EERD Virtual Lab Tour

Exposure Research

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Exposure Research
EERD Virtual Lab Tour

Questions about the video or transcript should be directed to Bob Graves at graves.bob@epa.gov or at 513-589-7488

The Ecological Exposure Research Division develops ecological indicators that are primarily used in the assessment of aquatic ecosystems, on scales ranging from great rivers, such as the Ohio, to small streams and isolated wetlands.

How do we develop indicators?  We do this in a number of ways.  One approach is to start right here, on a river like this.  We can collect aquatic organisms, water samples, and other data to take back to our lab in Cincinnati, Ohio.

Once our samples are back at the lab, we begin our analyses.  In our chemistry lab, we can analyze water, sediment or even organisms, to figure out what contaminants the water body has been exposed to.  In our taxonomy lab, we can identify the organisms we collected and in our genetics lab, we can examine them at the molecular level to determine whether they are showing signs of exposure to contaminants.

Another approach to indicator development would be to forgo the field work and instead work in an experimental lab setting such as our Experimental Stream Facility or our Aquatic Research Lab.  In either of these two settings, we can conduct experiments in which we control the exposure of aquatic organisms to contaminants.

Over the next few minutes, we will be highlighting our capabilities in ecological exposure research by taking a brief tour around some of our facilities.

Letâ€™s start our tour at the Experimental Stream Facility.  There are two common problems facing ecologists that study water bodies in nature.  First, it is impossible to know exactly what the organisms in a water body have been exposed to, and second, it is difficult to account for the natural variability that occurs between different water bodies.  In the Experimental Stream Facility, we are able to conduct controlled experiments coupled with natural stream variability.

The facility is equipped with eight 12-meter-long artificial stream channels that have continuous flows of river water and a Chemical Dosing System which allows us to precisely control the chemical contaminants going into the stream.  This system allows us to measure the exposure of aquatic organisms to a variety of contaminants at different concentrations.

Each of the eight streams can be custom configured to optimize habitat conditions for algae, invertebrates or fish.  Physical characteristics of the streams can also be manipulated during experiments.  Some of these manipulations include adding cobble to simulate stream substrate, inducing sediment loading, or changing flow rates to simulate rain events.

Fathead minnows are often used in aquatic research and it is no different here.  They one of the organisms we deploy to help us measure exposures to contaminants under these simulated stream conditions.  Some of the ways we measure exposure is by assessing macroinvertebrate and periphyton community functions; measuring the bioaccumulation of chemical stressors such as pharmaceuticals; determining reproductive health; and measuring the levels of certain genes and proteins in the deployed organisms.

Fathead minnows can also be used in studying exposures under more controlled laboratory conditions.

So letâ€™s go now and take a look around our Aquatic Research Facility.  Ours is the only EPA aquatic facility  that is accredited by the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC).  In this facility, we culture and expose fish, invertebrates, and plants to a variety of contaminants at different concentrations using either our static or flow-through systems.  The animals cultured in this facility include fish, such as fathead minnows and zebrafish; freshwater aquatic invertebrates such as water fleas and midges and the Western Corn Rootworm.

For the fathead minnow, we use a flow-through culture system that consists of spawning tanks, adult rearing tanks, and fry tanks.  This system produces an average of 2000 eggs per day, can hold over 5000 juvenile and adults and 3 to 6 thousand larvae.  The fish we culture are used to conduct routine growth and survival tests and to develop new methods for analyzing exposures to contaminants of concern, such as endocrine disrupting compounds, or EDCs.

For zebrafish, we use a static culture system that consists of 24 aquariums capable of holding 3 to 7 hundred zebrafish.  The fish we culture in this system produce embryos and larvae used to analyze the exposures of various zebrafish strains to PCBs.

The rootworm culture system consists of up to 12 cages of adult beetles, each holding 1 thousand to 15 hundred adults, which are capable of producing 5 to 10 thousand eggs per day.  The larvae from this culture unit are used to analyze the exposure of rootworms to genetically modified corn. 
We also culture and expose aquatic invertebrates in this lab.  Aquatic invertebrates are important indicators of aquatic ecosystem health and that is why they are the focus of many of our projects.

So, letâ€™s move now to our taxonomy lab and see what is going on there.

The taxonomy lab has been used over the past few years in support of many projects such as a large river restoration project and a major headwater streams study.

Our taxonomy lab includes 2 facilities; a sample storage room, an algae room, and an invertebrate room.

The algae room is used for phytoplankton and periphyton sample processing and identification.  It includes a spectrophotometer and a fluorometer for analyzing algal pigments like chlorophyll; a microscope for identifying and for measuring the cell densities and bio-volumes of algae; a fume hood for slide preparation and acid digestion; and a muffle furnace, drying ovens, and balances for measuring dry mass.

The invertebrate room is used for sample sorting and identification.  It includes 2 fume hoods for slide preparation; a bench-top ventilation system for working with samples; stations for sorting invertebrate samples; microscope stations for species-level identification; a taxonomic literature reference library; and data entry stations. We also have the capacity to maintain samples for voucher libraries and for historical studies, such as those concerned with mercury contamination over the years.

In EERD, we are interested in not only identifying organisms in these traditional ways, but also in identifying them using newer technologies such as DNA barcoding.

Our Genetics Lab helps facilitate our research in genetics, genomics, proteomics and informatics.  Some of the methods we use in this lab include DNA barcoding, PCR, DNA sequencing, DNA fingerprinting, microsatellite analysis, electrophoresis, and microarray screening.  This lab is equipped with state-of-the-art instruments capable of processing the large numbers of samples needed for population-level and regional assessments.  These instruments include thermal cyclers, robotic liquid handlers, DNA analyzers, a dedicated 2D electrophoresis station, a spot picker, a multi-format image analyzer and an imaging system.  One of the areas of focus for research conducted in the Genetics Lab is invasive species.

Using DNA technologies, we are able to develop methods for early detection and monitoring and the compilation of DNA barcode databases of known invasive species.  Using the principles of population genetics, we are also able to enhance our understanding of invasive species dispersal patterns, thereby better informing risk assessments and management decisions.

Another focus area for our Genetics Lab is real-world exposures.  Because the impact of pesticides on aquatic ecosystems is still not well understood, our Genetics Lab is developing pesticide-specific indicators of exposure.  Using a series of controlled lab experiments we are identifying different RNA sequences and proteins that indicate what pesticides fathead minnows have been exposed to.  We can test whether the indicators we identified in these controlled experiments are useful by testing fathead minnows in the semi-controlled streams back at the Experimental Streams Facility or in field studies.

In order to utilize these molecular indicators though, we must have the ability to verify the presence of pesticides or other contaminants in aquatic environments.  This is done primarily through chemical analysis of collected samples.

So letâ€™s go now to where that all happens, our Chemistry Lab.  We also conduct analytical research on emerging contaminants.  Using a variety of techniques, we are able to analyze water, sediment and fish tissue samples for the presence of organic contaminants, such as pesticides and PCBs, and inorganic contaminants, such as metals and nutrients.

We use a variety of methods to prepare samples for analysis, such as homogenizing tissue samples or by sieving, extracting and evaporating sediment samples.

For analyses of the samples, we also use a variety of methods.  For example, we use Gas Chromatography with Electron Capture detection to analyze for 30 pesticides and 20 PCBs in fish tissue and sediment.  We use Inductively Coupled Plasma Optical Emission Spectrometry for trace metals and a mercury analyzer for mercury.  For nutrients like Nitrogen, we use a segmented flow analyzer.

The results of these analyses allow researchers to characterize the sampleâ€™s source.

In addition to supporting the research conducted by our scientists, the Chemistry Lab is also developing methods for analyzing pharmaceuticals in effluent waters.  Once developed, these methods will allow us to investigate the exposure of aquatic organisms to human prescription pharmaceuticals that may find their way into the nationâ€™s water bodies.

Developing methods to measure real world exposures is critical for the continued success of aquatic ecosystem research.

Thatâ€™s why we also perform research back here where we started, in the field.  Our knowledge and expertise in field ecology enables us to develop and utilize field methods for assessing evidence of exposure in aquatic ecosystems.  Our methods are developed for flowing waters, ranging from tiny headwater streams to the largest rivers, and for wetlands.  These methods include procedures for collecting samples and performing field measurements that can be used to characterize the condition of a variety of aquatic ecosystems.  We examine individual system components or entire systems, using a variety of tools and techniques, such as electrofishing, seining, kick nets, deployed water sensors, geographic information technologies, and spectrometry.  We look at soils, water, physical habitat, bacteria, algae, aquatic plants, invertebrates, amphibians, and fish, all indicators of the health of the waterbody.  Research performed in the field allows us to examine real world and field exposures, measure ecosystem function, and assess the condition of aquatic ecosystems using multi-scale analysis.

The field methods that we develop can be used to examine ecosystems on an individual basis, looking at a particular river, isolated stream or wetland, or to explore the aquatic ecosystems of an entire region.  Our methods are used by states, tribes, basin commissions, EPA regions and program offices, and other federal agencies to determine if aquatic ecosystems under their jurisdiction show evidence of exposure to contaminants.

The research conducted by EERD is crucial to developing ecological indicators that can be used to assess the health of our nationâ€™s aquatic ecosystems and to improving our understanding of the existing and future relationships between man and the environment.

EERD Virtual Lab Tour

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