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Full-Text Articles in Life Sciences

Effects Of Environmental Estrogens On Reproductive Biology Of The Fathead Minnow , Robert Bruce Bringolf Jan 2002

Effects Of Environmental Estrogens On Reproductive Biology Of The Fathead Minnow , Robert Bruce Bringolf

Retrospective Theses and Dissertations

Since the early 1990s, environmental estrogens have been recognized as an important environmental threat. Wastewater of 10 aerated lagoon treatment facilities in Iowa was evaluated for estrogenic activity using a short-term caged fathead minnow exposure and a plasma vitellogenin (Vtg) assay. Plasma Vtg results indicated that wastewater entering the three-lagoon systems was estrogenic to male fish, but with serial passage through the lagoons, the estrogenic activity decreased to a level that was not sufficient to induce vitellogenesis. Wastewater retention time in the lagoons may have been a key treatment factor.;Feral fathead minnows captured at aerated lagoon wastewater treatment facilities ...


Assessment Of Diet And Consumption Dynamics Of The Adult Piscivorous Fish Community In Spirit Lake, Iowa , Hongsheng Liao Jan 2001

Assessment Of Diet And Consumption Dynamics Of The Adult Piscivorous Fish Community In Spirit Lake, Iowa , Hongsheng Liao

Retrospective Theses and Dissertations

We explored differences among four well-known indices (%W, %O, %N, and %IRI), plus a modified %IRI (%MIRI), examined diet and consumption dynamics of black crappie (Pomoxis nigromaculatus), largemouth bass (Micropterus salmoides), northern pike (Esox lucius ), smallmouth bass (Micropterus dolomieui), walleye (Stizostedion vitreum), and yellow perch (Perca flavescens ) in Spirit Lake, Iowa, in 1995--1997. %W and %MIRI emphasizes importance of large prey taxa, even when relatively rare in diets, whereas %O and %N emphasize small prey common in diets. %IRI yielded intermediate results. Using %IRI, we found that the most important prey taxa overall were yellow perch, Decapoda, and Amphipoda. Largemouth ...


Landscape Ecology Of Mammalian Predators And Its Relationship To Waterfowl Nest Success In The Prairie Pothole Region Of North Dakota , Michael Lee Phillips Jan 2001

Landscape Ecology Of Mammalian Predators And Its Relationship To Waterfowl Nest Success In The Prairie Pothole Region Of North Dakota , Michael Lee Phillips

Retrospective Theses and Dissertations

Mammalian predation is a major cause of mortality of breeding waterfowl in the Prairie Pothole Region. However, little is known about how landscape features influence the ability of predators to find waterfowl nests. I analyzed the habitat selection and movement patterns of radiomarked red fox ( Vulpes vulpes) and striped skunk (Mephitis mephitis) in two 41.4 km2 study areas with contrasting compositions of grassland (planted cover, pastureland and hayland). The study areas included either 10--15% (Low Grassland Composition, LGC) or 40--50% (High Grassland Composition, HGC) grassland. Edges of wetlands surrounded by cropland were consistently selected by fox and skunk on ...


Hydrological Variation Along The Missouri River And Its Effect On The Fish Community , Mark Alan Pegg Jan 2000

Hydrological Variation Along The Missouri River And Its Effect On The Fish Community , Mark Alan Pegg

Retrospective Theses and Dissertations

The Missouri River has been subjected to human alteration for over 150 years and the flow regime is one physical attribute that has drastically changed as a result of alteration. Likewise, using flow characteristics has been identified as a driving variable to describe fish community structure in lotic systems. Therefore, my goal was to assess fish community structure in the Missouri River system in relation to flow. I first used a time series approach to examine daily mean flow data from 10 gauging stations on the Missouri River, and tested for differences associated with human alteration. Daily mean flow over ...


The Influence Of Habitat Features On Grassland Birds Nesting In The Prairie Pothole Region Of North Dakota , David Joseph Horn Jan 2000

The Influence Of Habitat Features On Grassland Birds Nesting In The Prairie Pothole Region Of North Dakota , David Joseph Horn

Retrospective Theses and Dissertations

Results of habitat fragmentation studies on grassland and wetland birds are not consistent. Some studies have found positive relationships among abundance, nest success, field size, and distance to edges, whereas others have found no relationship. One reason for differing results may be the landscape composition in which the study took place. I examined how landscape composition influenced relations among: (1) occurrence and abundance of grassland songbirds and field size, and (2) nest success of ducks, field size, and edges. I also investigated the effects of mowing on grassland songbirds, and how landscape features, such as amount of perennial grassland, and ...


Toxicity Of Chlorpyrifos Adsorbed On Clay And Humic Acid To Larval Walleye , Todd Alan Phillips Jan 2000

Toxicity Of Chlorpyrifos Adsorbed On Clay And Humic Acid To Larval Walleye , Todd Alan Phillips

Retrospective Theses and Dissertations

Agricultural production poses one of the most serious threats to the continued ecological integrity of environmental systems and has been charged as the activity most responsible for loss of fish species in streams. Although all anthropogenic stressors affecting aquatic ecosystems have not been isolated, suspended solids, sediment, and pesticides are believed to be major factors. The objectives of this dissertation were to: (1) evaluate sources of variability in measuring cholinesterase activity, (2) determine the most sensitive life stage of walleye exposed to chlorpyrifos, (3) evaluate the bioavailability of chlorpyrifos adsorbed on humic acid (HA) and Panther Creek (PC) clay to ...


Breeding Birds Of A Large-Scale Tallgrass Prairie Restoration In Iowa: Monitoring Abundance And Frequency Of Occurrence, Liessa Hyde Thomas Jan 1999

Breeding Birds Of A Large-Scale Tallgrass Prairie Restoration In Iowa: Monitoring Abundance And Frequency Of Occurrence, Liessa Hyde Thomas

Retrospective Theses and Dissertations

Little is known about avian response to habitat restoration, particularly for tallgrass prairies. Neal Smith National Wildlife Refuge, established in 1990, is one of the largest tallgrass prairie restorations of its kind, with land acquisition approved at 3504 ha. Point count surveys were conducted at Neal Smith National Wildlife Refuge from mid May through mid July, 1994-1998. Randomly selected points from four vegetation classes: cropland, herbaceous, riparian, and woodland, were surveyed over the five year study period. A total of 91 summer resident bird species were detected, including 8 grassland-specific species and 2 species from the Iowa threatened species list ...


Butterflies In The Highly Fragmented Prairies Of Central Iowa: How The Landscape Affects Population Isolation, Leslie Ries Jan 1998

Butterflies In The Highly Fragmented Prairies Of Central Iowa: How The Landscape Affects Population Isolation, Leslie Ries

Retrospective Theses and Dissertations

Ever since MacArthur and Wilson presented the Theory of Island Biogeography in 1963, there has been considerable concern about the ability of a system of isolated reserves to retain species diversity or viable populations over extended periods of time. Despite this interest, very little is known about how readily individuals move around in their landscape. Edges and corridors have both been targeted as landscape features that may have important consequences for directing movement and thereby affecting isolation. Edges may form a barrier to movement reducing the probability that an individual will leave a patch. For individuals that have left, they ...


The Foraging Behavior Of Anax Junius (Odonata: Aeschnidae) And Its Potential As A Behavioral Endpoint In Pesticide Testing , Sandra Kaye Brewer Jan 1997

The Foraging Behavior Of Anax Junius (Odonata: Aeschnidae) And Its Potential As A Behavioral Endpoint In Pesticide Testing , Sandra Kaye Brewer

Retrospective Theses and Dissertations

I examined the foraging behavior of the green darner dragonfly nymph, Anax junius, to assess the suitability of odonate foraging behavior as a sensitive endpoint for monitoring contaminant exposure. Odonates are potentially excellent organisms for work in biomonitoring programs because: (1) they have complex foraging strategies that tightly couple sensory cues and mechanical responses: (2) their ecology is well-studied: and (3) they are often the dominant invertebrate predator in fishless systems. Thus they have the potential to structure communities through predation;I tested (1) the possibility that nymphs may regulate populations through frequency-dependent foraging and (2) the relationship between head ...


Maternal Expenditure And The Resolution Of Adult-Offspring Conflict In The South American Guanaco , Ronald James Sarno Jan 1997

Maternal Expenditure And The Resolution Of Adult-Offspring Conflict In The South American Guanaco , Ronald James Sarno

Retrospective Theses and Dissertations

I examined patterns of pre-/post-birth maternal expenditure in the polygynous guanaco, Lama guanicoe, in Torres del Paine National Park, Chile from November 1990 to December 1993. Because of presumed greater variance in reproductive success of males of polygynous species, theoreticians have hypothesized that greater energy investment in sons might improve their competitive abilities and lead to increased reproductive success. Thus, it might be adaptive for parent(s) to invest more energy in sons than daughters. The period of parental care in guanacos is also punctuated by an interval of intense adult-offspring conflict. Adult males seasonally defend feeding territories and ...


Relationship Of Landscape Structure To Ring-Necked Pheasant Population Dynamics In Northern Iowa , Richard Albert Schmitz Jan 1997

Relationship Of Landscape Structure To Ring-Necked Pheasant Population Dynamics In Northern Iowa , Richard Albert Schmitz

Retrospective Theses and Dissertations

I studied demographic processes that operate on individual animals as a means to understand the relationship of landscape structure to population size and survival. I applied the idea of risk-sensitivity to habitat selection by examining the demographic effects on an animal population in which individuals select from two habitats that have similar mean values for reproductive output but differ in the variance of reproductive output. I conducted simulations using a source-sink population model to show that population size increased with increased variation in habitat quality. I then looked at how landscape heterogeneity was related to ring-necked pheasant (Phasianus colchicus) demography ...


Factors Affecting Cholinesterase Activity In Aquatic Animals , Sheryl Linn Beauvais Jan 1997

Factors Affecting Cholinesterase Activity In Aquatic Animals , Sheryl Linn Beauvais

Retrospective Theses and Dissertations

Organophosphorus insecticides (OPs) are extensively used throughout the world to control crop pests. OPs are highly toxic to aquatic animals and can enter aquatic systems that drain agricultural watersheds, but assessment of an aquatic system's exposure to OPs is difficult as these compounds are non-persistent. Timing of sample collections and expense of analyses make direct monitoring of these insecticides problematic. A reliable and sensitive indicator of OP exposure and resulting toxic effects is needed to integrate across exposure events. A good candidate for the indicator is inhibition of cholinesterase (ChE) enzymes; OPs cause acute toxicity primarily through inhibition of ...


Behavior And Survival Of Nesting Wild Turkeys In Southern Iowa , Michael Wayne Hubbard Jan 1997

Behavior And Survival Of Nesting Wild Turkeys In Southern Iowa , Michael Wayne Hubbard

Retrospective Theses and Dissertations

I studied the population dynamics of an established flock of eastern wild turkeys (Meleagris gallopavo silvestris) in south-central Iowa. I also evaluated the influence of various field methods and marking techniques on wild turkey growth and survival. I conducted a laboratory experiment to examine the effect of transmitter attachment techniques on the growth of turkey poults. Surgically implanted transmitters affected wing growth less than backpack harnesses and are recommended for attaching transmitters to wild turkey poults. I also conducted an analysis evaluating various estimates of wild turkey poult survival. Survival estimates obtained from the flush count method for poults 0-4 ...


Evaluation Of Factors Affecting Avian Risk From Granular Pesticides , Tamara Rae Stafford Jan 1996

Evaluation Of Factors Affecting Avian Risk From Granular Pesticides , Tamara Rae Stafford

Retrospective Theses and Dissertations

The Environmental Protection Agency evaluates the risk of granular pesticides to birds using an LD50s/ft2-risk index. The index does not include avian response to granular characteristics, pesticide load per granule, or weather conditions, and it assumes that avian risk increases as granule availability increases. Fensulfothion was formulated on granular pesticide carriers to evaluate the effects of carrier type (silica, clay, and corncob), pesticide load per granule (1/2, 1/8, and 1/32 of the LD50), granule color (blue, white, and uncolored), and granule size (large and small) on captive house sparrows (Passer domesticus). In the initial experiments, silica ...


Fish Communities In Small Agricultural Streams Of Iowa: Relationships With Environmental Factors , Shih-Hsiung Liang Jan 1995

Fish Communities In Small Agricultural Streams Of Iowa: Relationships With Environmental Factors , Shih-Hsiung Liang

Retrospective Theses and Dissertations

Fish distribution and composition in small agricultural streams were compared between major river basins (Mississippi and Missouri) and among five subecoregions in the Iowa region of the Western Corn Belt Plains Ecoregion (WCBPE)) using a 1981-1984 state survey database. Additionally, environmental and fish data were collected from April 1992 to October 1993 from five 50-m stream sections in each of 10 streams representing the subecoregions. The associations among watershed, stream habitat, and fish community features were investigated. The 1993 flooding effects on the headwater habitat and fish communities were also explored. Watershed data were derived from maps, remote imagery and ...


Behavior Of Larval Walleye , Phillip Warren Rieger Jan 1995

Behavior Of Larval Walleye , Phillip Warren Rieger

Retrospective Theses and Dissertations

High resolution cinematography was used to observe larval walleye (Stizostedion vitreum) behavior in laboratory aquaria. Observations focused on gas bladder inflation (GBI), first-feeding, and cannibalism. Four discrete phases of developmental behavior were observed: surface suspension (from hatch to 40 TU); a GBI phase (40-100 TU) with constant, rapid anquilliform swimming at the water surface; a first-feeding phase (100-240 TU) with slower, more subcarangiform swimming throughout the water column in search of food; and, a fully exogenous phase (after 240 TU) when the larvae move to the bottom of culture tanks and easily consume sinking feed particles that come within close ...


Evaluation Of Factors Influencing Grit Use By Birds , James Paul Gionfriddo Jan 1994

Evaluation Of Factors Influencing Grit Use By Birds , James Paul Gionfriddo

Retrospective Theses and Dissertations

Avian grit use was investigated by examining the gizzard contents of free-ranging birds and by conducting aviary experiments with captive birds. Free-ranging Iowa House Sparrows (Passer domesticus) were captured, and their gizzard grit was compared by sex, season, and diet. Males and females did not differ in mean grit amounts (overall x = 580 particles) or sizes, (overall x = 0.5 mm). Birds captured during March and August contained more grit than birds captured during September through February (x = 674 vs. 477). Gizzards containing >75% animal material (insects) had more grit than those containing, >75% plant food (x = 681 vs. 531 ...


Structure Of Breeding-Bird Communities On Natural And Restored Iowa Wetlands, Julie Ann Schreiber Jan 1994

Structure Of Breeding-Bird Communities On Natural And Restored Iowa Wetlands, Julie Ann Schreiber

Retrospective Theses and Dissertations

No abstract provided.


Aggressive Vocalizations In Feeding Guanacos, Lama Guanicoe , Bao-Sen Shieh Jan 1993

Aggressive Vocalizations In Feeding Guanacos, Lama Guanicoe , Bao-Sen Shieh

Retrospective Theses and Dissertations

Guanacos (Lama guanicoe) are highly social ungulates which exhibit subtle threat displays and aggressive vocalizations when feeding. Although studies have qualitatively described aggressive vocalizations, the causation and functional significance of aggressive vocalizations in feeding guanacos are poorly understood. In the General Introduction, I review game theory models for aggressive signals in animal conflicts. In Paper 1, I investigate the causation of aggressive vocalizations, namely, individual and contextual variations in a feeding group of guanacos. In Paper 2, I apply the optimal deceit model to the guanaco feeding group and discuss an alternative hypothesis to interpret the functional significance of aggressive ...


The Influence Of Wetland Age On Bird And Aquatic Macroinvertebrate Use Of Restored Iowa Wetlands , Kristin Leigh Vanrees-Siewert Jan 1993

The Influence Of Wetland Age On Bird And Aquatic Macroinvertebrate Use Of Restored Iowa Wetlands , Kristin Leigh Vanrees-Siewert

Retrospective Theses and Dissertations

Restoration of damaged, lost, and fragmented natural ecosystems is a goal of many public and private conservation organizations, and has become an increasing part of natural resource management. Restoration of wetland habitats has received considerable interest due in part to the dramatic loss of wetland habitat (Dahl 1990), regional decline of waterfowl populations, financial incentives for private landowners to restore former wetland basins (Wetlands Reserve Programs, conservation Reserve Program), and heightened public awareness of wetland functions and values. More than 10,000 drained basins in the Prairie Pothole region of the united states have been restored to wetland conditions since ...


Effects Of Cadmium On Juvenile Bluegill (Lepomis Macrochirus) Foraging Behavior And Growth , Michael D. Bryan Jan 1993

Effects Of Cadmium On Juvenile Bluegill (Lepomis Macrochirus) Foraging Behavior And Growth , Michael D. Bryan

Retrospective Theses and Dissertations

Standardized toxicity testing protocols for assessing chemical hazards to aquatic organisms inadequately consider behavioral effects of toxicants; yet, organisms behaving abnormally in the wild experience reduced growth, fitness, and higher mortality. This study determined the effects of cadmium (0, 30, 60, 120, and 240 [mu]g/L) on juvenile bluegill (Lepomis macrochirus) foraging behavior in three 28-d functional response experiments, and one 24-d multi-prey experiment. The study also examined how cadmium-altered behaviors contributed to reduced growth rates. Different sizes of Daphnia magna and D. pulex were used as prey in these experiments. The rate of change (i.e., trends over ...


Analysis Of Fish Communities In Illinois Lakes , Douglas J. Austen Jan 1992

Analysis Of Fish Communities In Illinois Lakes , Douglas J. Austen

Retrospective Theses and Dissertations

Fish community structure and the main environmental factors influencing community structure were studied using a database of fish population surveys and limnological information describing 144 Illinois lakes. Data were collected by Illinois Department of Conservation fisheries biologists in a standardized manner using electrofishing and gill nets. Population survey data were adjusted using equations estimating efficiency of the gears under varying conditions resulting in estimates of biomass and number of fish per hectare;Guild systems were used to describe the communities and to simplify the analysis of fish community data thus allowing for comparison of community structure between lakes of varying ...


Comparative Ecology Of Two South American Foxes, Dusicyon Griseus And D Culpaeus , Warren E. Johnson Jan 1992

Comparative Ecology Of Two South American Foxes, Dusicyon Griseus And D Culpaeus , Warren E. Johnson

Retrospective Theses and Dissertations

Culpeo (Dusicyon culpaeus) and South American grey fox (D. griseus) have comparable ranges, but the factors determining local and geographic distribution are unknown. I first review the best documented cases of sympatry in canids, and discuss the implications this analysis has on canid conservation. I then compare the behavioral ecology of grey and culpeo fox in Torres del Paine National Park, Chile and review hypothetical factors that determine their distribution when sympatric;The number of sympatric canids per area seems to be determined by a combination of biogeographical history, human intervention, and environmental diversity and productivity. Sympatric canid species either ...


Attitudes And Behaviors Of Iowa Farmers Toward Wildlife , James L. Pease Jan 1992

Attitudes And Behaviors Of Iowa Farmers Toward Wildlife , James L. Pease

Retrospective Theses and Dissertations

This research examines the attitudes and behaviors of Iowa farmers toward wildlife. Based on a 1991 statewide mailed survey of 822 farmers, it divides Iowa farmers into "wildlife-oriented" and "non-wildlife-oriented" groups for sampling and analysis. It identifies demographic and personal factors that are correlated with a wildlife orientation. Wildlife-oriented farmers in Iowa tend to be farmers with smaller acreages overall, with smaller gross farm incomes, with fewer acres devoted to row-crops, and with more diverse landscapes that more often include trees, streams, Conservation Reserve Program acres or other non-agricultural land than farmers who are not wildlife-oriented. Wildlife-oriented farmers also engage ...


Survival And Movements Of Pheasant Chicks In Northern Iowa On Differing Agricultural Landscapes, Dean Edward Ewing Jan 1992

Survival And Movements Of Pheasant Chicks In Northern Iowa On Differing Agricultural Landscapes, Dean Edward Ewing

Retrospective Theses and Dissertations

No abstract provided.


Factors Affecting The Trophic State Of Iowa Lakes, Lorin Kent Hatch Jan 1992

Factors Affecting The Trophic State Of Iowa Lakes, Lorin Kent Hatch

Retrospective Theses and Dissertations

No abstract provided.


Histological And Ultrastructural Studies Of Larval And Juvenile Lampsilis (Bivalvia) From The Upper Mississippi River , Becky Ann Lasee Jan 1991

Histological And Ultrastructural Studies Of Larval And Juvenile Lampsilis (Bivalvia) From The Upper Mississippi River , Becky Ann Lasee

Retrospective Theses and Dissertations

Histological and ultrastructural studies describing early life history stages of freshwater unionid bivalves and studies evaluating impacts of chemical contaminants on early growth are lacking. This study examined larval and juvenile shell ultrastructure of Lampsilis ventricosa using scanning electron microscopy (with observations of Pleurobema cordatum), described morphology of internal organs of laboratory-reared L. ventricosa and evaluated effects of cadmium on juvenile survival, growth and development. Postmetamorphic (juvenile) shell was added to peripheral edges of the larval shell. Initial juvenile shell growth was rapid and coincided with shell deposition into larval shell pores. Glochidia metamorphosed while encapsulated on gills of fish ...


A Comparison Of The Bird And Aquatic Macroinvertebrate Communities Between Restored And 'Natural' Iowa Prairie Wetlands , Philip J. Delphey Jan 1991

A Comparison Of The Bird And Aquatic Macroinvertebrate Communities Between Restored And 'Natural' Iowa Prairie Wetlands , Philip J. Delphey

Retrospective Theses and Dissertations

The glaciated prairie region of north-central and northwestern Iowa once contained a 3-million-ha prairie-marsh complex, but since settlement, 95% of the area's wetlands has been lost (Bishop 1981). Wetland loss has also been great elsewhere in the Prairie Pothole Region, contributing to regional declines of breeding populations of ducks (Batt et al. 1989) and other water bird species (U.S. Fish Wildl. Serv. 1987). To recover some of this lost habitat, federal and state agencies, and private organizations have been restoring large numbers of drained basins since the middle 1980's, mostly on private agricultural land (e.g., Madsen ...


Species Richness And Nest Productivity Of Marsh Birds On Restored Prairie Potholes In Northern Iowa , Lisa Marie Hemesath Jan 1991

Species Richness And Nest Productivity Of Marsh Birds On Restored Prairie Potholes In Northern Iowa , Lisa Marie Hemesath

Retrospective Theses and Dissertations

Since the mid 1800s the number of wetlands in Iowa has decreased by 95% (Bishop 1981). Wetland drainage and the conversion of native grasslands into croplands have been primary causes of this loss. Because of this habitat loss, several wetland species have been extirpated from the state, and others have small populations (Weller 1979, Dinsmore 1981). The 1985 Farm Bill and the North American Waterfowl Management Plan provided the stimulus for wetland restoration on many of these drained basins. My objectives were to 1) determine if certain wetland characteristics affected bird colonization on restored wetlands and 2) assess the habitat ...


Demographic Responses Of Raccoons To Varying Exploitation Rates , James J. Hasbrouck Jan 1991

Demographic Responses Of Raccoons To Varying Exploitation Rates , James J. Hasbrouck

Retrospective Theses and Dissertations

The Cox's proportional hazards model indicated higher harvest levels significantly increased mortality of birth-year (BY) raccoons but not of animals ≥1 year old (ABY). Mortality of ABY males was significantly greater than that of ABY females. Hunters had a marginally significant (P = 0.10) effect on harvest mortality of BY raccoons but neither hunters nor trappers contributed significantly to harvest mortality rate of ABY raccoons. Activity and behavior patterns may contribute to greater harvest mortality of BY raccoons and ABY male raccoons;Monte Carlo simulations were done to investigate bias, efficiency and confidence interval coverage of the Kaplan-Meier (KM ...