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Rassa Draugelis-Dale, Ph.D.

Rassa Dale is a retired Statistician at the USGS Wetland and Aquatic Research Center.

Rassa Draugelis-Dale is experienced in mathematical/computer modeling and statistical consultations/analyses for a variety of disciplines; initiated, directed and implemented research projects; developed and conducted university lectures, seminars, and workshops; as well as created/instituted curricula and education programs. Her research interests range from mathematical/computer modeling and statistical analyses of biomedical (physiological) and organic/inorganic analytical data, epidemiological models, and environmental sciences to theoretical research in robust statistics, sensitivity analysis, small sample asymptotic techniques, and habitat suitability models (Loma Linda University, University of Southern California, University of California, Irvine, California Summer Mathematics Institute, Lockheed Environmental Systems and Technologies Co., Mifflin & Associates, Inc., USGS National Wetlands Research Center). Draugelis-Dale was employed as Statistician at USGS National Wetlands Research Center (1995-2022), where duties included full statistical support and authorship for migratory waterfowl and aquatic animal research, forest ecology, and National Water Quality Assessment programs: (1) research project and manuscript peer review; (2) consultation; (3) experimental design; (4) analyses for a broad range of statistical applications (univariate and multivariate), including ordination and Bayesian methods, Monte Carlo simulations, and time series analyses; (5) data results presentation, interpretation, and documentation; and  (6) authorship of manuscripts, abstracts, posters, and technical or open file reports. Draugelis-Dale has completed extensive continuing education training at the SAS Institute, Inc. in SAS software, and created and developed three (in five parts) self-training, computer programming course manuals in SAS statistical software for workshop training.   

Education and Certifications

  • Ph.D. 1985, M.S. 1981, M.S. 1979, B.S. 1975

    Loma Linda University, CA, University of Southern California, California State University, Los Angeles

    Mathematical Sciences, Bio

Science and Products

Filter Total Items: 18

Juvenile African clawed frogs (Xenopus laevis) express growth, metamorphosis, mortality, gene expression, and metabolic changes when exposed to thiamethoxam and clothianidin

Neonicotinoids (NEO) represent the main class of insecticides currently in use, with thiamethoxam (THX) and clothianidin (CLO) primarily applied agriculturally. With few comprehensive studies having been performed with non-target amphibians, the aim was to investigate potential biomarker responses along an adverse outcome pathway of NEO exposure, whereby data were collected on multiple biological
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Water Resources, Ecosystems, California Water Science Center, New Jersey Water Science Center, Wetland and Aquatic Research Center

Sperm quality biomarkers complement reproductive and endocrine parameters in investigating environmental contaminants in common carp (Cyprinus carpio) from the Lake Mead National Recreation Area

Lake Mead National Recreational Area (LMNRA) serves as critical habitat for several federally listed species and supplies water for municipal, domestic, and agricultural use in the Southwestern U.S. Contaminant sources and concentrations vary among the sub-basins within LMNRA. To investigate whether exposure to environmental contaminants is associated with alterations in male common carp (Cyprinus
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Ecosystems, Columbia Environmental Research Center, Wetland and Aquatic Research Center

An accurate method for measuring triploidy of larval fish spawns

A standard flow cytometric protocol was developed for estimating triploid induction in batches of larval fish. Polyploid induction treatments are not guaranteed to be 100% efficient, thus the ability to quantify the proportion of triploid larvae generated by a particular treatment helps managers to stock high-percentage spawns and researchers to select treatments for efficient triploid induction.
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Ecosystems, Wetland and Aquatic Research Center

Flow cytometric method for measuring chromatin fragmentation in fixed sperm from yellow perch (Perca flavescens)

Declining harvests of yellow perch, Perca flavescens, in urbanized watersheds of Chesapeake Bay have prompted investigations of their reproductive fitness. The purpose of this study was to establish a flow cytometric technique for DNA analysis of fixed samples sent from the field to provide reliable gamete quality measurements. Similar to the sperm chromatin structure assay, measures were made on
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Ecosystems, Contaminant Biology, Environmental Health Program, Wetland and Aquatic Research Center

Assessing reproductive and endocrine parameters in male largescale suckers (Catostomus macrocheilus) along a contaminant gradient in the lower Columbia River, USA

Persistent organochlorine pollutants such as polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p′-DDE), and polybrominated diphenyl ethers (PBDEs) are stable, bioaccumulative, and widely found in the environment, wildlife, and the human population. To explore the hypothesis that reproduction in male fish is associated with environmental exposures in the lower Columbia River (LC
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Ecosystems, Wetland and Aquatic Research Center

Reproductive health of yellow perch Perca flavescens in selected tributaries of the Chesapeake Bay

Reduced recruitment of yellow perch has been noted for a number of years in certain urbanized watersheds (South and Severn Rivers) of the Chesapeake Bay. Other rapidly developing watersheds such as Mattawoman Creek are more recently showing evidence of reduced recruitment of anadromous fishes. In this study, we used a battery of biomarkers to better document the reproductive health of adult yellow
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Ecosystems, Fisheries Program, Eastern Ecological Science Center, Wetland and Aquatic Research Center , Chesapeake Bay Activities

A comparison of litter production in young and old baldcypress (Taxodium distichum L.) stands at Caddo Lake, Texas

Aboveground primary productivity for cypress forests was assessed from measurements of litter production in two age groups and in two hydrological regimes (standing water and free-flowing). Caddo Lake, located in northeast Texas on the Texas-Louisiana border, offered a unique study site since it is dominated by extensive stands composed entirely of Taxodium distichum (L.) Rich, (baldcypress) in di
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Ecosystems, Wetland and Aquatic Research Center

Sperm quality assessments for endangered razorback suckers Xyrauchen texanus

Flow cytometry (FCM) and computer-assisted sperm motion analysis (CASA) methods were developed and validated for use with endangered razorback suckers Xyrauchen texanus collected (n=64) during the 2006 spawning season. Sperm motility could be activated within osmolality ranges noted during milt collections (here 167–343 mOsm/kg). We hypothesized that sperm quality of milt collected into isoosmotic
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Ecosystems, Wetland and Aquatic Research Center

Davis Pond freshwater diversion biomonitoring: Prediversion and postdiversion freshwater fish data

No abstract available.
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Ecosystems, Wetland and Aquatic Research Center

Effects of herbivory and flooding on reforestation of baldcypress (Taxodium distichum [L.]) saplings planted in Caddo Lake, Texas

The effects of herbivory and flooding were examined on survival and growth of planted baldcypress (Taxodium distichum (L.) Rich.) saplings at three sites in Caddo Lake, TX, over a 4-yr period. There were two flood regimes (shallow periodic and deep continuous), where half of the saplings in each flood regime were protected by tree shelters to prevent herbivory. By the end of the first year, over 8
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Ecosystems, Wetland and Aquatic Research Center

Tree growth and mortality during 20 years of managing a Green-Tree Reservoir in Arkansas, USA

Green-Tree Reservoirs (GTR) are bottomland hardwood forests that are flooded during late fall and winter to provide waterfowl habitat. Early reports suggested that increased moisture improved tree growth and mast production; however, recent reports showed reduced vigor and growth. This study examines the effects of 20 years of GTR management practices in the Felsenthal National Wildlife Refuge, Cr
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Ecosystems, Wetland and Aquatic Research Center

Effects of wastewater discharges on endocrine and reproductive function of Western Mosquitofish (Gambusia spp.) and implications for the threatened Santa Ana Sucker (Catostomus santaanae)

The Santa Ana River (SAR) in southern California is impacted by effluents from wastewater treatment plants (WWTP), which are sources of organic wastewater compounds (OWCs) and urban runoff. The Santa Ana River is one of only three river basins supporting native populations of the federally listed Santa Ana sucker (Catostomus santaanae) at the time the fish was included on the list 2000. In 2004 an
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Ecosystems, Columbia Environmental Research Center, Wetland and Aquatic Research Center
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Fig. 1. A flow cytometric histogram of larval Grass Carp cells

A Website Tool for Predicting Triploidy in Larval Fish Spawns

Differentiating diploids from triploids at the earliest life stage possible allows for a more efficient use of resources including production time and rearing space. Thus, a reliable flow cytometric (FCM) method has been developed to discriminate triploids from diploids at the larval stage. In order to help simplify the process of differentiating triploids from diploids, we propose a simple...
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Ecosystems, Invasive Species Program, Wetland and Aquatic Research Center
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A Website Tool for Predicting Triploidy in Larval Fish Spawns

Differentiating diploids from triploids at the earliest life stage possible allows for a more efficient use of resources including production time and rearing space. Thus, a reliable flow cytometric (FCM) method has been developed to discriminate triploids from diploids at the larval stage. In order to help simplify the process of differentiating triploids from diploids, we propose a simple...
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Science and Products