A mobile bioassay trailer was used to assess the efficacy of Pseudomonas fluorescens (Pf-CL145A) spray dried powder (SDP) formulation for controlling zebra mussels (Dreissena polymorpha) from two midwestern lakes: Lake Carlos (Alexandria, Minnesota) and Shawano Lake (Shawano, Wisconsin). The effects of SDP exposure concentration and exposure duration on zebra mussel survival were evaluated along with the evaluation of a benthic injection application technique to reduce the amount of SDP required to induce zebra mortality.

Groups of zebra mussels were collected from each lake and allowed to adhere to test substrates for at least 15 days before exposure to SDP. Two independent trials were completed at each lake: (1) a whole water column (WWC) application trial was used to evaluate the effects of SDP exposure concentration and exposure duration on zebra mussel survival; and (2) a benthic injection (BI) application trial in which the SDP was injected into the test tanks to determine the efficacy of a benthic injection application technique to reduce the amount of SDP required to induced zebra mussel mortality. Three exposure durations (6, 9, and 12 hours) were evaluated in the WWC trials and a 12-hour exposure duration was evaluated in the BI trials. All trials contained zebra mussels which were removed at the completion of each exposure duration, consolidated into wire mesh cages, and held in the lake for approximately 30 days before being assessed for survival.

The efficacy of a commercially prepared spray dried powder (SDP) formulation of Pseudomonas fluorescens (strain CL145A) was evaluated for removing zebra mussels (Dreissena polymorpha) adhering to a population of unionid mussels in Lake Darling (Alexandria, Minnesota). Two groups of unionid mussels were used in the study. Unionid mussels were collected near the test area, weighed, photographed, individually tagged, and randomly allocated to one of nine test enclosures in equal proportions and then divided into two groups. The first group of unionid mussels (Group 1, n = 5 per test enclosure) were indiscriminately selected from each test enclosure and used to estimate the number of zebra mussels adhering to unionid mussels prior to exposure. The second group of unionid mussels (Group 2, n = 22 per test enclosure) were used to evaluate the efficacy of SDP for removal of adhering zebra mussels. Both Group 1 and Group 2 mussels were used to evaluate the effects of SDP exposure on unionid mussel survival.

Treatment was assigned to each test enclosure by using a randomized block design. The three treatment groups were tested in triplicate and included an untreated control group and groups that received a single application of 50 or 100 milligrams per liter (mg/L) of SDP based on active ingredient. All treatment concentrations are reported as active ingredient of SDP. Test enclosures were removed at the 8-hour exposure termination. Both Group 1 and Group 2 mussels remained in their assigned exposure location during the postexposure holding period. The number of zebra mussels adhering to Group 2 mussels (live and dead) was assessed 18 to 20 days postexposure in addition to assessing the survival of Group 1 and Group 2 unionid mussels.

The efficacy of a commercially prepared spray dried powder (SDP) formulation of Pseudomonas fluorescens (strain CL145A) was evaluated for removing zebra mussels (Dreissena polymorpha) adhering to a population of unionid mussels in Lake Darling (Alexandria, Minnesota). Two groups of unionid mussels were used in the study. Unionid mussels were collected near the test area, weighed, photographed, individually tagged, and randomly allocated to one of nine test enclosures in equal proportions and then divided into two groups. The first group of unionid mussels (Group 1, n = 5 per test enclosure) were indiscriminately selected from each test enclosure and used to estimate the number of zebra mussels adhering to unionid mussels prior to exposure. The second group of unionid mussels (Group 2, n = 22 per test enclosure) were used to evaluate the efficacy of SDP for removal of adhering zebra mussels. Both Group 1 and Group 2 mussels were used to evaluate the effects of SDP exposure on unionid mussel survival.

Treatment was assigned to each test enclosure by using a randomized block design. The three treatment groups were tested in triplicate and included an untreated control group and groups that received a single application of 50 or 100 milligrams per liter (mg/L) of SDP based on active ingredient. All treatment concentrations are reported as active ingredient of SDP. Test enclosures were removed at the 8-hour exposure termination. Both Group 1 and Group 2 mussels remained in their assigned exposure location during the postexposure holding period. The number of zebra mussels adhering to Group 2 mussels (live and dead) was assessed 18 to 20 days postexposure in addition to assessing the survival of Group 1 and Group 2 unionid mussels.

The exposure effects of a commercially prepared spray dried powder (SDP) formulation ofPseudomonas fluorescens\ (strain CL145A) on the survival of seven species of unionid mussels endemic to the Great Lakes and Mississippi River basins was evaluated in this study. The study exposures were completed within replicated 350-liter test tanks contained within a mobile bioassay laboratory sited on the shores of the Black River near La Crosse, Wisconsin. The test tanks were supplied with flowing, filtered river water which was interrupted during the exposure period.

Two groups of seven species of mussels were used in equal proportions in the study. The first group was exposed to SDP for 8 hours, and the second group was exposed to SDP for 24 hours. Individually tagged mussels were randomly allocated to test tanks until all test tanks contained 8 to 10 mussels of each species (dependent upon the number available for testing).

The experimental unit for the trial was the individual test tank, and treatment group was assigned using a randomized block design. The treatment groups for each exposure duration consisted of (1) an untreated control group, (2) a group that received an application of 50 milligrams SDP per liter (mg SDP/L), and (3) a group that received an application of 100 mg SDP/L. All mussel species and both exposure duration groups were exposed concurrently (that is, one-half of the mussels were removed after 8 hours of SDP exposure and the remaining mussels were removed after 24 hours of SDP exposure). All treatment concentrations are reported as active ingredient.

After exposure, the mussels were consolidated into wire mesh cages and placed in the Black River for a 27-28 day postexposure period, after which time survival of mussels was assessed. Of the 1,170 mussels tested in the study, 3 were confirmed dead and 5 were not recovered and treated as mortalities in the analysis. The effect and interactions of species, SDP exposure concentration, and SDP exposure duration were analyzed and did not affect mussel survival (p \> 0.98). The results from this study indicate that SDP exposure at the maximum approved open-water concentration of 100 mg/L for up to 3 times the maximum approved open-water exposure duration of 8 hours (in other words for 24 hours of exposure) is unlikely to reduce survival of subadult or adult mussels.

The exposure-related effects of a commercially prepared spray-dried powder (SDP) or freeze-dried powder (FDP) formulation of Pseudomonas fluorescens (strain CL145A) on the survival of seven species of newly metamorphosed (\<72 hours old) freshwater unionid mussels was evaluated. Forty unionid mussels of each species were randomly distributed to test chambers and each species independently exposed for 24 hours to a static dose of either SDP (four species: Lampsilis cardium, Lampsilis siliquoidea, Lampsilis higginsii, and Ligumia recta) or FDP (three species: Obovaria olivaria, Actinonaias ligamentina, and Megalonaias nervosa).

The exposure-related effects of a commercially prepared spray-dried powder (SDP) or freeze-dried powder (FDP) formulation of Pseudomonas fluorescens (strain CL145A) on the survival of seven species of newly metamorphosed (\<72 hours old) freshwater unionid mussels was evaluated. Forty unionid mussels of each species were randomly distributed to test chambers and each species independently exposed for 24 hours to a static dose of either SDP (four species: Lampsilis cardium, Lampsilis siliquoidea, Lampsilis higginsii, andLigumia recta) or FDP (three species: Obovaria olivaria, Actinonaias ligamentina, andMegalonaias nervosa).

A mobile bioassay trailer was used to assess the efficacy of\ Pseudomonas fluorescens\ (Pf-CL145A) spray dried powder (SDP) formulation for controlling zebra mussels (Dreissena polymorpha) from two midwestern lakes: Lake Carlos (Alexandria, Minnesota) and Shawano Lake (Shawano, Wisconsin). The effects of SDP exposure concentration and exposure duration on zebra mussel survival were evaluated along with the evaluation of a benthic injection application technique to reduce the amount of SDP required to induce zebra mortality.

Groups of zebra mussels were collected from each lake and allowed to adhere to test substrates for at least 15 days before exposure to SDP. Two independent trials were completed at each lake: (1) a whole water column (WWC) application trial was used to evaluate the effects of SDP exposure concentration and exposure duration on zebra mussel survival; and (2) a benthic injection (BI) application trial in which the SDP was injected into the test tanks to determine the efficacy of a benthic injection application technique to reduce the amount of SDP required to induced zebra mussel mortality. Three exposure durations (6, 9, and 12 hours) were evaluated in the WWC trials and a 12-hour exposure duration was evaluated in the BI trials. All trials contained zebra mussels which were removed at the completion of each exposure duration, consolidated into wire mesh cages, and held in the lake for approximately 30 days before being assessed for survival.