Peter W. Perschbacher

Publications (9)0 Total impact

• Article: High Drift Rate Effects of Propanil and Basis Gold on the Plankton Communities and Water Quality of a Prestocking Sunshine Bass, Morone chrysops × M. saxatilis, Fry Pond

  Peter W. Perschbacher, Gerald M. Ludwig
  Journal of Applied Aquaculture 01/2007; 19(2):101-112.
• Article: Determination of Geosmin and Methylisoborneol in Catfish Tissue (Ictalurus punctatus) by Microwave-Assisted Distillation−Solid Phase Adsorbent Trapping

  Eric D. Conte, Chun-Yi Shen, Peter W. Perschbacher, Dwight W. Miller
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  ABSTRACT: Methylisoborneol (MIB) and geosmin (GEO) are algal off-flavor compounds, which when present in catfish tissue create undesirable taste and odors in the prepared products. These undesirable taste and odor problems are not limited to catfish aquaculture. A procedure was developed for the determination of off-flavor compounds in channel catfish tissue that involves microwave radiation distillation with solid phase trapping. This is a modification of a microwave distillation−cold trapping procedure but without the need of a cryogen or a liquid−liquid extraction step. A channel catfish fillet sample is placed in a container located within a microwave oven. This container, which is directly connected to a thermostated condenser containing a solid phase adsorbent, is continually purged with argon gas. The trapped distillate components are eluted with ethyl acetate and then injected into a gas chromatograph−ion trap mass spectrometer for analysis. This technique offers a rapid and sensitive means of off-flavor analysis in fish tissue and improved recovery for MIB from 73 ± 3% (50 ppb) to 85 ± 5% (10 ppm) compared to 62 ± 6% for microwave−cold trap collection. The method detection limits are 1.7 and 1.1 ppb for MIB and GEO, respectively. Keywords: Off-flavors; methylisoborneol; geosmin; catfish; microwave-assisted distillation
  03/1996;
• Article: Effects of common aerially applied rice herbicides on the plankton communities of aquaculture ponds

  Peter W Perschbacher, Gerald M Ludwig, Nathan Slaton
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  ABSTRACT: Ten common aerially applied herbicides for rice were tested for possible adverse impacts on pond phytoplankton and zooplankton and critical water quality variables. Treatments simulated direct spraying of ponds and amounts of drift judged able to reach the pond at 1/10 and 1/100 direct rates. The study was conducted in 12, 500-l outdoor pool mesocosms. Pond water from an adjacent baitfish rearing pond was used. Water quality measurements were made prior to application and at 24 and 48 h after application. Commercial compounds tested and direct rates in kg active ingredient ha−1 were clomazone (0.6), thiobencarb (3.4), pendamethalin (1.1), propanil-dry, flowable (4.5), quinclorac (0.6), halosulfuron (0.07), bensulfuron methyl (0.07), triclopyr (0.4), 2,4-d-amine (1.7), and molinate (5.6). In addition, propanil was evaluated in a second application scenario at the same rates and to the same pond water sample as the initial application. Except for propanil, the rice herbicides produced no measurable effect on pond plankton or associated water quality. Following the first application at full rate for propanil, morning oxygen levels were reduced to critical levels (below 3 mg/l) for 2 days. After a second application of propanil at the full and 1/10 rates, oxygen levels were not decreased, although there were significant increases in chlorophyll a and zooplankton concentrations.
  Aquaculture.
• Source

  Available from: ca.uky.edu

  Article: Effects of calcium and magnesium hardness on acute copper toxicity to juvenile channel catfish, Ictalurus punctatus

  Peter W Perschbacher, William A Wurts
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  ABSTRACT: Two experiments were conducted to evaluate the effects of calcium or magnesium hardness on the acute toxicity of copper sulfate to juvenile channel catfish (Ictalurus punctatus) in low alkalinity environments. A preliminary bioassay determined the 48-h LC50 of copper sulfate to be 1.25 mg l−1 for juvenile catfish placed in water with calcium hardness and total alkalinity set at 20 mg l−1 CaCO3. In the first experiment, catfish were exposed to 1.25 mg l−1 copper sulfate in environments where calcium hardness was varied from 10–400 mg l−1 CaCO3. Total alkalinity was 20 mg l−1 CaCO3. As calcium hardness increased, copper-induced catfish mortalities decreased significantly from 90% at 10 mg l−1 CaCO3 to 5% at 400 mg l−1 CaCO3. In the second experiment, catfish were exposed to 1.25 mg l−1 copper sulfate in environments containing either calcium or magnesium hardness, 20 and 400 mg l−1 CaCO3, with total alkalinity set at 20 mg l−1 CaCO3. Survival rates in calcium hardness treatments were consistent with those in the first experiment. However, 100% mortality was observed in both treatments containing magnesium-based hardness. These data suggest a calcium-specific mechanism with respect to acute copper toxicity in channel catfish.
  Aquaculture.
• Source

  Available from: ca.uky.edu

  Article: Effects of bicarbonate alkalinity and calcium on the acute toxicity of copper to juvenile channel catfish (Ictalurus punctatus)

  William A. Wurts, Peter W. Perschbacher
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  ABSTRACT: Three experiments were conducted to evaluate the relative importance of calcium hardness and bicarbonate alkalinity to the acute response of juvenile channel catfish (Ictalurus punctatus) exposed to a toxic concentration of copper sulfate. A preliminary bioassay revealed 28 mg·l−1 copper sulfate caused 50% mortality within 48 h (48-hLC50) in juvenile channel catfish placed in water with calcium hardness and bicarbonate alkalinity, set at 75 mg·l−1 CaCO3. Catfish were then exposed to 28 mg·l−1 copper sulfate concentrations in environments where hardness or alkalinity concentrations were varied. Bicarbonate alkalinities above 75 mg·l−1 CaCO3, with calcium hardness held at 20 mg·l−1 CaCO3, significantly reduced catfish mortalities from 97–100% to 63–70%. Copper-induced mortalities were 100% for all fish placed in calcium hardness treatments (20–250 mg·l−1 CaCO3) in which bicarbonate alkalinity was held at 20 mg·l−1 CaCO3. When bicarbonate alkalinity was held constant at 75 mg·l−1 CaCO3 and calcium hardness was varied from 20 to 250 mg·l−1 CaCO3, copper related catfish mortalities displayed high variability and means ranged from 6.7 to 60%. Mortalities decreased as calcium concentrations increased. Although differences in mortalities were not statistically significant, the latter hardness findings appear to suggest a biologically significant calcium effect on copper toxicity in the presence of sufficient alkalinity concentrations.
  Aquaculture.
• Article: Microwave mediated distillation with solid-phase microextraction: determination of off-flavors, geosmin and methylisoborneol, in catfish tissue

  Ming Zhu, Francisco J. Aviles, Eric D. Conte, Dwight W. Miller, Peter W. Perschbacher
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  ABSTRACT: Presented is a rapid distillation device for use with solid-phase microextraction (SPME). We apply this device specifically for determining two semivolatile off-flavor compounds, methylisoborneol and geosmin, in channel catfish. The presence of these two compounds in channel catfish filets results in unwelcome tastes. In the presented procedure, a catfish tissue sample is placed within a sample container located inside the microwave device. Microwave radiation is applied and distillates formed migrate through a condenser via a purge gas and are collected in a sample vial. A SPME fiber is placed within the stirred collected distillate and methylisoborneol and geosmin are extracted. Qualitative and quantitative results of these extractions are obtained using a gas chromatograph-ion trap mass spectrometer. This solventless technique results in detection limits far below the human threshold for these off-flavor compounds in channel catfish.
  Journal of Chromatography A.
• Article: Evaluation of effects of common aerially-applied soybean herbicides and propanil on the plankton communities of aquaculture ponds

  Peter W. Perschbacher, Nathan Stone, Gerald M. Ludwig, Charles B. Guy
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  ABSTRACT: Eight, common, aerially-applied herbicides for soybeans and the rice herbicide propanil were tested for possible adverse impacts on pond phytoplankton productivity, Zooplankton populations and critical water quality variables. Treatments simulated direct spraying of ponds and bracketed amounts of drift judged able to reach the pond at and direct rates. The study was conducted in 12, 500-1 outdoor pool mesocosms. Pond water was pumped from an adjacent fingerling rearing pond. Water quality measurements were made prior to application and at 24 and 48 h after application. Commercial compounds tested and full rates (kg active ha−1) were fomasefen, aciflourfen and glyphosate (0.43); bentazon (0.57); imazaquin (0.14); fluazifop (0.10); clethodim (0.07); chlorimuron (0.0045); and propanil (0.45 kg). Ten of 1152 soybean herbicide means significantly differed and without pattern. Thus, these herbicides were judged not to affect pond plankton or associated water quality. Propanil at the full rate reduced primary productivity and morning oxygen to critical levels for 3 days.
  Aquaculture.
• Article: Effects of diuron and other aerially applied cotton herbicides and defoliants on the plankton communities of aquaculture ponds

  Peter W. Perschbacher, Gerald M. Ludwig
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  ABSTRACT: Seven aerially applied cotton herbicides and defoliants were tested for possible adverse impacts on pond phytoplankton and zooplankton and critical water quality variables. Treatments simulated direct spraying of ponds and high and low amounts of drift judged able to reach the pond, 1/10 and 1/100 direct rates, respectively. The study was conducted in twelve 500-l outdoor pool mesocosms filled with pond water from an adjacent goldfish Carassius auratus culture pond. Plankton and water quality samples were taken just prior to application and at 24 and 48 h after application. Sampling for chemicals showing effects were continued approximately weekly until oxygen levels in drift treatments returned to no significant difference from control. Chemicals tested and direct rates (kg active ingredient ha−1) were diuron as herbicide (1.4), paraquat (0.83), quizalofop (0.05), dimethipin (0.15), diuron as defoliant (0.1675), ethephon (0.176), tribufos (0.99) and sodium chlorate (5.28). Except for the diuron compounds, the cotton herbicides and defoliants produced no measurable impacts on pond plankton or associated water quality. Following application on March 5 of diuron, used as an herbicide, chlorophyll a levels and photosynthesis were significantly depressed in relation to diuron concentration. Recovery occurred slowly, and at the high drift dosage by week 3 morning oxygen levels returned to near control levels, although chlorophyll a levels were 1/3 the control. However, the off-flavor cyanobacterium, Anabaena laevendri, was essentially eliminated by week 3; and pH and thus un-ionized ammonia were much lower in high drift treatments. Copepod adult and nauplii zooplankton levels were depressed at week 2. However, rotifer numbers increased in the low drift treatment in weeks 3 and 4 and those of copepod nauplii in week 3. Fall application of diuron, as a defoliant at 1/10 the spring rate, produced similar effects when compared by concentration. The main adverse impact of diuron drift is on dissolved oxygen levels and can be anticipated by provision of adequate aeration capacity.
  Aquaculture.
• Article: Determination of methylisoborneol in channel catfish pond water by solid phase extraction followed by gas chromatography-mass spectrometry

  Eric D. Conte, Samuel C. Conway, Dwight W. Miller, Peter W. Perschbacher
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  ABSTRACT: Several compounds exist which are responsible for unwanted taste and odor characteristics that have been found in the edible tissue of the channel catfish (Ictalurus punctatus). Methylisoborneol (MIB), one compound responsible for these off-flavors, is produced through the metabolism of cyanobacteria in aqueous systems such as reservoirs and ponds. The channel catfish accumulates MIB in its tissues from the intake of its culture-pond water. Current methods of analysis for MIB, such as closed- and open-loop stripping, and liquid-liquid extraction, are time-consuming and labor-intensive. A method for the analysis of MIB in catfish culture-pond water is described which, unlike other methods, is rapid, inexpensive, and does not require specialized sample preparation equipment. This method utilizes C18 solid-phase extraction followed by capillary gas chromatography with detection by mass spectrometry. Standard MIB and the internal standard, butylisoborneol (BIB), were prepared from the reaction of d-camphor with methylmagnesium chloride and n-butyllithium, respectively. Extraction efficiencies for MIB in channel catfish pond water averaged 89% at 101 parts per trillion (ppt) and 84% at 202 parts per billion (ppb). The detection limit of the method was calculated to be 11.5 ppt.
  Water Research.