Digital Commons Network^™

Organochlorine Pesticides In Chlorioallantoic Membranes Of Morelet's Crocodile Eggs From Belize, Christopher B. Pepper, Thomas R. Rainwater, Steven G. Platt, Jennifer A. Dever, Todd A. Anderson, Scott T. Mcmurry

Biology Faculty Publications

Recent studies examined the utility of the chorioallantoic membrane (CAM) as a nonlethal, noninvasive indicator of environmental contaminant exposure in oviparous wildlife. The CAM is a highly vascularized extraembryonic membrane that functions as a site for respiration, nutrient transport, and waste storage during embryonic development. After hatching, the CAM is usually discarded with the eggshell and can be used for chemical residue analysis. Chorioallantoic membranes have been used successfully to examine contaminant exposure and predict chemical concentrations in multiple species of birds and reptiles. In this study, we examined organochlorine (OC) pesticide concentrations in CAMs from eggs of Morelet's crocodiles …

Endocrine-Disrupting Effects Of Cattle Feedlot Effluent On An Aquatic Sentinel Species, The Fathead Minnow, Edward Orlando, Alan Kolok, Gerry Binzcick, Jennifer Gates, Megan Horton, Christy Lambright, L. Earl Gray Jr., Ana M. Soto, Louis J. Guilette

Biology Faculty Publications

Over the last decade, research has examined the endocrine-disrupting action of various environmental pollutants, including hormones, pharmaceuticals, and surfactants, in sewage treatment plant effluent. Responding to the growth of concentrated animal feeding operations (CAFOs) and the pollutants present in their wastewater (e.g., nutrients, pharmaceuticals, and hormones), the U.S. Environmental Protection Agency developed a new rule that tightens the regulation of CAFOs. In this study, we collected wild fathead minnows (Pimephales promelas) exposed to feedlot effluent (FLE) and observed significant alterations in their reproductive biology. Male fish were demasculinized (having lower testicular testosterone synthesis, altered head morphometrics, and smaller …

Diet Quality And Food Limitation Affect The Dynamics Of Body Composition And Digestive Organs In A Migratory Songbird (Zonotrichia Albicollis), Barbara J. Pierce, Scott R. Mcwilliams

Biology Faculty Publications

Migrating songbirds interrupt their feeding to fly between stopover sites that may vary appreciably in diet quality. We studied the effects of fasting and food restriction on body composition and digestive organs in a migratory songbird and how these effects interacted with diet quality to influence the rate of recovery of nutrient reserves. Food limitation caused whitethroated sparrows to reduce both lean and fat reserves, with about 20% of the decline in lean mass represented by a decline in stomach, small intestine, and liver. During refeeding on diets similar in nutrient composition to either grain or fruit, foodlimited grain-fed birds …

The Effect Of Size-Limited Brood Capacity On Brood Size In A Freshwater Bivalve, Mark Beekey

Biology Faculty Publications

Size limited brood capacity is common among species with hard exoskeletons or shells. In these species, brood size is limited by the physical capacity to hold offspring. Here we present evidence that brood size is limited by physical constraints in Sphaerium striatinum , a small brooding bivalve. Sphaerium striatinum is a sequential brooder and produces offspring throughout the year. Offspring are brooded in marsupial sacs located on the inner demibranch. In an unconstrained brooder one would predict that brood size would increase as a function of adult length cubed, a volumetric relationship. In S. striatinum, brood size increases as less …

Two-Phase Species-Time Relationships In North American Land Birds, Ethan P. White

Biology Faculty Publications

The species-time relationship (STR) is a macroecological pattern describing the increase in the observed species richness with the length of time censused. Understanding STRs is important for understanding the ecological processes underlying temporal turnover and species richness. However, accurate characterization of the STR has been hampered by the influence of sampling. I analyzed species-time relationships for 521 breeding bird survey communities. I used a model of sampling effects to demonstrate that the increase in richness was not due exclusively to sampling. I estimated the time scale at which ecological processes became dominant over sampling effects using a two-phase model combining …

Hydrologic Variability, Organic Matter Supply, Anddenitrification In The Garonne River Ecosystem, Michelle A. Baker, P. Vervier

Biology Faculty Publications

1. Groundwater nitrate contamination has become a worldwide problem as increasing amounts of nitrogen fertilisers are used in agriculture. Alluvial groundwater is uniquely juxtaposed between soils and streams. Hydrological connections among these subsystems regulate nutrient cycling.

2. We measured denitrification using an in situ acetylene‐block assay in a nitrate‐contaminated portion of the Garonne River catchment along a gradient of surface water–ground water mixing during high (snowmelt) and low flow.

3. During high flow (mid‐April to early June) the water table rose an average of 35 cm and river water penetrated the subsurface to a great extent in monitoring wells. Denitrification …

Reproduction And Seasonal Activity Of Silver-Haired Bats In Western Nebraska, Keith Geluso, Jeffrey J. Huebschman, Jeremy A. White, Michael A. Bogen

Biology Faculty Publications

Silver-haired bats (Lasionycteris noctivagans) were thought only to migrate through Nebraska; however, recent surveys in eastern Nebraska report summer records of females and their young. Our study in western Nebraska also shows that silver-haired bats are summer residents. We discovered the 1st reproductively active L. noctivagans in this part of the state. We caught lactating females and volant young in riparian forests along the North Platte River and in forested areas of the Pine Ridge. Previously, adult males were not known from Nebraska in summer, and only 4 records of L. noctivagans were known from western Nebraska during …

Grassland Diversity And Productivity: The Interplay Of Resource Availability And Propagule Pools, Bryan L. Foster, Timothy L. Dickson

Biology Faculty Publications

Processes operating at multiple spatial scales govern the structure and functioning of ecological communities. We conducted a resource manipulation and propagule addition experiment in grassland to evaluate the interaction of local resource availability and propagule pools in governing local-scale plant colonization, biodiversity, and above-ground productivity. The availabilities of establishment microsites and water were manipulated in field plots for two years through the application of experimental soil disturbances and irrigation, respectively. Resource manipulations led to increased invasibility of the community, as predicted by the theory of fluctuating resources. Rates of colonization,enhanced by the sowing of 32 grassland species, increased plant diversity …

Seasonal Activity And Reproduction In Bats Of East-Central Nebraska, Kenneth N. Geluso, Russell A. Benedict, Francis L. Kock

Biology Faculty Publications

Information on seasonal activity and reproduction is presented for seven species of bats inhabiting east-central Nebraska (Eptesicus fuscus, Myotis septentrionalis, Nycticeius humeralis, Lasionycteris noctivagans, Lasiurus borealis, L. cinereus, and Pipistrellus subflavus). Early and late dates of capture show five species active in the state for longer periods than previously reported. During some years, E. fuscus and M. septentrionalis emerge from winter torpor in March and feed on insects. Some E. fuscus inhabiting a floodplain forest in summer use houses in nearby towns as hibernacula, and year-round use of buildings by E. fuscus is substantial compared to other species of bats. …