Geology topics

R.T. Ramsay

Publications and source records attributed to R.T. Ramsay.

3 recordsLinked to original sources

USGS2000

Analytical verification of waterborne chemical treatment regimens in hatchery raceways

Chemical therapy for control and prevention of fish diseases is a necessary and common practice in aquaculture. Many factors affect the accuracy of a chemical treatment application, such as the functioning of the chemical delivery system, calculation of chemical quantities to be delivered, water temperature, geometry of the culture unit, inlet-outlet structure, the influence of aerators, wind movement, and measurement of water volumes and flow rates. Three separate trials were conducted at the Osceola Fish Hatchery, a facility of the Wisconsin Department of Natural Resources, evaluating the accuracy of flow-through hydrogen peroxide treatments applied to 1, 3, or 9 raceways that were connected in series. Raceways were treated with 50 or 75 ??L/L of hydrogen peroxide for 30 min. Chemical concentrations were determined titrimetrically. The target treatment regimen was not realized in any of the applications. Chemical concentrations dropped and exposure times increased with each additional raceway treated in series. Single introduction of a therapeutant to more than three raceways in series is not recommended. Factors that interfered with the accuracy of the treatments were culture unit configuration, aeration, and flow rates. Several treatment modifications were identified that would result in more accurate chemical treatments.

North American Journal of Aquaculture↗

USGS1999

Acute toxicity of hydrogen peroxide treatments to selected lifestages of cold-, cool-, and warmwater fish

Hatchery personnel depend on therapeutant treatments to control diseases. Currently, hatchery managers in the United States are limited to one approved therapeutant (formalin) and three compounds of Low Regulatory Priority (sodium chloride, hydrogen peroxide, and acetic acid) to control external diseases of cultured fish. Hydrogen peroxide has been used to effectively control external columnaris and bacterial gill disease in rainbow trout, however, definitive safe treatment concentrations for hydrogen peroxide are lacking for a variety of species. We report the acute toxicity of hydrogen peroxide treatments to 11 species of fry and 13 species of fingerling freshwater fish. Most mortality occurred within the first 30 h after the first exposure to hydrogen peroxide with little change in the overall shape of survival curves over time. Our data predict that in an actual therapeutic application of hydrogen peroxide, most treatment-related mortalities would be observed shortly after the initial exposure. Coolwater species were more sensitive than coldwater species but were generally similar to warmwater species tested. Based on our mortality data, coldwater species and largemouth bass may be treated for 60 min at concentrations of ??? 150 ??l/l without harmful effects; all muskellunge, walleye, bluegill, channel catfish, yellow perch, pallid sturgeon fingerlings, fathead minnow fingerlings, white sucker fingerlings, and northern pike fry may be treated for 60 min at ??? 100 ??l/l; and northern pike fingerlings and white sucker, yellow perch and fathead minnow fry may be treated for 60 min at ??? 50 ??l/l.

Aquaculture↗

USGS1998

Toxicity of hydrogen peroxide treatments to rainbow trout eggs

Hydrogen peroxide treatments of 0, 500, 1,000, and 3,000 I?L/L, concentrations that were multiples of the Low Regulatory Priority limit of 500 I?L/L, were administered for 15 min every weekday (Mondaya??Friday) to eggs of rainbow trout Oncorhynchus mykiss and steelhead (anadromous rainbow trout) to determine the margin of safety existing for standard egg treatments. All untreated and treated eggs remained free of fungal infection throughout incubation. Hydrogen peroxide treatment reduced the mean percent hatch of rainbow trout eggs by 1.4a??5.9% among those treated at 500 I?L/L, 6.8a??15.4% among those treated at 1,000 I?L/L, and 13.2a??25.3% among those treated at 3,000 I?L/L. Mean percent hatch of rainbow trout eggs treated at 1,000 I?L H2O2/L was 7% lower than that for eggs treated at 500 I?L H2O2/L. Mean percent hatch of Skamania strain steelhead was significantly reduced by hydrogen peroxide treatment, whereas the mean percent hatch of Ganaraska strain steelhead was similar to the mean percent hatch of rainbow trout eggs. Daily percent mortality of rainbow trout eggs increased significantly from day 6 to day 10 (78a??135 daily temperature units, DTUsA?C) of incubation. Discontinuing hydrogen peroxide treatments to Skamania strain steelhead eggs from day 7 to day 11 (78a??105 DTUsA?C) of incubation significantly increased the probability of eggs reaching the eyed egg stage. The mean percent hatch of rainbow trout eggs treated with hydrogen peroxide at concentrations up to 1,000 I?L/L may be increased if no treatments are administered between 70 and 140 DTUsA?C. Mortality of sac fry was not observed at hydrogen peroxide concentrations of 1,000 I?L/L or lower. Fish culturists should be aware that other species or strains may be more sensitive than rainbow trout. Other species and strains should be initially treated with hydrogen peroxide at 500 I?L/L until monitoring of egg mortality identifies the presence or absence of a sensitive period.

Journal of Aquatic Animal Health↗