece of equipment for lake scientists. It is a weighted circular disc twenty centimeters (about eight inches) in diameter with four alternating black and white sections painted on the surface (USEPA 2007).

The disc is attached to a measured line that is marked off either in meters, if using metric units, or feet if using English units. The Secchi disc is used to measure how deep a person can see into the water. It is lowered into the lake by the measured line until the observer loses sight of it. The disc is then raised until it reappears. The depth of the water where the disc vanishes and reappears is the Secchi disc reading. In extremely clear lakes, disc readings greater than ten meters can be measured. On the other hand, lakes which are nutrient rich and affected by large amounts of algal growth, suspended sediments, or poor visibility often have readings of less than one-half meter. In shallow lakes, it is impossible to get a Secchi disc reading because the disc hits the bottom before vanishing from sight. The true Secchi disc reading is greater than the depth of the lake in that particular location and would negate a true Secchi disc reading (USEPA 2007).

Figure 1. Description of a Secchi Disc. Source: Maine Volunteer Lake Monitoring Program.

Dissolved Oxygen

Another critical indicator of lake and pond conditions in which zebra and quagga mussels can survive is the concentration of oxygen dissolved in the water. In addition to the amount of dissolved oxygen (DO), other indicators include temperature, the concentration of algae and other plants in the water body, and the amount of nutrients and organic matter that flow into the water body from the watershed. Oxygen is produced through plant metabolism (photosynthesis), and is consumed during respiration and decomposition (USEPA 2007). Oxygen in lake water is also influenced by wind and wave action through weather events and the exposure of surface water to atmospheric sources.

An adequate supply of dissolved oxygen in lake water is essential to fish and other aquatic life forms. DO is also a sensitive indicator of change in water quality, and of the ability of a water body to support aquatic life. The loss, over time, of DO in the deep areas of a lake, especially during summer months, may indicate that the ecosystem is stressed and changing. The NWMTLVMN staff member will collect the DO with the help of the volunteer.

Water Temperature

Volunteers will also be asked to take water temperatures, using a basic weighted thermometer attached to a string, 1.5 feet below water surface.

Calcium Water Sampling

By sampling for calcium levels in lakes, risk prioritization for introductions of zebra and quagga mussels (such as high, medium or low) can be provided based on calcium levels. Since the discovery of zebra mussels in the Great Lakes in 1988, several studies have found regions or water bodies with greater calcium concentrations as a key factor affecting the mussels’ potential distribution (Mellina & Rasmussen 1994). Calcium carbonate is the main component for construction of the zebra mussels’ bivalve shell and, in high concentrations, creates the ideal environment to support zebra mussel infestation (Mackie 1993). Cohen & Weinstein (2001) found that zebra mussels thrive in waterways with calcium thresholds 20 mg/L or greater. Volunteers will be asked to take a onetime calcium water sample which will be collected and mailed to a lab for analysis.

Visual and Tactile Search for Zebra and Quagga Mussels

Volunteers will also be provided basic information about AIS species, including where to look for them and how to identify zebra and quagga mussels. Any sightings of AIS are to be reported directly to FWP or WLI. After lake sampling, it is important to thoroughly wash your boat and dry equipment to help prevent the spread of AIS (DEQ 2009).

Visual and tactile (by touch with your hands) methods are adapted from the Pennsylvania Sea Grant and California Sea Grant Zebra Quagga Mussel monitoring protocols.

Since one of the identified means of movement of zebra and quagga mussels is recreational boating, boat ramps and public access areas along waterways are the most likely places for mussels to inhabit. Inland lakes, ponds, and reservoirs are very important areas to monitor.

Quagga and zebra mussels prefer dark, shaded areas. Volunteer AIS monitors will be asked to pick monitoring locations near boat ramps, docks, marinas, and under bridges.
Polarized sunglasses can help to reduce glare and improve vision into the water.  All hard and soft substrates should be inspected. Zebra and quagga mussels do not like direct sunlight so are found in water deeper than 6-12" (15 to 30 cm); also objects should be searched which are located in dark, shaded areas. Volunteers should also be sure to check underneath objects like driftwood and the dark crevices between rocks. Using the tactile approach (use of your hands) the volunteer monitor should gently run their fingers over smooth surfaces checking for mussels too tiny to see easily. Newly settled mussels feel like the grit on sandpaper. Larger mussels will feel coarser, like a small pebble or sunflower seed. Mussels can attach to a wide variety of objects such as:

Data sheets for recording visual observation data can be located in Appendix A for early detection monitoring of quagga and zebra mussels.

Veliger Sampling

Along with visual monitoring for AIS, plankton tow nets are used to sample for early life stages of AIS species like zebra mussel veliger (U.S. Army Corp of Engineers, ZMIS). Volunteers will be trained at an advanced monitoring training session on how to take plankton samples. Plankton samples will be collected from each lake in late July/early August when water temperatures are adequate for the free swinging larvae to be captured. The volunteers will be provided a plankton tow net sixty-three micron mesh size and a 2" inch (50 mm) diameter opening, ~29 feet (9 meters) of marked and weighted rope, squirt bottle and thermometer.

All equipment is disinfected and inspected before each outing to prevent transfer of AIS to other lakes. Tow net sample locations are chosen offshore from public boat launches and/or the deepest location within the lake. Water current and wind direction should be noted because veligers are passive swimmers and will collect on the windward side of lakes. There are two methods of sampling depending on water depth. The preferred sampling depth is greater than 29 feet (9 meters). Lakes with areas of depths that reach 9 meters or more will use the Vertical Haul method (OFAH). If there are no areas within the lake that are of this depth then a Horizontal Haul method will be used.

Vertical haul nets are slowly lowered to 23 feet (7 meters). Once the appropriate depth is reached, the net is slowly pulled up approx. one foot (0.3 meters) per second using a hand over hand motion. The net is lifted so the cod (closed) end is completely out of the water allowing the water to drain and plankton are collected in the cod end.

Horizontal Haul methods are adapted from the (OFAH) veliger sampling protocols. Nets are sunk to ~three m (nine feet) or a sufficient distance that the net does not get caught in the boat propeller. The net is towed behind the boat at a slow speed for approximately ~23 feet (7 meters). Once the boat is stopped, the net is quickly removed from the water allowing the water to drain and plankton to collect in the cod end.

Once the water has been drained from the net, it is rinsed by dipping the net into the water and lifting it up and down steadily. This allows any remaining microorganisms and plankton on the net to be rinsed into the cod end. It is important not to lower the mouth of the net below the water’s surface as this will allow microorganisms to escape. A spray bottle is used to clear the net of any remaining microorganisms that still remain after rinsing. After sample collection the cod end is removed and contents of cod end are poured into the sample bottle. Alcohol is added to the sample bottle (two parts alcohol: one part sample) to preserve the sample. The disinfection and inspection process is repeated to ensure that any AIS species are not transmitted to another lake. All sample bottles and data sheets will be delivered preferably to WLI to be processed and then sent to MFWP in Helena to be identified in the lab for further analysis.

Zebra and Quagga Mussel Artificial Substrates

Since zebra and quagga mussels attach themselves to hard surfaces, a modified “Portland Sampler” adapted from Portland State University (PSU) Center for Lakes and Reservoirs will be provided to volunteer monitors.

Figure 2. Artificial Zebra and Quagga Mussel Sampler AKA “Portland Sampler”.

Figure 3. Display Showing 3-Month Growth of Quagga Mussels from Lake Mead in 2007. (Display by Wen Baldwin, Photo by Allen Pleus)

Volunteers will be provided an artificial settlement substrate to hang on their docks to monitor for mussel colonization. Data is recorded on the data sheet provided. Substrates should be checked once monthly and submitted to WLI by volunteers to indicate signs of presence or absence of any colonization. If there is a positive sighting, proper authorities will be contacted and further steps will need to be taken to determine the extent of colonization. This information will also be submitted to the PSU program and entered in their data base for monitoring efforts in the northwest.

Aquatic Invasive Species General Awareness

Please be on the lookout for aquatic invasive species like the zebra and quagga mussels. If you suspect any of these species in the lake you are monitoring, please take a GPS location if possible and describe—to the best of our ability—the location of your suspect species.  Contact Montana Fish, Wildlife and Parks immediately at 406-752-5501 or the national hotline at 1.877-STOP-ANS, 1.877-786-7267

What You Can Do to Avoid the Spread of Aquatic Invasive Species

Quality Assurance

Personnel from WLI, and possibly a field technician from MFWP, will work with volunteers to ensure data consistency and a level of competency is met. WLI and/or MFWP personnel will try to visit each lake the first time a volunteer will be sampling. In addition, the site visit in late July by WLI and/or MFWP staff will further orient the volunteer in data collection. Quality assurance protocols will also be followed as mentioned in the USEPA 1996 document regarding quality assurance for volunteer monitoring programs.

Data Collection Forms

There are three types of users and two sets of forms:

Users can be citizens, registered volunteers, or environmental technicians.

Data forms are used as follows:

  1. Aquatic Invasive Species (AIS-Volunteer) Data Collection Forms are used by citizens and volunteers,
  2. AIS-ET Data Collection Forms are used by environmental technicians (ET), and
  3. Water Quality Indicator (WQI) Data Collection Forms are used only by registered volunteers (WQI-Volunteer) and environmental technicians (WQI-ET).

These forms can be completed and submitted online through the Northwest Montana Lakes Volunteer Monitoring Network website, downloaded from the website and printed, or they are available through the Whitefish Lake Institute's office as PDF documents.

See Volunteers/Data Forms for the PDF versions of these forms.


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