Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Ecology and Evolutionary Biology

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 11911 - 11940 of 12812

Full-Text Articles in Entire DC Network

A Survey Of Drench Resistance In Sheep Worms, J R. Edwards, R. Wroth, G. C. De Chaneet, R. B. Besier, J. Karlsson, P. W. Morcombe, D. Roberts, G. Dalton-Morgan Jan 1985

A Survey Of Drench Resistance In Sheep Worms, J R. Edwards, R. Wroth, G. C. De Chaneet, R. B. Besier, J. Karlsson, P. W. Morcombe, D. Roberts, G. Dalton-Morgan

Journal of the Department of Agriculture, Western Australia, Series 4

Sheep worms which are resistant to chemical drenches have been detected with increasing freuency is Western Australia's south-western farming areas between 977 and 1980. These worms have anthelmintic resistance and such genetis resistance puts essential internal parasite control practices at risk.

This prompted veterinarians in the Esperance, Albany, Bunbury, Geraldton and Northam areas to survey farms to determine the prevalence of resistance to drenches and to define those sheep management practices which encourage its development.

This article describes the survey which was conducted to assess the extent of drench resistance, what causes its build-up and how it can be controlled …


Population Trends Of The Loggerhead Shrike (Lanius Ludovicianus) In Arkansas, Fred L. Burnside Jr., William M. Shepherd Jan 1985

Population Trends Of The Loggerhead Shrike (Lanius Ludovicianus) In Arkansas, Fred L. Burnside Jr., William M. Shepherd

Journal of the Arkansas Academy of Science

No abstract provided.


The Green Movement: Implications For Animals, Ronnie Z. Hawkins Jan 1985

The Green Movement: Implications For Animals, Ronnie Z. Hawkins

Environment Collection

The Green movement, a newly emerging political movement that is both global in scope and firmly anchored to each local region at the grassroots level, is destined to be of great import to those concerned with the status of nonhuman animals in our society. Closely allied with deep ecology and bioregionalism, Green thinking embodies an alteration in our perception of the human organism: no longer seen as separate from and superior to all the other components of the ecosystem, our species is placed in context as one among many interdependent forms of life, with the attainment of a sustainable balance …


Mammals, Birds, And Butterflies At Sodium Sources In Northern Ontario Forests, D. Fraser Jan 1985

Mammals, Birds, And Butterflies At Sodium Sources In Northern Ontario Forests, D. Fraser

Feeding Behavior Collection

Wildlife seen at natural sodium-rich springs and at roadside pools contaminated by highway de-icing salt in northern Ontario included two species of wild ungulates, one species of rodent, three species of birds, and two species of butterflies. The three birds were finches of the sub-family Carduelinae, noted for feeding almost exclusively on plant material. The mammalian species were also herbivorous. Apart from Porcupines (Erethizon dorsaturn), small mammals were rarely seen at the saltwater locations, perhaps because of their apparent preference to ingest salt in solid form rather than in water.


Biotic Interactions Among Estuarine Infaunal Opportunistic Species, Roman Zajac, R. B. Whitlatch Jan 1985

Biotic Interactions Among Estuarine Infaunal Opportunistic Species, Roman Zajac, R. B. Whitlatch

Biology and Environmental Science Faculty Publications

Biotic interactions among soft-sediment infauna were investigated in a small New England estuary in order to determine what effect(s) established opportunistic species had on subsequent recolonization. Interactions were defined according to successional models developed by Connell and Slatyer (1977), e.g. facilitation, tolerance and inhibition. Adults of the opportunistic polychaetes Streblospio benedicti, Polydora ligni and Hobsonia florida were added at 2 densities to separate cores containing defaunated sediment. These cores and control cores containing no worms were sampled at 10 d intervals for 40 d. Cores containing capillary tubes to simulate polychaete tubes were also deployed and sampled at 10 d …


Gametogenesis En Chthonerpeton Indistinctum (Gymnophiona: Typhlonectidae), Rafael O. De Sá, Nibia Berois Jan 1985

Gametogenesis En Chthonerpeton Indistinctum (Gymnophiona: Typhlonectidae), Rafael O. De Sá, Nibia Berois

Biology Faculty Publications

RESUMEN:

Histológicamente, las gónadas de Chthonerpeton indistinctum son similares a las ya descritas para otras especies del orden Gymnophiona. Los lóbulos testiculares se hallan compartimentados en unidades estructurales denominadas lóculos. La espermatogénesis ocurre en cistos sincrónicos de células germinales. Durante la espermiogénesis se identifican cuatro estados consecutivos de desarrollo: 1) cistos de espermátidas redondeadas; 2) cistos de espermátidas arrifionadas; 3) cistos de espermátidas bastoniformes y 4) espermátidas en ramillete.

El análisis histológico de los ovarios mostró la presencia de tres estados en la maduración de los folículos ováricos. Estas etapas pueden ser identificadas de acuerdo a: 1) ubicación del folículo …


Community Ecology, Robert K. Rose, Elmer C. Birney Jan 1985

Community Ecology, Robert K. Rose, Elmer C. Birney

Biological Sciences Faculty Publications

COMMUNITIES with Microtus tend to be structurally simple, usually grasslands or tundra, and to have no more than two species of Microtus and rarely more than six species of small mammals. Microtus often dominates both numerically and in total small mammal biomass, especially at higher latitudes. The small mammal community is most influenced by Microtus through its fluctuations in density, and thus also in biomass, by its relatively high level of diurnal activity, and by its year-round activity. Other species of small mammals may be adversely affected because Microtus usually is larger and behaviorally dominant and also because the mere …


Two Modal Action Patterns With A Continuous Temporal Distribution, Alan B. Bond, George W. Barlow, William Rogers Jan 1985

Two Modal Action Patterns With A Continuous Temporal Distribution, Alan B. Bond, George W. Barlow, William Rogers

Papers in Behavior in Biological Sciences

Most methods of quantitative analysis of animal behavior assume that action patterns can be unambiguously classified into discrete, exclusive categories. This is not invariably the case. The digging behavior of the Midas cichlid (Cichlasoma citrinellum), for example, exhibits two functionally distinct modalities, scoop and pi&, that intergrade continuously in form but are separable probabilistically. We present a technique for analyzing such behaviors that provides a reliable basis for formulating and verifying categories and allows a quantitative assessment of functional dissimilarity.

Die meisten Methoden quantitativer Verhaltensanalysen setzen eindeutige Klassifizierung der Verhaltensweisen in sich wechselseitig ausschlieißende Kategorien voraus. Die sind …


Some Factors Affecting Male Back Space Availability In The Water Bug Belostoma Flumineum Say, Amanda M. Vandenburgh Jan 1985

Some Factors Affecting Male Back Space Availability In The Water Bug Belostoma Flumineum Say, Amanda M. Vandenburgh

Masters Theses

Various factors affecting the availability of male back space in the giant water bug, Belostoma flumineum Say, are described herein and interpreted in a manner consistent with natural selection theory. Newly emerged males are observed to breed and accept eggs sooner than newly emerged females develop an egg clutch: furthermore, newly emerged males were shown to contain motile sperm on the day of adult emergence. Newly emerged females did not contain any mature eggs until approximately six days old. It was also found that newly emerged females manufacture eggs at a linear rate of 4.8 eggs per day. Egg length …


Introduction To Species Of Special Concern In Pennsylvania, Chapter 6--Mammals, Hugh H. Genoways Jan 1985

Introduction To Species Of Special Concern In Pennsylvania, Chapter 6--Mammals, Hugh H. Genoways

University of Nebraska State Museum: Mammalogy Papers

First two paragraphs:

The mammals in Pennsylvania have long been under the management authority of the Pennsylvania Game Commission, but it was not until 1978 that an effort was made to deal with threatened and endangered mammals in the Commonwealth. At this time, Michael J. Puglisi was appointed as Coordinator for the Threatened and Endangered Species Program within the Game Commission. In late February 1979, Mr. Puglisi asked Hugh H. Genoways to chair an informal study group on endangered mammals in Pennsylvania. The immediate concern of this group was to be the development of a list of threatened and endangered …


Age And Growth Of The Bluegill Lepomis Macrochrius Rafinesque From An Unmanaged Watershed Lake In Northeast Arkansas With Observations On Lake Ecology, Stephen A. Sewell Jan 1985

Age And Growth Of The Bluegill Lepomis Macrochrius Rafinesque From An Unmanaged Watershed Lake In Northeast Arkansas With Observations On Lake Ecology, Stephen A. Sewell

Journal of the Arkansas Academy of Science

Age and growth data were compiled on 114 bluegill, Lepomis macrochirus Rafinesque, taken from floodwater retarding structure #15 of the Big Creek Watershed project in Craighead and Greene counties of northeast Arkansas. This project was completed in the early 1960's by USDA-SCS. The 73 surface acre lake has not been managed for fish production and has been subjected to unscheduled water level manipulations during dry weather periods. These manipulations have maintained the bluegill population in healthy condition. The oldest bluegill collected were age class IV+. Average condition coefficient K(TL)declined from oldest to youngest individuals (2.96 in age class IV+ - …


The Ecology Of Foraging Behavior: Implications For Animal Learning And Memory, Alan Kamil, Herbert L. Roitblat Jan 1985

The Ecology Of Foraging Behavior: Implications For Animal Learning And Memory, Alan Kamil, Herbert L. Roitblat

Avian Cognition Papers

In his recent Annual Review of Psychology article, Snowdon (1983) discussed the synthesis of ethology and comparative psychology. A similar synthesis of behavioral ecology and animal learning is beginning to take place. This article reviews developments in the behavioral ecology and ethology of foraging behavior relevant to psychological research on animal learning. The psychological literature shows that animals possess a wide range of learning abilities, including “simple” classical and operant conditioning; they acquire spatial, nonspatial, and temporal discriminations; they exhibit various forms of rule learning (e.g. matching-to-sample and learning set), and may even in certain senses learn language. Why does …


Predation In Insular Plant Dynamics: An Experimental Assessment Of Postdispersal Fruit And Seed Survival, Enewetak Atoll, Marshall Islands, Svata M. Louda, Paul H. Zedler Jan 1985

Predation In Insular Plant Dynamics: An Experimental Assessment Of Postdispersal Fruit And Seed Survival, Enewetak Atoll, Marshall Islands, Svata M. Louda, Paul H. Zedler

Svata M. Louda Publications

We studied predation upon the fruits of four common terrestrial plant species of atolls by excluding: 1) all predators; 2) large predators only; and 3) no predators. Each of these treatments was located within the vegetation at three distances from the shore: beach edge of fringing thicket; middle of the thicket; and inner forest. The plants were Terminalia catappa, Messerschmidia argentea, Scaevola taccada, and Guettarda speciosa. Predation loss over the year was significant (P < 0.01) for all four species. Location contributed significantly only for S. taccada. Amount of loss and predominant type of seed predator for a plant species were related to size and conspicuousness. The largest fruits, …


The Effects Of Prey Depletion On The Patch Choice Of Foraging Blue Jays (Cyanocitta Cristata), Alan Kamil, Sonja I. Yoerg Jan 1985

The Effects Of Prey Depletion On The Patch Choice Of Foraging Blue Jays (Cyanocitta Cristata), Alan Kamil, Sonja I. Yoerg

Papers in Behavior in Biological Sciences

Blue jays (Cyanocitta cristata) were trained to hunt for non-cryptic moths presented in projected images. On each trial, the jays chose one of two patches to hunt in: (1) a uniform, “non-depleting” patch with constant prey density of 0.25; or (2) a “depleting” patch in which prey density changed during the foraging bout. In the depleting patch, the initial prey density was 0.50, declining to zero in a single step part-way through each foraging bout (session). The patch choices of the jays were greatly affected by these conditions. The jays chose the depleting patch early in the session, …


Nearshore Foodwebs And The Distribution Of Acanthocephalan Parasites In Antarctic Seabirds, Eric P. Hoberg Jan 1985

Nearshore Foodwebs And The Distribution Of Acanthocephalan Parasites In Antarctic Seabirds, Eric P. Hoberg

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Field studies, in the vicinity of Palmer Station during the austral summer of 1982— 1983, yielded an extensive collection of acanthocephalans and other parasites from seabirds, fish and invertebrates. The continuing analysis of this material has resulted in the elucidation of factors that control the occurrence of Corynosoma spp. in Antarctic seabirds. Notably, the host-distribution of Corynosoma spp. suggested that these parasites were being acquired from piscine or possibly amphipod prey, generally in nearshore habitats.


Estructura Del Ovario De Chthonerpeton Indistinctum (Reinhardt Y Lutken, 1862) (Amphibia: Gymnophiona) Durante La Gestación, Rafael O. De Sá, Nibia Berois Jan 1985

Estructura Del Ovario De Chthonerpeton Indistinctum (Reinhardt Y Lutken, 1862) (Amphibia: Gymnophiona) Durante La Gestación, Rafael O. De Sá, Nibia Berois

Biology Faculty Publications

La morfología e histología del ovario para varias especies del orden Gymnophiona ha sido reportada por Wake (1968, J. Morphol. 126, 291) y para C. indistinctum por los autores (1984, XXIV Reunión de Comunicaciones, Soc. Zool. Uruguay).

Continuando con los estudios sobre el aparato genital de esta especie vivípara, se presenta ahora la estructura del ovario durante la gestación.

Se procesaron con fines histológicos, ovarios de dos hembras grávidas colectadas en las costas de los Dep. Montevideo y San José en abril, 1983. El número de ejemplares trabajados es muy reducido dado lo difícil que resulta su colecta …


The Prairie Naturalist Volume 16, No. 4. December 1984 Dec 1984

The Prairie Naturalist Volume 16, No. 4. December 1984

The Prairie Naturalist

Paul B. Kannowski, Editor

Nikki R. Seabloom, Assistant Editor

Douglas H. Johnson, Book Review Editor

TABLE OF CONTENTS

VEGETATION PATTERNS IN RELATION TO TOPOGRAPHY AND EDAPHIC VARIATIONS IN NEBRASKA SAND HILLS PRAIRIE ▪ P. W. Barnes, A. T. Harrison and S. P. Heinisch

GREAT BLUE HERON NESTING BIOLOGY ON THE JAMES RIVER IN SOUTH DAKOTA ▪ E. M. Dowd and L. D. Flake

OVENBIRDS AT THE PERIPHERY OF THEIR RANGE IN WESTERN NORTH DAKOTA ▪ R. B. Hopkins

BREEDING BIRD COMMUNITY COLONIZATION OF SOWN STANDS OF NATIVE GRASSES IN NORTH DAKOTA ▪ K. F. Higgins, T. W. Arnold and R. …


A Proposal To Fertilize The Overton Arm And Gregg Basin Areas Of Lake Mead, Larry J. Paulson Nov 1984

A Proposal To Fertilize The Overton Arm And Gregg Basin Areas Of Lake Mead, Larry J. Paulson

Publications (WR)

Several limnological studies have been conducted in Lake Mead during the past decade. The recent studies clearly show that most of Lake Mead is deficient in nutrients, especially phosphorus, and very low in productivity. The reservoir-wide average total phosphorus concentration for 1981 - 1982 was only 9 mg/m3. This is below levels found In most oligotrophic lakes and reservoirs. Algal biomass, as measured by chlorophyll-a, averaged only 1.5 mg/m3. That also places Lake Mead in the oligotrophic range. Transparency, as measured by a Secchi disc, averaged 9-5 m in Lake Mead during 1981-1982. That far exceeds …


Life History Patterns And The Comparative Social Ecology Of Carnivores, Marc Bekoff, Thomas J. Daniels, John L. Gittleman Nov 1984

Life History Patterns And The Comparative Social Ecology Of Carnivores, Marc Bekoff, Thomas J. Daniels, John L. Gittleman

Ethology Collection

No abstract provided.


Demographic Analysis And Microhabitat Relationships Of A Small Mammal Community In Clearings Of The Great Dismal Swamp, Jean Ferguson Stankavich Oct 1984

Demographic Analysis And Microhabitat Relationships Of A Small Mammal Community In Clearings Of The Great Dismal Swamp, Jean Ferguson Stankavich

Biological Sciences Theses & Dissertations

Small mammals were trapped for 14 months on two grids located within a powerline right-of-way in the Great Dismal Swamp National Wildlife Refuge. During 12,354 trap nights, individuals of 10 different species were captured. They included, from highest to lowest density, Reithrodontomys humulis, Ochrotomys nuttalli, Peromyscus leucopus, Blarina brevicauda, Synaptomys cooperi, Microtus pennsylvanicus, Microtus pinetorum, Sigmodon hispidus, Mus musculus and Oryzomys palustris. The demography (densities, reproduction, home range and dispersal) of each species was analyzed when possible. Most of the species were present in relatively low densities, with a number being captured only during the latter months of the study. …


Catalog Of The Recent Scandentia And Primates In The Carnegie Museum Of Natural History, Suzanne B. Mclaren, Duane A. Schlitter, Hugh H. Genoways Sep 1984

Catalog Of The Recent Scandentia And Primates In The Carnegie Museum Of Natural History, Suzanne B. Mclaren, Duane A. Schlitter, Hugh H. Genoways

University of Nebraska State Museum: Mammalogy Papers

The Section of Mammals, Carnegie Museum of Natural History, houses six specimens of Recent tree shrews and 611 specimens of Recent primates. The only family in the Order Scandentia is Tupaiidae. Primate families represented are Lemuridae, Lorisidae, Cebidae, Callitrichidae, Cercopithecidae, Pongidae, and Hominidae. For each specimen the following data are recorded: locality; date collected; catalog number; sex; age; nature of specimen; condition of specimen and comments. The latter category gives information on the condition of the skin and skeletal material, and gives information on the availability of the specimen.


The Prairie Naturalist Volume 16, No. 3. September 1984 Sep 1984

The Prairie Naturalist Volume 16, No. 3. September 1984

The Prairie Naturalist

Paul B. Kannowski, Editor

Nikki R. Seabloom, Assistant Editor

Douglas H. Johnson, Book Review Editor

TABLE OF CONTENTS

GRASSLAND HABITAT MANAGEMENT USING PRESCRIBED BURNING IN WIND CAVE NATIONAL PARK, SOUTH DAKOTA ▪ J. D. Forde, N. F. Sloan and D. A. Shown

BODY TEMPERATURES AND BEHAVIORAL ACTIVITIES OF HIBERNATING

PRAIRIE RATTLESNAKES, Crotalus viridis, IN ARTIFICIAL DENS ▪ K. R. Marion and O. J. Sexton

NEW VASCULAR PLANT RECORDS FOR NORTH DAKOTA ▪ D. T. Disrud, W. T. Barker and R. H. Warner

CHRISTMAS BIRD COUNTS FOR NORTH DAKOTA - 1983 ▪ R. N. Randall

COMPARISON OF PLANKTON POPULATIONS IN THREE …


An Evaluation Of Naturally Occurring Populations Of Magnolia Tripetala L. In Indiana, Kemuel S. Badger Aug 1984

An Evaluation Of Naturally Occurring Populations Of Magnolia Tripetala L. In Indiana, Kemuel S. Badger

All-Inclusive List of Electronic Theses and Dissertations

Magnolia tripetala L. occurs in Indiana as a disjunct from the Appalachian mountains populations. Currently, the known distribution of ~· tripetala in Indiana is confined to seven sites in Crawford County. The current status of ~· tripetala and the surrounding plant community was evaluated to aid in the future study, protection and management of this species, which is endangered in Indiana. Systematic random sampling of the tree stratum was done with belt transects. The sapling and seeding strata were sampled with subplots, placed along the belt transects. Permanent plots were established to enable future monitoring of what is currently prime …


Results Of The Alcoa Foundation-Suriname Expeditions. Ix. Bats Of The Genus Tonatia (Mammalia: Chiroptera) In Suriname, Hugh H. Genoways, Stephen L. Williams Jul 1984

Results Of The Alcoa Foundation-Suriname Expeditions. Ix. Bats Of The Genus Tonatia (Mammalia: Chiroptera) In Suriname, Hugh H. Genoways, Stephen L. Williams

University of Nebraska State Museum: Mammalogy Papers

Five species of Tonatia (bidens, brasilense, carrikeri, schulzi, and silvicola) are known to occur in Suriname. Tonatia bidens and silvicola are the largest in overall size (forearm length over 50 mm and greatest length of skull over 27.0 mm). However, T. bidens has a broader postorbital region (5.0 mm or more) and narrower mastoid region (less than 13.0 mm). The lower incisors of T. bidens are also noticeably broader than those of T. silvicola. These two species were found throughout most of the forested areas of Suriname. T. bidens displayed no secondary sexual …


Activity Levels Of Arboreal Rodents Peromysus And Ochrotomys Evaluated With Nest Cans In Seasonally Flooded Forests, John W. Walke Jul 1984

Activity Levels Of Arboreal Rodents Peromysus And Ochrotomys Evaluated With Nest Cans In Seasonally Flooded Forests, John W. Walke

Biological Sciences Theses & Dissertations

The diversity and density of small mammals in the Dismal Swamp are believed to be small. To test this, four 1.96 ha grids were established and operated in the Dismal Swamp National Wildlife Refuge, from September 1981 to November 1982. Number 10 metal cans covered with plastic lids were placed as nest boxes at 0.5 to 1.5 m height on trees. A 2.5 cm hole allowed access by arboreal rodents, to each nest can. The activity level of the two arboreal rodents, Peromyscus leucopus and Ochrotomys nuttalli, was evaluated by observing types of activity ranging from presence of mice to …


Life History Aspects Of Reithrodontomys Humulis In Southeastern Virginia, Michelle Cawthorn Chandler Jul 1984

Life History Aspects Of Reithrodontomys Humulis In Southeastern Virginia, Michelle Cawthorn Chandler

Biological Sciences Theses & Dissertations

Reithrodontomys humulis, the eastern harvest mouse, is a small cricetid rodent which is common in old field communities in the eastern U.S. A live-trapping study was conducted in Suffolk, Virginia from March 1983 through February 1984 in order to learn the details of its life history and the vegetational characteristics which best describe its microhabitat. Specifically, population densities, trap-revealed survival times, home ranges, plant species composition of the study area, and vegetational structure were examined. In order to trap as many Reithrodontomys as possible, special traps which excluded animals weighing over 20 g were constructed. Densities of harvest mice …


Determinants Of Variation In Avian Mobbing Behavior, Charles Ray Chandler Jr. Jul 1984

Determinants Of Variation In Avian Mobbing Behavior, Charles Ray Chandler Jr.

Biological Sciences Theses & Dissertations

Using three combinations of two experimental stimuli, I initiated mobbing behavior in various species of birds. The objectives of this research were to test the effects of stimuli on mobbing, the predictions of the hypothesis that mobbing functions to drive a predator away, and the effect of other species and individuals on the mobbing behavior of a bird. Mobbing experiments were conducted in a variety of habitats and locations from January 1983 through February 1984.

Only 6.5% of all trials with the mount-only stimulus were successful in attracting birds. Tape-only and mount-and-tape stimuli were equally effective in attracting birds, but …


The Prairie Naturalist Volume 16, No. 2. June 1984 Jun 1984

The Prairie Naturalist Volume 16, No. 2. June 1984

The Prairie Naturalist

Paul B. Kannowski, Editor

Nikki R. Sea bloom , Assistant Editor

Douglas H. Johnson, Book Review Editor

TABLE OF CONTENTS

AUTUMN WEIGHTS OF PLAINS SHARP-TAILED GROUSE IN MONTANA ▪ J. E. Swenson and R. L. Eng

VEGETATION PROFILE AND GRASSLAND BIRD RESPONSE TO SPRING BURNING ▪ G. E. Huber and A. A. Steuter

WETLAND PRESERVATION CONFLICTS IN NORTH DAKOTA: ECONOMIC INCENTIVES AND LANDOWNER ATTITUDES ▪ R. D. Saylor, R. A. Stromstad and M. E. Winger

COLLEMBOLA OF SOUTHWESTERN NORTH DAKOTA: SPECIES COMPOSITION AND HABITAT DISTRIBUTION ▪ B. L. Benner and P. B. Kannowski

NEW RECORDS OF EARTHWORMS FROM KANSAS (Oligochaeta: …


The Hellbender, Cryptobranchus Alleganiensis, In Indiana, William H. Kern Jr. May 1984

The Hellbender, Cryptobranchus Alleganiensis, In Indiana, William H. Kern Jr.

All-Inclusive List of Electronic Theses and Dissertations

Very 1 ittle was previously known ubout the Hellbender, Crrp:t:£branchus alleganiensis alleganiensis, in Indiana. The purpose of this study was to determine its current range and status in Indiana and collect life history information. The hell benders were captured by hand from under rocks and 1d th hoopnets baited with cut fish. They were tagged, measured, wei~hed, examined for large external parasites, wounds, and reproductive cond:i - tion. Stoma ch contents were taken with a non-lethal, stomach-flushfog technique. The animals were then released at the site of capture. Al though they were originally found in the Ohio River, \\'hi tewater …


Seasonal And Spatial Heterogeneity In The Limnetic Zooplankton Community Of Lake Mead, Gene Robert Wilde May 1984

Seasonal And Spatial Heterogeneity In The Limnetic Zooplankton Community Of Lake Mead, Gene Robert Wilde

Publications (WR)

Zooplankton samples collected from throughout Lake Mead, in 1981-1982, demonstrate the presence of a statistically significant seasonal and spatial heterogeneity in zooplankton densities. Seasonally, the major zooplankton groups were most abundant in the spring and fall, coincident with maxima in chlorophyll-a concentrations. Successions among the various rotifers, cladocerans and copepods present in the reservoir were influenced by food availability, diapause, predation by planktivorous fish and, possibly, water temperatures. Spatial heterogeneity in zooplankton densities was unrelated to water temperature, pH, conductivity and dissolved oxygen concentrations, but was related to the abundance of phytoplankton (chlorophyll-a concentrations) and fish. Statistical analyses indicate that …