Publications

Seven hundred and nine surface sediment samples, along with deeper sediment samples, were collected from Hebei Province along the coastal section of the Bohai Sea, China, and analyzed for grain size, concentrations of organic carbon (Corg) and heavy metals (Cu, Pb, Zn, Cr, Cd, As, and Hg). Results indicated that the average concentrations in the sediments were 16.1 mg/kg (Cu), 19.4 mg/kg...

Recent evidence suggests wild rice (Zizania palustris), an important resource for migrating waterfowl, is declining in parts of central North America, providing motivation to rigorously quantify the relationship between waterfowl and wild rice. A hierarchical mixed-effects model was applied to data on waterfowl abundance for 16 species, wild rice stem density, and two measures of water...

Brown bullhead (Ameiurus nebulosus) is a commonly used indicator species for tumor surveys at Great Lakes Areas of Concern. The “fish tumors or other deformities” is one of the beneficial use impairments at the Ashtabula River Area of Concern. In May 2016, 150 brown bullhead were collected in the lower Ashtabula River and 150 were collected in the nearby Conneaut Creek as a reference...

Populations of Northern Spotted Owls (Strix occidentalis caurina; hereinafter referred to as Spotted Owl) are declining throughout this subspecies’ geographic range. Evidence indicates that competition with invading populations of Barred Owls (S. varia) has contributed significantly to those declines. A pilot study in California showed that localized removal of Barred Owls coupled with

Natural resource managers who oversee the Nation’s resources require data to support informed decision-making at a variety of spatial and temporal scales that often cross typical jurisdictional boundaries such as states, agency regions, and watersheds. These data come from multiple agencies, programs, and sources, often with their own methods and standards for data collection and...

The arroyo southwestern toad is a specialized and federally endangered amphibian endemic to the coastal plains and mountains of central and southern California and northwestern Baja California. It is largely unknown how long these toads live in natural systems, how their population demographics vary across occupied drainages, and how hydrology affects age structure. We used...

Genetic networks can characterize complex genetic relationships among groups of individuals, which can be used to rank nodes most important to the overall connectivity of the system. Ranking allows scarce resources to be guided toward nodes integral to connectivity. The greater sage-grouse (Centrocercus urophasianus) is a species of conservation concern that breeds on spatially discrete...

As complex and dynamic systems, wetlands offer the opportunity to investigate and incorporate the ecological concept of succession in educational settings. For example, the well-known, classic hydrosere concept is illustrated in numerous ecology and life-science textbooks. In this chapter, the drawbacks of using the hydrosere successional concept are assessed, and two examples of using...

Summarizing historical records of potentially invasive species increases understanding of propagule pressure, spatiotemporal trends, and establishment risk of these species. We compiled records of non-native pythons and boas from the Florida Keys, cross-referenced them to eliminate duplicates, and categorized each record’s credibility. We report on 159 observations of six python and boa...

In this paper, a parasitism-mutualism-predation model is proposed to investigate the dynamics of multi-interactions among cuckoos, crows and cats with stage-structure and maturation time delays on cuckoos and crows. The crows permit the cuckoos to parasitize their nestlings (eggs) on the crow chicks (eggs). In return, the cuckoo nestlings produce a malodorous cloacal secretion to protect...

Variation in body size across populations of brown bears (Ursus arctos) is largely a function of the availability and quality of nutritional resources while plasticity within populations reflects utilized niche width with implications for population resiliency. We assessed skull size, body length, and lean mass of adult female and male brown bears in four Alaskan study areas that...

Survival rate estimates are critical to understanding the dynamics and status of a population, and they are often inferred from samples of the population’s age structure. A recently developed method uses time series of standing age-structure data with information about population growth rate or fecundity to provide explicit maximum likelihood estimators of age-specific survival rates...