Publications

Streams are influenced by watershed-scale factors, such as climate, geology, topography, hydrology, and soils, which mostly vary naturally among sites, as well as human factors, agriculture and urban development. Thus, natural factors could complicate assessment of human disturbance. In the present study, we use structural equation modeling and data from the 2008-2009 United States...

Unraveling the effects of climate and land-use on historical fire regimes provides important insights into broader human-fire-climate dynamics, which are necessary for ecologically-based forest management. We developed a spatial human land-use model for Navajo Nation forests across which we sampled a network of tree-ring fire history sites to reflect contrasting historical land-use...

Conservation of at‐risk species is aided by reliable forecasts of the consequences of environmental change and management actions on population viability. Forecasts from conventional population viability analysis (PVA) are made using a two‐step procedure in which parameters are estimated, or elicited from expert opinion, and then plugged into a stochastic population model without...

We examined the genetic structure of the threatened spectacled eider 14–18 years after the initial assessment to evaluate the influence of population recovery on diversity. Concordant with the initial assessment, spectacled eiders were highly structured at mitochondrial (mt) DNA and lacked differentiation at microsatellite loci. The degree and spatial pattern of structure has changed at...

A seminal question in ecotoxicology is the extent to which contaminant exposure evokes prolonged effects on physiological function and fitness. A series of studies were undertaken with American kestrels ingesting environmentally realistic concentrations of the second-generation anticoagulant rodenticide (SGAR) brodifacoum (BROD). Kestrels fed BROD at 0.3, 1.0 or 3.0 µg/g diet wet wt for...

Sesarmid crabs play an important role in organic matter and carbon cycling of mangrove forests. Visual observations and gut content studies have verified that sesarmid crabs are feeding on mangrove leaves, yet stable isotopes of carbon and nitrogen (13C and 15N) have indicated that leaf litter is not assimilated as a food source. Sesarmid crabs tend to be much more enriched in 13C than...

The exotic winter annual grass Bromus tectorum L. (downy brome or cheatgrass) infests millions of hectares of western rangelands. Weed-suppressive bacteria (ACK55 and D7 strains of Pseudomonas fluorescens Migula 1895) have been shown to reduce B. tectorum populations in eastern Washington. Unfortunately, outside of Washington, little is known about the efficacy of these or other weed...

Land use and habitat quality have emerged as critical factors influencing the health, productivity, and survival of honey bee colonies. However, characterization of the mechanistic relationship between differential land-use conditions and ultimate outcomes for honey bee colonies has been elusive. We assessed the physiological health of individual worker honey bees in colonies stationed...

Marine methylmercury concentrations vary geographically and with depth, exposing organisms to different mercury levels in unique habitats. Red-legged kittiwakes (Rissa brevirostris), a specialist predator, forage on fish and invertebrates from the mesopelagic zone, a part of the ocean with elevated methylmercury concentrations. We used kittiwakes as bioindicators of MeHg concentrations...

The Deepwater Horizon (DWH) oil spill from April to July of 2010 contaminated Gulf of Mexico waters through release of an estimated 4.1 × 106 barrels of oil. Beginning in June of 2010, semipermeable membrane devices (SPMDs) were deployed near areas with sensitive marine habitats (Alabama Alps and Western Shelf) potentially exposed to that oil. Elevated TPAH50 concentrations, flux rates...

Kabetogama Lake in Voyageurs National Park, Minnesota, USA suffers from recurring late summer algal blooms that often contain toxin-producing cyanobacteria. Previous research identified the toxin microcystin in blooms, but we wanted to better understand how the algal and cyanobacterial community changed throughout an open water season and how changes in community structure were related...

Wildlife agencies face difficult situations when orphaned or injured American black bear (Ursus americanus ) cubs (