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The aquatic toxicology laboratory and its research staff at the Colorado Parks and Wildlife provide a number of services supporting the protection of the States aquatic resources. We conduct toxicity studies to measure responses of fish and aquatic invertebrates to pollutants, including heavy metals, ammonia, and endocrine disrupting chemicals. We also conduct research to measure the impacts of chemical spills, or to document recovery of aquatic life after remediation of a polluted site. CPW participates in the Water Quality Control Commission Hearings to assist the Commission in determining water quality standards for Colorado’s lakes and streams. This process includes working closely with the Colorado Department of Health and the Environment, the EPA and other private entities interested in water quality issues. Below we provide a brief description of our facilities and a summary of our ongoing projects.

The Colorado Water Quality Control Commission estimates that over 2080 km of streams in Colorado are impacted by metals. The Colorado Division of Parks and Wildlife Aquatic Toxicology Laboratory has studied the effects of metals on aquatic organisms for over 35 years. Early investigations focused on the effects of metals on salmonids which led to the development of numeric hardness-based metal standards for the protection of aquatic life in Colorado. Colorado is the first state to implement numeric metal standards.

About our Aquatic Toxicology Laboratory:

The laboratory utilizes an onsite well, dechlorinated municipal tap water and water purified by reverse osmosis for toxicology tests. By mixing these waters, toxicity tests can be conducted over a wide range of water quality conditions.
 
Laboratory toxicity tests use continuous flow-through diluters to deliver several different concentrations of toxicants to test organisms.

Larval and juvenile trout are frequently used as test organisms because these species and life stages are very sensitive to the effects of metals. The Colorado Parks and Wildlife is one of the few laboratories that conduct tests using brown trout, which are an important fish species in Colorado headwaters where metal contamination from abandoned mines can impact aquatic communities. Other fish species used as test organisms include rainbow trout, brook trout and Colorado native species such as cutthroat trout, mountain whitefish, mottled sculpin, longnose dace and flathead chub.

Test organisms also include benthic invertebrates that indicate the health of aquatic ecosystems such as mayflies, stoneflies and caddisflies.

Recent Laboratory Studies on Heavy Metals toxicity:

• Toxicity of zinc to Colorado native aquatic species
• Chronic toxicity of ammonia to early life stage rainbow trout
• Acute and chronic toxicity of cadmium to early life stage cutthroat trout and mountain whitefish
• Effects of water hardness on toxicity of cadmium and zinc to early life stage and juvenile brown trout
• Acclimation and deacclimation of brown trout to cadmium, copper, zinc and their mixtures
• Toxicity of zinc to mottled sculpin at different levels of water hardness
• Toxicity of zinc, copper and cadmium to the mayflies Rhithrogena hageni, Baetis tricaudatus, and Drunella doddsi

Temperature studies:

The laboratory has recently conducted studies to investigate the effect of temperature on survival and growth of Rio Grande cutthroat trout and mountain whitefish. Data will be used to help develop and support temperature standards in Colorado.

Field Studies Documenting Recovery of Aquatic Life from Metals Impacts:

In addition to laboratory studies, the toxicology laboratory has been monitoring water quality and the fish community in the upper Arkansas River since 1994. Water samples and fish are sampled from several sites on the Arkansas River and major tributaries. Water samples are analyzed for metals at the laboratory. Fish are captured, counted, weighed, marked with a fluorescent dye, and then released. Remediation of historic mining sites has improved water quality in the upper Arkansas River resulting in dramatic improvement of fish populations.

We are currently exploring how heavy metals pollution interacts with natural variation in streamflow to impact trout populations in several mine-impacted rivers of Colorado, including the Eagle River near Minturn and the Arkansas River near Leadville. Results of this study will be used to explore the utility of using biocriteria to determine protective water quality standards for these rivers.

Great Plains fishes in river basins of eastern Colorado have been declining and many are now listed as threatened or endangered, including the Common Shiner, Brassy Minnow, Arkansas Darter, Stonecat, and others. Learn more about native Plains fishes. Several factors have been identified as contributing to declines of Plains fishes, including altered flow regimes through diversions and impoundments, predation by non-native fish, channelization and simplification of riverbeds, and general loss of habitat. Reduced water quality from increased urbanization and intense agricultural use likely contribute to population declines, however, the impacts of chemical stressors have not been well studied. We are investigating the impacts of two prominent urban and agricultural stressors, ammonia and endocrine disrupting chemicals, on native Plains fish species.

Toxicity Studies:

In 2011-2012, CPW will conduct laboratory toxicity tests to investigate the effects of metals from dietary sources on survival and growth of trout. We are also collaborating with researchers from Colorado State University, University of Colorado, and USGS to specifically address how endocrine disruptors influence mating behavior, sex ratios and gonadal development of several Plains fish species.

Field Studies:

CPW is conducting research to determine effects of urban and agricultural contaminants on Plains fish communities. This effort will include a multivariate analysis of native fish distributions in the South Platte and Arkansas River basins in relation to water quality in those basins.  Results from our research will assist with identifying potential causes for the decline of native fish in Colorado and help with development of management, conservation and recovery plans.

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Colorado Parks and Wildlife Aquatic Research Section Toxicology and Water Quality Research Lab 317 W. Prospect Road, Fort Collins, CO 80526

Nicole K. M. Vieira, Ph.D. Physical Scientist III Water Quality Researcher Nicole.vieira@state.co.us

Steve Brinkman General Professional IV Aquatic Toxicologist Steve.brinkman@state.co.us