Zebra Mussel Monitoring Program

Artificial Substrates and Analysis

Late-stage dreissenid larvae (veligers) settle out of the water column and attach to substrates by using proteinaceous byssal threads. Often, dreissenid mussels will settle on hard substrates (e.g. pipes, screens, rocks, and other mussels) but can settle on soft substrates (e.g. plants, rope, and Styrofoam). After settlement, mussels metamorphose into juveniles.

As a complement to visual inspections, ZMMP personnel prepare artificial substrates that mimic desirable natural substrate characteristics. These artificial substrates are deployed at most study sites, and are used as passive samplers to monitor the settlement and growth of dreissenid mussel juveniles and adults.

At Reservoirs

Artificial substrate boards, almost completely obscured with zebra mussels, resting against the side of a boat after being pulled from the water.

Artificial substrates for reservoirs are constructed of a series of stacked 4- by 4-inch hardboard tiles separated with 0.25-inch spacers.

At Rivers and Creeks

Zebra mussels attached to cinder block

Cinderblocks are used for adult zebra mussel passive sampling to withstand the higher water velocities on rivers and creeks.

Inspection

Scientist standing in a boat (only the lake and shoreline are visible), wearing blue latex gloves and holding a passive ZM sampler

Samplers are visually inspected in the field. Currently, all adult zebra mussels detected in the field are quantified and measured at the USGS North Texas Program–Fort Worth laboratory.

Lab Analysis

Four zebra mussels, as collected, outlined and superimposed with measurements of 9.79 mm, 12.19 mm, 9.26mm, and 13.79 mm

If mussels are detected, they are analyzed in the laboratory by using a stereomicroscope. Mussel density (mussels per square meter) is determined and the shell lengths of a subset of individuals are recorded.

Additional Photos

Place your cursor on the photo for the image caption. Click on the photo to see a larger view.

Assembled substrate in the foreground, on a stack of unassembled substrate boards, with multiple columns of the boards in the background
Artificial substrate (4-by-4 inch hardboard tiles) being prepared for deployment
USGS scientist lowering artificial substrate into the lake
USGS scientist lowering artificial substrate into the lake
Two artificial substrate boards; one clean, the other completely obscured with zebra mussels
Artificial substrate covered in zebra mussels next to clean artificial substrate
Single adult zebra mussel attached to artificial substrate
Adult zebra mussel attached to artificial substrate
Adult zebra mussels attached to artificial substrate
Adult zebra mussels attached to artificial substrate
Juvenile zebra mussel attached to artificial substrate
Juvenile zebra mussel attached to artificial substrate
USGS scientists in the lab taking apart artificial substrate to count and measure attached zebra mussels
USGS scientists in the lab taking apart artificial substrate to count and measure attached zebra mussels
Adult zebra mussels attached to artificial substrate
Adult zebra mussels attached to artificial substrate