Publications

New U–Pb zircon geochronology identifies a latest Triassic (ca 214–201 Ma) igneous suite of tuff, hypabyssal dikes, and a pluton on the southern Kenai Peninsula, Alaska. The igneous suite was emplaced within Upper Triassic sedimentary rocks along the southern margin of Western Wrangellia, the western-most fragment of the Wrangellia composite terrane. The igneous rocks range from mafic...

Urban runoff from streets and parking lots carries pollutants that degrade receiving waters. Green infrastructure, such as biofilters, is increasingly used to treat this runoff by mimicking natural hydrologic processes. The U.S. Geological Survey, in cooperation with the Milwaukee Metropolitan Sewerage District, evaluated a biofilter receiving roadway runoff from an industrial area in...

Streams and rivers in urban watersheds are predicted to export more bioreactive, autochthonous dissolved organic matter (DOM) relative to forested watersheds. However, the spatial and temporal variations of DOM quality in forested urban watersheds remain uncertain, and their relationships with socioeconomic conditions, biological characteristics, and the built environment are...

The United States Geological Survey (USGS) provides scientific information for the Department of Interior and the nation, consistent with its original mission expressed in the Organic Act of 1879 (43 U.S.C. 31): “the classification of the public lands and examination of the geological structure, mineral resources, and products within and outside the national domain.” Legislation such as...

Population assessments can be used to determine species' viability and inform conservation efforts; however, obtaining sufficient data quality and quantity can be challenging when monitoring resources are scarce. Brook Floater (Alasmidonta varicosa) is a freshwater mussel that is state listed in the United States as endangered or threatened in 10 of the 14 states it occupies. Despite the

Isotope values in fish eye lenses may be useful in differentiating rearing origins. We compared eye lens isotopic values of fall fingerling age-0 walleye (Sander vitreus) reared in a hatchery pond, a recirculating aquaculture system (RAS), and a natural lake. Using 10 fish per rearing source, we delaminated layers from one eye lens per fish to assess temporal changes in carbon (δ13C) and...

Lakes are vital ecosystems in southwest Alaska, supporting Pacific salmon, wildlife, and people. In Katmai and Lake Clark National Parks and Preserves, lakes span diverse landscapes containing volcanic uplands, glacier-fed valleys, and tundra all of which combine to influence their temperature, water quality, and ability to support critical uses. As the regional climate shifts, our...

Field assessments and laboratory studies have demonstrated that mayflies (Ephemeroptera) are relatively sensitive to increased concentrations of major geochemical ions (Na+, Ca2+, Mg2+, K+, Cl−, SO42−, HCO3−/CO32-), but much remains to be learned about potential mechanisms of toxicity. In the present study, we sought to determine whether solution osmolarity is sufficient to predict the...

Phytoplankton are essential primary producers in fresh surface water that are critical to the health of ecosystems. However, phytoplankton overgrowth due to eutrophication threatens ecological, economic, and public health. Therefore, assessing phytoplankton is fundamental for understanding the productivity, health, and trophic status of freshwater ecosystems. Light microscopy and...

The Florida River in southwestern Colorado, USA, flows through the Southern Ute Reservation and is a cultural and water resource to Tribal and non-Tribal communities. High concentrations of total Al, up to 16 400 µg l–1, have been detected in the Florida River. Elevated Al concentrations in water may affect aquatic organisms’ ability to regulate ions and inhibit respiratory functions...