Geology topics

Tawni B. Riepe

Publications and source records attributed to Tawni B. Riepe.

3 recordsLinked to original sources

USGS2023

Vertical transmission of Renibacterium salmoninarum in cutthroat trout (Oncorhynchus clarkii)

Vertical transmission of Renibacterium salmoninarum has been well-documented in anadromous salmonids but not in hatchery-reared inland trout. We assessed whether the bacterium is vertically transmitted in cutthroat trout ( Oncorhynchus clarkii ) from a Colorado, USA hatchery, and assessed the rate of transmission from male and female brood fish. Adult brood fish were killed, tested for R. salmoninarum in kidney, liver, spleen, ovarian fluid, blood and mucus samples , then stripped of gametes to create 32 families with four infection treatments (MNFN, MNFP, MPFN, MPFP; M: male, F: female, P: positive, N: negative). Progeny from each treatment was sampled at 6 and 12 months to test for the presence of R. salmoninarum with an enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. Our study indicated that vertical transmission was high and occurred among 60% of families across all infection treatments. However, the average proportion of infected progeny from individual families was low, ranging from 1% (MNFP, MPFN and MPFP treatments) up to 21% (MPFP treatment). Hatcheries rearing inland salmonids would be well suited to limit vertical transmission through practices such as lethal culling because any amount of transmission can perpetuate the infection throughout fish on a hatchery.

Journal of Fish Diseases↗

USGS2022

Effects of 17α-ethinylestradiol and density on juvenile fathead minnow survival and body size

Anthropogenic changes have led to the increased use of wastewater treatment plants in stream systems near urbanized areas. Synthetic oral contraceptives, observed in wastewater treatment effluents, can cause negative effects on fish life history metrics. Previous exposures of 17α-ethinylestradiol (EE2) have been shown to affect survival and reproduction of fathead minnows ( Pimephales promelas ). However, density effects were not considered, and additional research is needed to examine the role of density among fish exposed to EE2. Multiple hypotheses indicate the interaction of density with contaminant exposure may ameliorate or exacerbate mortality. We examined how nominal EE2 concentrations of 0 ng/L, 5 ng/L, and 10 ng/L affect body size and mortality at various densities. Fish body size was influenced by density but not EE2 exposure. When density was high, we did not detect an effect of EE2 exposure on mortality. However, when density was low, EE2 exposures increased mortality. Thus, toxic effects of EE2 exposures were observable at low density but at high density, density-dependence in body size and mortality overwhelmed the effect of EE2. The results from our study provide insight into the relationship between density and EE2 exposures on fish survival and can be used to adjust population dynamic parameters for more accurate population dynamic estimates.

Journal of Aquatic Pollution and Toxicology↗

USGS2021

Evidence for the use of mucus swabs to detect Renibacterium salmoninarum in brook trout

Efforts to advance fish health diagnostics have been highlighted in many studies to improve the detection of pathogens in aquaculture facilities and wild fish populations. Typically, the detection of a pathogen has required sacrificing fish; however, many hatcheries have valuable and sometimes irreplaceable broodstocks, and lethal sampling is undesirable. Therefore, the development of non-lethal detection methods is a high priority. The goal of our study was to compare non-lethal sampling methods with standardized lethal kidney tissue sampling that is used to detect Renibacterium salmoninarum infections in salmonids. We collected anal, buccal, and mucus swabs (non-lethal qPCR) and kidney tissue samples (lethal DFAT) from 72 adult brook trout ( Salvelinus fontinalis ) reared at the Colorado Parks and Wildlife Pitkin Brood Unit and tested each sample to assess R. salmoninarum infections. Standard kidney tissue detected R. salmoninarum 1.59 times more often than mucus swabs, compared to 10.43 and 13.16 times more often than buccal or anal swabs, respectively, indicating mucus swabs were the most effective and may be a useful non-lethal method. Our study highlights the potential of non-lethal mucus swabs to sample for R. salmoninarum and suggests future studies are needed to refine this technique for use in aquaculture facilities and wild populations of inland salmonids.

Pathogens↗