Publications

Many microorganisms secrete secondary metabolites with antibiotic properties; however, there is debate whether the secretions evolved as a means to gain a competitive edge or as a chemical signal to coordinate community growth. The objective of this research was to investigate if select antibiotics acted as a weapon or as a chemical signal by exposing communities of aquatic cave bacteria to increa

Diked and drained coastal lowlands rely on hydraulic and protective infrastructure that may not function as designed in areas with relative sea-level rise. The slow and incremental loss of the hydraulic conditions required for a well-drained system make it difficult to identify if and when the flow structures no longer discharge enough water, especially in tidal settings where two-way flows occur

Ecological restoration has potential for contributing to conservation activities for threatened Mojave desert tortoises (Gopherus agassizii) and Joshua trees (Yucca brevifolia, Y. jaegeriana) and their broader ecosystems in the Mojave and western Sonoran deserts. To be effective, restoration actions deployed strategically need to halt and reverse habitat degradation, replenish or enhance resources

Most conventional approaches for assessing liquefaction triggering hazards generally rely on simplified procedures that involve identifying liquefaction susceptible layers and calculating a factor of safety against liquefaction (FSL) in each layer. Such procedures utilize deterministic semi-empirical models for standard penetration test (SPT), cone penetrometer test (CPT), or shear wave velocity (

Seismic-reflection data were collected in the 1980s as part of the Great Lakes International Multidisciplinary Program on Crustal Evolution (GLIMPCE) to investigate the 1.1 Ga Midcontinent Rift System (MRS). GLIMPCE Line C crosses western Lake Superior from north to south shores (Fig. 1 inset). Many previous workers have interpreted the MRS in Line C as an asymmetric central graben filled with 10–

No abstract available.

The large graben-like troughs and smooth plains visible on the surface of Ariel are indicative of a period of high heat flow in the Uranian moon's past. High heat flows on icy moons like Ariel can also enable viscous flow that removes impact crater topography, a process called viscous relaxation. Here we use numerical modeling to investigate the conditions necessary to viscously relax Ariel's larg

Total mercury (THg) was measured in muscle (fillet) and liver tissue of adult smallmouth bass Micropterus dolomieu collected at multiple sites in the Potomac and Susquehanna River drainages within the Chesapeake Bay watershed. Smallmouth bass in these drainages have experienced episodic mortality events, a high prevalence of skin lesions and reproductive endocrine disruption (intersex or testicula

The initial effects from an asteroid impact are generally well characterized and include thermal radiation and blast waves. If the impactor is sufficiently large, either an earthquake or tsunami can also result, depending on whether the impact occurs over land or water. However, the longer-term effects that extend beyond the area initially affected are less well characterized. Because regional ef

A flexible spill program in the federal Columbia River power system increased the total dissolved gas (TDG) water quality standards (i.e., the gas cap) from 120% to 125%. Spill is used to pass juvenile salmon (Oncorhynchus spp.) over dams, but it can generate elevated TDG, and exposed fish can develop gas bubble trauma (GBT) or experience mortality. Juvenile salmon are monitored for GBT through th

In Alaska’s watersheds, climate change is altering the nature and role of the snowpack, defined as snow accumulation that melts in spring. Generally, the amount of precipitation that falls as snow and the length of the snow-cover season both decrease as temperatures exceed 0°C (32°F) more frequently. The impacts of climate change on snowpack vary among watersheds. In southern, coastal parts of Ala

Reliable estimates of the magnitude and frequency of floods are an important part of the framework for hydraulic-structure design and flood-plain management in Georgia, South Carolina, and North Carolina. Annual peak flows measured at U.S. Geological Survey streamgages are used to compute flood‑frequency estimates at those streamgages. However, flood‑frequency estimates also are needed at ungaged