Geology topics

Susan M. Schleis

Publications and source records attributed to Susan M. Schleis.

10 recordsLinked to original sources

USGS2024

Summary of data collected during field efficacy trials of florfenicol and oxytetracycline dihydrate in controlling mortality in walleye (Sander vitreus) because of motile Aeromonad infections

Motile Aeromonad septicemia is a substantial concern during fish propagation and can be catastrophic for fish hatcheries. We tested the efficacy of two different drugs (florfenicol and oxytetracycline) offered with feed as possible treatment options to control mortality because of motile Aeromonad infection. We offered top-coated medicated feeds to hatchery-reared Sander vitreus (walleye) that were naturally infected with motile Aeromonad infection during two separate trials in 2011 and 2012. Substantial walleye mortality occurred before positive clinical outcomes from the medicated feed treatments were observed, and additional treatment measures were taken by hatchery staff to mitigate further mortality in their walleye production tanks. This report summarizes the data that were collected during medicated feed trials. Statistical inferences on treatment efficacy are not included because of the confounding treatments and possible secondary pathogens present throughout this study.

Open-File Report↗

USGS2023

Efficacy of hydrogen peroxide to reduce Gyrodactylus species infestation density on four fish species

Objective The ability to effectively treat parasitic infestations of fish is of high importance for fish culture facilities. However, tools or approved therapies for treating infestations on fish are limited. This paper summarizes results from four separate clinical field studies that evaluated the efficacy of hydrogen peroxide (H 2 O 2 ; 35% PEROX-AID) for reducing Gyrodactylus spp. infestation density. Methods Three species of Gyrodactylus were studied ( G. salmonis , hosts: Brook Trout Salvelinus fontinalis and Lake Trout S. namaycush ; G. freemani , host: Yellow Perch Perca flavescens ; G. hoffmani , host: Fathead Minnow Pimephales promelas ) before and after the application of immersion H 2 O 2 therapy. Result Parasite density was significantly reduced for each parasite × host combination to which H 2 O 2 therapy was applied. Two clinical field studies in salmonids were found to demonstrate substantial effectiveness that enabled 35% PEROX-AID approval. Conclusion Further assessments of Gyrodactylus spp. could expand the use of H 2 O 2 for controlling these parasites in aquaculture. Specifically, H 2 O 2 was effective at all levels tested (50 or 75 mg H 2 O 2 /L for 60 min for the Yellow Perch and Fathead Minnow clinical field studies; 100 or 150 mg H 2 O 2 /L for 30 min regardless of salt pre-treatment for the Brook Trout study; and 100 mg H 2 O 2 /L for 30 min or 50 mg H 2 O 2 /L for 60 min for the Lake Trout study).

Journal of Aquatic Animal Health↗

USGS2022

Effects of formaldehyde (Parasite-S®) on biofilter nitrification from a cold- and a warm freshwater RAS

The effect of Parasite-S® (an aqueous formaldehyde solution) on the nitrification processes of biofilters was evaluated in two recirculating aquaculture systems (RASs). Rearing tanks in the warmwater RAS contained yellow perch ( Perca flavescens ) and grass carp ( Ctenopharyngodon idella ) with an initial weight of 166.8 kg and a mean density of 39.5 kg/m 3 . Rearing tanks in the coldwater RAS contained rainbow trout ( Oncorhynchus mykiss ) and lake trout ( Salvelinus namaycush ) with an initial weight of 1377.8 kg at a system density of 41.9 kg/m 3 . Parasite-S® was administered to the entire system on four consecutive days in both trials to achieve a nominal concentration of 14.8 mg/L formaldehyde (40 mg/L formalin) at the biofilter. Removal efficiencies for total ammonia nitrogen (TAN) and nitrite nitrogen were measured as indicators of biofilter nitrification processes. The active ingredient in Parasite-S®, formaldehyde, was measured until it was below the method detection limit of 0.8 mg/L. TAN volumetric removal rate was significantly decreased in both systems after formaldehyde addition and remained below pre-exposure efficiency in the coldwater RAS. Nitrite nitrogen volumetric removal rate was not significantly different, but the slope and intercepts were less after formaldehyde addition indicating an effect on the nitrifying bacteria. Although removal rates were decreased, no mortality occurred after four consecutive formaldehyde indefinite bath exposures in either system.

Aquaculture Research↗

USGS2018

Effects of formaldehyde on nitrification in biofilters of small‐scale recirculating systems

Florfenicol (Aquaflor®) is the only U.S. Food and Drug Administration (FDA) approved drug for treating diseased fish reared in recirculating aquaculture systems (RAS). Treating diseased fish in RAS is challenging because of the potential to damage nitrifying bacteria in the biofilters. Impaired nitrification can lead to concentrations of ammonia and nitrite that compromise fish welfare. The objective of this study was to determine the effects of a FDA‐approved parasiticide and fungicide, Parasite‐S ® (formalin), on biofilter nitrification. Stable biofilters were exposed once to 0, 9.25, 18.5, 37, or 55.5 mg/L formaldehyde. Total ammonia nitrogen (TAN) and nitrite nitrogen were monitored daily before and throughout the study to quantify biofilter function. Formaldehyde concentrations ≥37 mg/L increased TAN and nitrite nitrogen concentrations, and nitrification did not recover to pre‐exposure concentrations up to 8 day postexposure. On the basis of those results, a second trial was conducted. Stable biofilters were exposed once or on four consecutive days to 9.25 or 18.5 mg/L formaldehyde. Biofilters repeatedly exposed to formaldehyde showed signs of impairment and had variable recovery relative to single exposures. Results of this study may help identify formaldehyde concentrations that can be safely applied to RAS when treating diseased fish.

Aquaculture Research↗

USGS2018

Field evaluation of carbon dioxide as a fish deterrent at a water management structure along the Illinois River

Construction of a water management structure (WMS) in the levee surrounding The Nature Conservancy’s Emiquon Preserve (Havana, Illinois, USA) created a new hydrological connection and potential aquatic invasive species pathway between the Illinois River and a large conservation wetland complex. Site managers need a control tool that deters the upstream passage of non-native fishes into the wetland lakes, but does not interfere with normal gate operation and water discharge. This short field study evaluated carbon dioxide (CO 2 ) injected into water as a non-obstructive method to reduce fish abundance near the WMS culverts. We quantified relative fish abundance using underwater sonar with and without injection of CO 2 into culverts during three discharge events: no flow (0 m 3 /s), restricted flow (0.9 m 3 /s), and unrestricted flow (3.2 m 3 /s). Overall, CO 2 reached or exceeded our target concentration of 100 mg/L during no flow and restricted flow, and fish abundance was 70–95% lower at culvert entrances relative to untreated control days. The target CO 2 level was not reached during unrestricted flow and fish abundance was not reduced during CO 2 injection. Atmospheric CO 2 concentrations were inconsequential and unaffected by CO 2 treatments throughout testing. Results from this initial field study provide several considerations for CO 2 as a fish deterrent in natural environments.

Illinois↗

USGS2017

Live transport of Yellow Perch and Nile Tilapia in AQUI-S 20E (10% Eugenol) at high loading densities

Fish transport costs are a substantial portion of the operational expenses for aquaculture facilities in the USA. Safely transporting higher loading densities of fish would benefit haulers by increasing efficiency and reducing costs, but research evaluating transport for individual species is generally lacking. In this study, Yellow Perch Perca flavescens and Nile Tilapia Oreochromis niloticus were transported for 6 h immersed in water containing AQUI-S 20E (10% eugenol) at fish loading densities of 240 g/L (2 lb/gal) for perch and 480 g/L (4 lb/gal) for tilapia. Survival was quantified for fish transported in AQUI-S 20E concentrations of (1) control or 0 mg/L of water, (2) 100 mg/L, or (3) 200 mg/L. Yellow Perch had 98–100% survival, and Nile Tilapia had 100% survival up to through 14 d after transport across all AQUI-S 20E levels, including the control. Eugenol concentrations decreased rapidly in transport tank water, and fish showed no signs of sedation by the end of transport. We conclude that live transport of Yellow Perch and Nile Tilapia at higher loading densities resulted in high survival regardless of the AQUI-S 20E concentrations we tested.

North American Journal of Aquaculture↗

USGS2016

Effects of carbon dioxide on juveniles of the freshwater mussel ( Lampsilis siliquoidea [Unionidae])

Carbon dioxide (CO 2 ) has shown promise as a tool to control movements of invasive Asian carp, but its effects on native freshwater biota have not been well studied. The authors evaluated lethal and sublethal responses of juvenile fatmucket ( Lampsilis siliquoidea ) mussels to CO 2 at levels (43–269 mg/L, mean concentration) that bracket concentrations effective for deterring carp movement. The 28-d lethal concentration to 50% of the mussels was 87.0 mg/L (95% confidence interval [CI] 78.4–95.9) and at 16-d postexposure, 76.0 mg/L (95% CI 62.9–90.3). A proportional hazards regression model predicted that juveniles could not survive CO 2 concentrations >160 mg/L for more than 2 wk or >100 mg/L CO 2 for more than 30 d. Mean shell growth was significantly lower for mussels that survived CO 2 treatments. Growth during the postexposure period did not differ among treatments, indicating recovery of the mussels. Also, CO 2 caused shell pitting and erosion. Behavioral effects of CO 2 included movement of mussels to the substrate surface and narcotization at the highest concentrations. Mussels in the 110 mg/L mean CO 2 treatment had the most movements in the first 3 d of exposure. If CO 2 is infused continuously as a fish deterrent, concentrations <76 mg/L are recommended to prevent juvenile mussel mortality and shell damage. Mussels may survive and recover from brief exposure to higher concentrations.

Environmental Toxicology and Chemistry↗

USGS2014

Effectiveness of Aquaflor (50% florfenicol) administered in feed to control mortality associated with Streptococcus iniae in tilapia at a commercial tilapia production facility

The efficacy of Aquaflor (florfenicol; FFC) to control mortality caused by Streptococcus iniae in tilapia was evaluated under field conditions. The trial was initiated following presumptive diagnosis of S. iniae infection in a mixed group of fingerling (mean, 4.5 g) Nile Tilapia Oreochromis niloticus and a hybrid of Nile Tilapia×Blue Tilapia O. aureus . Diagnoses included mortality in source tank; examination of clinical signs and presence or absence of gram-positive cocci in brain, and collection of samples for microbiological review and disease confirmation of 60 moribund fish. Following presumptive diagnosis, tilapia (83/tank) were randomly transferred to each of 20 test tanks receiving the same water as the source tank (test tank water was not reused). Tilapia were offered either nonmedicated control feed or FFC-medicated feed (FFC at 15 mg/kg body weight/d; 10 tanks per regimen) for 10 consecutive days followed by a 14-d observation period during which only the nonmedicated control feed was offered. Streptococcus iniae was presumptively identified during pretreatment necropsy and confirmed by polymerase chain reaction assay; S. iniae was confirmed in samples taken during the dosing period but was not detected during the postdosing period. The FFC disk diffusion zone of inhibition ranged from 29 to 32 mm, while the minimum inhibitory concentration of FFC ranged from 2 to 4 μg/mL for the S. iniae isolates collected. Survival of tilapia assigned to the FFC-dose group was significantly greater at 14 d posttreatment than that of the nonmedicated controls. The odds of tilapia assigned to the FFC-dose group surviving to the end of the postdosing period were 1.34 times the odds of survival of tilapia assigned to the nonmedicated control group. There were no clinically apparent adverse effects associated with the administration of FFC-medicated feed in this study.

North American Journal of Aquaculture↗

USGS2013

Depletion of florfenicol amine in tilapia (Oreochromis sp.) maintained in a recirculating aquaculture system following Aquaflor®-medicated feed therapy

Aquaflor ® [50% w w −1 florfenicol (FFC)], is approved for use in freshwater‐reared warmwater finfish which include tilapia Oreochromis spp. in the United States to control mortality from Streptococcus iniae . The depletion of florfenicol amine (FFA), the marker residue of FFC, was evaluated after feeding FFC‐medicated feed to deliver a nominal 20 mg FFC kg −1 BW d −1 dose (1.33× the label use of 15 mg FFC kg −1 BW d −1 ) to Nile tilapia O. niloticus and hybrid tilapia O. niloticus × O. aureus held in a recirculating aquaculture system (RAS) at production‐scale holding densities. Florfenicol amine concentrations were determined in fillets taken from 10 fish before dosing and from 20 fish at nine time points after dosing (from 1 to 240 h post‐dosing). Water samples were assayed for FFC before, during and after the dosing period. Parameters monitored included daily feed consumption and biofilter function (levels of ammonia, nitrite and nitrate). Mean fillet FFA concentration decreased from 13.77 μg g −1 at 1‐h post dosing to 0.39 μg g −1 at 240‐h post dosing. Water FFC concentration decreased from a maximum of 1400 ng mL −1 at 1 day post‐dosing to 847 ng mL −1 at 240 h post‐dosing. There were no adverse effects noted on fish, feed consumption or biofilter function associated with FFC‐medicated feed administration to tilapia.

Aquaculture Research↗

USGS2012

Safety of florfenicol administered in feed to tilapia (Oreochromis sp.)

The safety of Aquaflor® (50% w/w florfenicol [FFC]) incorporated in feed then administered to tilapia for 20 days (2x the recommended duration) at 0, 15, 45, or 75 mg/kg body weight/day (0, 1, 3, or 5x the recommended dose of 15 mg FFC/kg BW/d) was investigated. Mortality, behavioral change, feed consumption, body size, and gross and microscopic lesions were determined. Estimated delivered doses were >96.9% of target. Three unscheduled mortalities occurred but were considered incidental since FFC-related findings were not identified. Feed consumption was only affected during the last 10 dosing days when the 45 and 75 mg/kg groups consumed only 62.5% and 55.3% of the feed offered, respectively. There were significant, dose-dependent reductions in body size in the FFC-dose groups relative to the controls. Treatment-related histopathological findings included increased severity of lamellar epithelial hyperplasia, increased incidence of lamellar adhesions, decreased incidence of lamellar telangiectasis in the gills, increased glycogen-type and lipid-type hepatocellular vacuolation in the liver, decreased lymphocytes, increased blast cells, and increased individual cell necrosis in the anterior kidney, and tubular epithelial degeneration and mineralization in the posterior kidney. These changes are likely to be of minimal clinical relevance, given the lack of mortality or morbidity observed. This study has shown that FFC, when administered in feed to tilapia at the recommended dose (15 mg FFC/kg BW/day) for 10 days would be well tolerated.

Toxicologic Pathology↗