Summer Research Opportunity in Environmental Toxicology:
Harrahy Laboratory
What do we study?
We are interested in the effects of various environmental contaminants on aquatic organisms. Because the “dose makes the poison”, we are also interested in measuring the concentrations and persistence of these contaminants in the aquatic environment. This summer, we will be working on projects related to three types of contaminants: pesticides, pharmaceuticals, and blue-green algal toxins.
In recent years, the number of permits granted by the Wisconsin Department of Natural Resources to treat Eurasian water milfoil and other weeds in lakes with the herbicide 2,4-D has increased. In water, 2,4-D is broken down primarily through the action of microorganisms, and the rate of breakdown increases with increased nutrients, dissolved organic carbon, and temperature. Wisconsin lakes are usually treated with 2,4-D in spring before the target macrophytes have a chance to bloom, or in mid-summer to provide nuisance relief. We are interested in comparing the persistence of 2,4-D in lakes with different levels of organic matter following treatment in spring, when water temperatures are cooler, and microbial activity is expected to be lower. We are also interested in determining the toxicity of 2,4-D to Gammarus sp., an amphipod commonly found in local lakes.
Reports of pharmaceuticals and personal care products (PPCPs) in surface waters have increased in recent years as more researchers have started looking for them, and analytical methods used to detect them have improved. Several studies have linked PPCPs with endocrine disruption in aquatic species. Effects include changes in reproduction, development, growth, and increases in “intersex” condition. Triclocarban is an antimicrobial chemical that has been used for decades in hand soaps and other products. Studies indicate that a good percentage of triclocarban passes through wastewater treatment plants unchanged, and that it is persistent in the environment. Triclocarban was recently shown to act as an endocrine disruptor in rats by enhancing testosterone action, but little is known about the toxicity and potential endocrine disrupting effects of triclocarban in aquatic organisms. We are interested in testing the effects of triclocarban on select aquatic invertebrate species in the laboratory. If time and funds allow, we are also interested in measuring triclocarban and other PPCPs in local wastewater treatment plant effluents and receiving waters.
Blue-green algae (also known as cyanobacteria) are members of the phytoplankton community in many lakes. However, under certain conditions, they can increase in number to form “blooms”, in which scum layers form on the surface of lakes. Blue-green algae blooms are a concern because most species of blue-green algae are capable of producing toxins, including some potent neurotoxins. In Wisconsin, several dogs have died following exposure to blue-green algae in recent years. We are interested in measuring concentrations of blue-green algal toxins, including two that have not previously been measured in Wisconsin: saxitoxin (associated with paralytic shellfish poisoning in marine systems) and BMAA (β-N-methylamino-L-alanine; possibly associated with Alzheimer disease, ALS, and Parkinson disease). Blue-green algae will also be identified and quantified.
What will summer researchers do?
Summer researchers will be involved in both field work and lab work. Field work may include collection of blue-green algae/algal toxin samples, water samples for pesticide analysis, aquatic macroinvertebrates, and various water quality measurements. Lab work may include planning, setting up and monitoring toxicity tests, measurement of algal toxins and pesticides using ELISA (enzyme-linked immunosorbent assay) kits, identification of aquatic macroinvertebrates using a dissecting microscope, and identification of blue-green algae using an inverted microscope. All researchers will also spend some time at the library, working on literature review.
What kinds of skills and knowledge will summer researchers take from this experience?
Researchers will gain knowledge on several current issues in water quality. They will also gain hands-on experience in applying the scientific method and designing experiments while learning the basics of toxicity testing. Other lab work will provide opportunities to increase microscopy skills, while field work will allow researchers to learn sample collection and monitoring skills. Much of what researchers learn could be applied in their own classes (e.g., in a unit on assessing water quality).
Background reading
Carmichael, W.W. 1994. The toxins of cyanobacteria. Scientific American 270(1):78-86.
Halden, R.U. and D.H. Paul. 2005. Co-occurrence of triclocarban and triclosan in U.S.
water resources. Environmental Science and Technology 39:1420-1426.
U.S. EPA. 2005. 2,4-D reregistration eligibility document (RED) facts. EPA-738-F-05-
002.