USGS Science⌕ Search
Home/Archive/USGS

USGS · 70026262

A simple analytical procedure to replace HPLC for monitoring treatment concentrations of chloramine-T on fish culture facilities

V. K. Dawson·J.R. Meinertz·L.J. Schmidt·W.H. Gingerich
View original source ↗Export metadata ↓

Abstract

Concentrations of chloramine-T must be monitored during experimental treatments of fish when studying the effectiveness of the drug for controlling bacterial gill disease. A surrogate analytical method for analysis of chloramine-T to replace the existing high-performance liquid chromatography (HPLC) method is described. A surrogate method was needed because the existing HPLC method is expensive, requires a specialist to use, and is not generally available at fish hatcheries. Criteria for selection of a replacement method included ease of use, analysis time, cost, safety, sensitivity, accuracy, and precision. The most promising approach was to use the determination of chlorine concentrations as an indicator of chloramine-T. Of the currently available methods for analysis of chlorine, the DPD ( N , N -diethyl- p -phenylenediamine) colorimetric method best fit the established criteria. The surrogate method was evaluated under a variety of water quality conditions. Regression analysis of all DPD colorimetric analyses with the HPLC values produced a linear model ( Y =0.9602 X +0.1259) with an r 2 value of 0.9960. The average accuracy (percent recovery) of the DPD method relative to the HPLC method for the combined set of water quality data was 101.5%. The surrogate method was also evaluated with chloramine-T solutions that contained various concentrations of fish feed or selected densities of rainbow trout. When samples were analyzed within 2 h, the results of the surrogate method were consistent with those of the HPLC method. When samples with high concentrations of organic material were allowed to age more than 2 h before being analyzed, the DPD method seemed to be susceptible to interference, possibly from the development of other chloramine compounds. However, even after aging samples 6 h, the accuracy of the surrogate DPD method relative to the HPLC method was within the range of 80–120%. Based on the data comparing the two methods, the U.S. Food and Drug Administration has concluded that the DPD colorimetric method is appropriate to use to measure chloramine-T in water during pivotal efficacy trials designed to support the approval of chloramine-T for use in fish culture.

Explore related subjects

AquacultureArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

V. K. Dawson, J.R. Meinertz, L.J. Schmidt, W.H. Gingerich. 2003. A simple analytical procedure to replace HPLC for monitoring treatment concentrations of chloramine-T on fish culture facilities. https://doi.org/10.1016/s0044-8486(02)00425-8

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Genomic selection for low salinity tolerance in the eastern oyster Crassostrea virginica in Louisiana and Chesapeake Bay populations

The use of genomic selection (GS) to improve traits of interest in aquaculture species is growing with the availability of genomic resources for those species. The eastern oyster , Crassostrea virginica , is a major aquaculture product and keystone species along the U.S. mid-Atlantic and Gulf coasts. Populations and production of C. virginica are threatened by several environmental stressors, and in certain coastal regions, episodic low salinity conditions have contributed to mass mortality events. Here we examined the potential for genomic selection to improve tolerance to extreme low salinity (≤ 2) in eastern oysters and report the evaluation of GS models for C. virginica from two regions- Louisiana and Chesapeake Bay. Tissue samples from both mortalities and survivors of the lab-based salinity challenges (salinity 2, 28 °C) were genotyped on the 66 K C. virginica SNP array. We performed a genome wide association study (GWAS) for both challenges and then evaluated the effects of several different parameters on GS prediction accuracy, including model type (GBLUP, Bayesian, and weighted), data filtering, Bayesian modelling parameters, and trait encoding (Gaussian, ordinal, and censored). GWAS revealed a significant region on chromosome 1 in the Chesapeake animals while the Louisiana animals showed only a few significantly associated loci. GS model type had no significant impact on prediction accuracy in the Chesapeake animals, but a large impact in the Louisiana animals. Likewise, prediction accuracy remained consistent in the Chesapeake Bay challenge with as few as 5000 markers, while accuracy in the Louisiana challenge began to decline with fewer than 25,000 markers. This likely reflects the lower relatedness among the Louisiana individuals due to unintended wild overset. Overall, with moderate prediction accuracies (∼0.45–0.55) in both regions, GS shows the potential to improve low salinity tolerance in eastern oysters. This will be beneficial to selective breeding programs and restoration efforts in regions where this trait improves oyster survival.

Louisiana, Maryland, Virginia↗
USGS2024

Effect of florfenicol administered through feed on Atlantic salmon (Salmo salar) gut and its microbiome

Although concerns about the impacts of antibiotics in aquatic organisms are reported worldwide, the potential adverse effects on fish gut microbial communities and fish health are still not well known. In this study, we investigated the effects of florfenicol (FFC) on the gut microbiome and gastrointestinal (GIT) gene expression in juvenile Atlantic salmon ( Salmo salar ). Three doses of FFC were used to coat experimental feed at 10, 20 and 30 mg/kg/ fish body weight (bw). The feed was administered for 18 days, followed by a 10-day recovery period. The metatranscriptome analysis revealed that 10 and 30 mg/kg bw of FFC led to the downregulation of genes involved in the transcription of NADH-ubiquinone oxidoreductase chain-1, suggesting that the antibiotic targets bacterial respiratory metabolism. The 30 mg/kg bw FFC treatment upregulated genes that encode glycolytic enzymes, such as phosphoglycerate kinase, indicating a disruption of energy metabolism in the microbiome. Analysis of the fish host transcriptome showed that the FFC treatment affected cellular processes in the GIT system of fish, including pathways related to apoptosis and DNA metabolism. The 30 mg/kg bw FFC treatment specifically activated pathways related to cellular regulation, including LXR/RXR activation, FXR/RXR activation, and protein ubiquitination. At the end of the recovery phase, the 30 mg/kg bw FFC treated group altered pathways related to EIF2 signaling and lysine degradation.

Aquaculture↗
USGS2024

Rates of osmoconformation in triploid eastern oysters, and comparison to their diploid half-siblings

Triploid eastern oysters ( Crassostrea virginica ) suffer greater mortalities than diploids in the U.S. Gulf of Mexico estuaries when extreme low salinities (< 5) and elevated temperatures (≥ 28 °C) coincide. To investigate potential causes, changes in plasma osmolality, hemolymph pH, valve opening and mortality in diploid and triploid oyster half-siblings were compared during a step-down gradual acclimation from a salinity of 5 to 1 (5, 2.5, 2.0, 1.5, 1.0) at 23 °C (expt 1) and at 28 °C (expt 2). To further explore differences in diploid and triploid oyster responses to changing salinity, we compared their plasma osmolality after abrupt decreases in salinity from 20 to 10 and 5, followed by increases in salinity from 5 and 10 to 20 once oysters had osmoconformed to the lowered salinities (expt 3). Lastly, changes in wet weights of mantle tissue explants were compared between diploid and triploid oysters every 10 min for 40 min after being transferred from a salinity of 20 to 10 (expt 4). Oysters of both ploidies were able to osmoconform to water at salinities between 5 and 1.5. After a decrease in salinity, triploid oysters were slower to open their valves and osmoconform, were less efficient in maintaining acid-base status enduring longer periods of acidic hemolymph pH, and were less efficient in regulating tissue water content compared to half-sibling diploid oysters. At a salinity of 1.0, plasma of both diploid and triploid oysters remained hyperosmotic, their hemolymph acidic and their valves closed. Oysters osmoconformed faster at 28 °C than at 23 °C, but the combination of low salinity (≤ 1.5) and higher temperature caused rapid mortalities regardless of ploidies. Triploid oysters, however, started dying earlier and at greater percentages when salinity of 1.5 and temperature of 28 °C were combined. Triploids have been embraced as a means to support higher production, but results indicate superimposed stressors, such as low salinity and high temperature, may be more lethal to triploid than diploid oysters.

Aquaculture↗