As part of a hierarchical approach to classifying watersheds and stream habitats based on geomorphic and geologic criteria, we defined ten classes of fluvial and lacustrine habitats at the scale of valley segments. Valley segments are landscape units which encompass surface waters and the adjacent floodplains and hillslopes with which they interact over time frames of thousands of years. They form a large-scale template that constrains the character of aquatic habitat, controls the effects of disturbances in riparian areas, and mediates responses of streams to upland and upstream events. The regional distribution of valley segment types in southwest Oregon reflects bedrock geology and tectonic history of the landscape. Fluvial segment types differ in stream adjacent landforms, slope erosion processes, floodplain and valley morphology, channel slope, riparian vegetation, streambank texture, gravel bar morphology, and pool-forming features. Studies that do not carefully account for inherent differences between valley segment types could fail to detect critical changes in stream habitat caused by human disturbance. Alluvial valley and alluviated canyon segment types, which have extensive floodplains, low channel slopes, abundant woody debris, and ample gravel beds, are of greatest direct importance for salmon and other native fishes. Virtually all alluvial valleys in the study area have been heavily disturbed by logging, agriculture, and residential development. Alluviated canyon segments located in the few drainage basins where human activity has been limited probably serve as habitat refugia for the last diverse assemblages and productive populations of salmon in the region. Alluviated canyons in extensively-fogged basins exhibit increased abundance of large woody debris, fewer cross-channel debris jams, more extensive bank erosion, reduced pool area and increased riffle area, shallower riffles, and increased surface concentration of fine sediments in pools and other habitats, compared to similar segments in lesser-disturbed basins. These changes in channel morphology and stability appear to be driven by increased sediment load, caused by logging-related landslides and other erosion sources. Field studies in Sixes River basin indicated that abundance and diversity of salmonid fishes declines as maximum stream temperature increases. Changes in summer distribution of juvenile chinook and coho salmon since 1970 are related to changes In water temperature. Although some tributaries have cooled, a decline in rearing distribution in mainstem areas could be caused by long-term loss of channel complexity and associated coolwater refugia. Analysis of fish habitat structures constructed by federal and state agencies indicated that failure rates are high. Recovery of anadromous fish runs in southwest Oregon will require protection of remaining habitat refugia and reduction of sediment yield from disturbed watersheds. / Graduation date: 1992

No description available.

No description available.

This thesis demonstrates how tidal changes in the availability of intertidal zone habitats can affect the distribution and behaviour of juvenile pollock (Pollachius virens). Schools of pollock moved from the subtidal zone to the open habitat in the intertidal zone. On rising tides, pollock switched from the open habitat at low tidal stages to the dense algal habitat at high tidal stages. On falling tides, pollock rapidly schooled downshore in the open habitat. Pollock were rarely solitary in the open habitat and usually formed large schools. In the algal habitats, pollock were usually dispersed and preferred the dense algae over the sparse algae. Predation risk from birds was widely distributed among depths, habitats and stages of the tide, during the day. In a mesocosm experiment, pollock increased their use of the algal habitat and were more difficult to detect following a simulated bird predator threat. Preference for the algal habitat was density-dependent when either pollock abundance or algal habitat area were manipulated. Pollock responded to their potentially high density in the algae by schooling in the open habitat.

In the Canadian prairies, native grasslands have been largely replaced by an agricultural landscape with a mosaic of habitats now better described as aspen parkland. Although habitat requirements of true prairie Buteo species, Swainson's (Buteo swainsoni) and ferruginous hawks (B. regalis), are relatively well identified, little is known about habitat use by red-tailed hawks (B. jamaicensis ) in this ecoregion. This study, evaluating productivity and habitat selection of red-tailed hawks breeding in aspen parkland, was conducted on Prairie Habitat Joint Venture (PHJV) assessment sites in central Saskatchewan in 1997 and 1998. Red-tailed hawk nesting densities and productivity were determined at three sites. Home ranges were mapped. Macrohabitat use and availability data were generated from digitized aerial photographs of PHJV assessment sites using a Geographic Information system. Microhabitat variables were measured in 0.04 ha plots centered on nests and random locations. (Abstract shortened by UMI.)

Dissertação (mestrado)—Universidade de Brasília, Departamento de Ecologia, 2013 / Submitted by Alaíde Gonçalves dos Santos (alaide@unb.br) on 2013-08-09T15:16:30Z No. of bitstreams: 1 2013_DanilodeSiqueiraFortunato.pdf: 2055165 bytes, checksum: c9c7e0bc071f9582bb9e703770e6477f (MD5) / Approved for entry into archive by Guimaraes Jacqueline(jacqueline.guimaraes@bce.unb.br) on 2013-08-09T16:06:03Z (GMT) No. of bitstreams: 1 2013_DanilodeSiqueiraFortunato.pdf: 2055165 bytes, checksum: c9c7e0bc071f9582bb9e703770e6477f (MD5) / Made available in DSpace on 2013-08-09T16:06:03Z (GMT). No. of bitstreams: 1 2013_DanilodeSiqueiraFortunato.pdf: 2055165 bytes, checksum: c9c7e0bc071f9582bb9e703770e6477f (MD5) / A hipótese de diversidade-complexidade de habitat propõe que habitats mais complexos são mais ricos em espécies. A hipótese de diversidade-heterogeneidade propõe que habitats mais heterogêneos são mais diversos por apresentarem maior diversidade de tipos de habitats os quais espécies diferentes podem ocupar. O Cerrado é um ambiente ideal para testar as duas hipóteses, pois apresenta uma grande variação na complexidade da estrutura do habitat, com vegetações campestres a florestais, e predomínio de formações savânicas de Cerrado sensu stricto. A grande variação da estrutura das formações vegetais e a grande diversidade de fatores que determinam sua distribuição fazem com que a vegetação do Cerrado forme um mosaico de grande heterogeneidade. Recentemente, a heterogeneidade natural do Cerrado tem recebido maior atenção e muitos pesquisadores tem afirmado que a diversidade de espécies do Cerrado é resultado de sua alta diversidade beta, que estaria relacionada à heterogeneidade das fitofisionomias do bioma. Assim, compreender como a diversidade de espécies é estruturada em relação à complexidade e à heterogeneidade dos habitats do Cerrado é um passo fundamental para entender os padrões de diversidade de espécies no bioma. Para isso, analisamos como a complexidade de habitats no gradiente vegetacional de Floresta (Mata de Galeria) a Savanas abertas (Cerrado Ralo) dos pontos amostrais influencia a abundância e a diversidade α de espécies de morcegos Phyllostomidae, e como a heterogeneidade resultante do mosaico de fitofisionomia do Cerrado influencia a diversidade β ao longo do mesmo gradiente. Nossos resultados mostram que não existe uma relação da abundância e da diversidade α de espécies de morcegos com a complexidade dos habitas no gradiente estudado. A diversidade β foi relacionada à heterogeneidade resultante das diferenças na estrutura da vegetação ao longo do gradiente. Além disso, diversidade β entre fitofisionomias foi a que mais influenciou a diversidade total da comunidade de morcegos Phyllostomidae no Parque Nacional de Brasília. Encontramos uma relação entre a composição de espécies com a estrutura da vegetação nos pontos amostrais, indicando que as espécies tem algum grau de especialização a alguma parte do gradiente, e que as espécies dominantes como Artibeus lituratus e Carollia perspicillata não apresentam especialização à estrutura do habitat, como esperado. Assim concluímos que a diversidade de morcegos no Cerrado é resultante de diversidade de habitats e que as áreas abertas do bioma são igualmente importantes para a diversidade total quanto as áreas florestais. _______________________________________________________________________________________ ABSTRACT / The hypothesis of diversity-habitat complexity suggests that more complex habitats are richer in species. The diversity-heterogeneity hypothesis proposes that more heterogeneous habitats are more diverse because they present a greater diversity of habitat types in which different species can occupy. The Cerrado is an ideal environment to test the two hypotheses because it presents a wide variation in the complexity of habitat structure, with grassland vegetation to forest, and savanna formations with predominance of Cerrado sensu stricto. The wide variation in the structure of the vegetation and the great diversity of factors that determine their distribution, make that the Cerrado vegetation forms a mosaic of large heterogeneity. Recently, the heterogeneity of the natural Cerrado has received more attention and many researchers have claimed that species diversity of the Cerrado is the result of its high beta diversity, that would be related to the heterogeneity of the vegetation types of the biome. Thus, understanding how species diversity is structured in relation to the complexity and heterogeneity of habitats in the Cerrado is a key step to understand the patterns of species diversity in the biome. So, we analyzed how complexity of habitats in a gradient of forest vegetation (gallery forest) to open savannas (Cerrado Ralo) of sample points influences the abundance and α diversity of species Phyllostomidae bats, and how the heterogeneity resulting mosaic of phytophysiognomy in Cerrado influences the β diversity along the same gradient. Our results show that there is no relationship between the abundance and α diversity of bat species with the complexity of the habitats gradient studied. The β diversity was related to the heterogeneity resulting from differences in the structure of vegetation along the gradient. Furthermore, β diversity between vegetation types was the one that most influenced the total diversity of the community of Phyllostomidae bats at “Parque Nacional de Brasília”. We found a relationship between the species composition and vegetation structure in the sampling points, indicating that species has some degree of specialization to some part of the gradient, and that dominant species, as Artibeus lituratus and Carollia perspicillata, don’t have specializations to habitat structure, as expected. Thus we conclude that diversity of bats in the Cerrado is a result of diversity of habitats and that open areas of the biome are equally important to the total diversity as are forest areas.

No description available.

No description available.

The self-sustaining status of Georgian Bay’s trophy muskellunge (Esox masquinongy) fishery is owed in part to the widespread distribution of high quality coastal wetlands used as nursery habitat. The specific wetland features that promote the recruitment of young-of-the-year (YOY) muskellunge in Georgian Bay have not been clearly defined, and without such information, it is unclear to what extent an unprecedented period of sustained low water-levels (c. 1999), and/or shoreline modifications, will continue to degrade the suitability of nursery habitats used by muskellunge throughout Georgian Bay. In this thesis, I use data from two years of intensive sampling in two embayments of northern Georgian Bay to statistically differentiate between wetlands that were found with and without YOY muskellunge. By doing so, I have provided the first quantifiable definition of suitable nursery habitat for muskellunge in Georgian Bay. Muskellunge nurseries have a structurally complex community of submersed aquatic vegetation (SAV; e.g. Potamogeton richardsonii) within the water column (≤ 1-m depth) and a fish community that had abundant suitable prey (e.g. Cypinid species) and a scarcity of early-life predators (e.g. Perca flavescens). Some key aspects of the SAV community were governed by wetland's bathymetry, and this relationship makes it possible to model the effect of changing water-level scenarios on habitat suitability. I translated these results into a management tool for fish management agencies by creating an Index of Nursery Habitat Suitability (INHS) that can be applied to other embayments in Georgian Bay to identify high quality early-life habitats for muskellunge. I developed two INHS models and applied them to an independent dataset from other regions of Georgian Bay, and found them to differentiate between sites that were known to be used by YOY muskellunge and those where YOY were absent. These were also able to track deterioration in habitat quality associated with the recent decade of low water levels. Both INHS models rely on variables based on robust ecological relationships known to favour YOY survivorship that can be readily collected by fish management agencies, and one INHS model does not require detailed information of the aquatic plant community. Both models were also designed to minimize the frequency of false negatives (suitable nursery sites misidentified as unsuitable) and false positives (unsuitable nursery sites misidentified as suitable). These INHS models should become an important tool that will complement harvest regulations to promote this economically and ecologically valuable, self-sustaining muskellunge population in Georgian Bay. / Thesis / Doctor of Philosophy (PhD) / The following Ph.D. describes how a period of sustained low water levels and shoreline modifications in Georgian Bay, Lake Huron, have impacted the coastal wetland habitat used by muskellunge during their early life. To counteract these adverse effects, the thesis provides a definition of the wetland features that promote the survival of young-of-the-year muskellunge in Georgian Bay. Included is a proposed management tool in the form of an Index of Nursery Habitat Suitability (INHS) for muskellunge that can be used to identify high-quality, early-life habitat of muskellunge. Furthermore, the INHS can be used to predict how the quality of this habitat responds to different water-level scenarios and to shoreline modification in Georgian Bay, and to guide rehabilitative efforts of degraded wetland habitat.

Thesis (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: This study tested several hypotheses regarding various aspects of habitat use by Cape clawless otters Aonyx capensis, in various habitats. The hypotheses, namely that A. capensis do not select any prey types, prey sizes or habitat type were tested. Habitat type was investigated at a scale that enabled separating the effects of types of riparian vegetation, geomorphology and anthropogenic influences. Aspects of the resource dispersion hypothesis (RDH) and optimal foraging theory were tested. This was done in both the marine and freshwater environments. The annual and seasonal diets of A. capensis in the Olifants and Eerste Rivers, Western Cape Province, are described. Crabs were found to be the main prey and fish the second most important prey of A. capensis in both the rivers during all seasons. The percentage occurrence of prey of A. capensis in both rivers, showed an increase in the amount of crab in summer and a corresponding decrease in the number of fish eaten. The seasonal fluctuation in crabs and fish found in the spraints (faeces), corresponded with the expected frequencies as determined from trapping. Seven A. capensis were caught in the two rivers and radiotracked between 1993 and 1995. Total home range length varied from 4.9 to 54.1 km and core home range length from 0.2 to 9.8 km. Total area of water used ranged from 4.9 to 1062.5 ha and core area used from 1.1 to 138.9 ha. As predicted using the RDH total home range length was correlated to mean reed bed nearest neighbour distance. The otters were typically active from dawn for 2.6 h and moved a mean of 0.9 km. They were also typically active from sunset for a mean of 2.3 h moving a mean of 1.3 km. They were found to select for areas with boulders and/or reed beds. Aonyx capensis were found to be mainly solitary in all the habitats. The pattern of female home ranges was suggestive of territoriality. The males, however, had overlapping home ranges, both with other males and females. From spraint analysis and direct observations, the seasonal diet and foraging behaviour of A. capensis feeding in the surf zone in False Bay, Western Cape Province, were determined. The most common prey species during all seasons was Cape rock crab Plagusia chabrus. Diversity of prey was lowest in winter, increasing through the seasons from spring to autumn. Foraging behaviour data support the optimal breathing hypothesis, which predicts that both surface and dive times should increase for dives of greater depths. However, diving efficiency did not decrease with increasing depth, nor did percentage time at the surface increase with increasing depth. These results are contrary to the optimal breathing hypothesis. How A. capensis use their habitat in the presence of potential competitors spotted-necked otters Lutra maculicollis and water mongooses Atilax paludinosus was also determined by investigating their trophic overlap during enforced cohabitation in a relatively small range during drought conditions. The analysis of trophic overlap showed that even during enforced cohabitation in a relatively small range during drought conditions, there was separation of diets of A. capensis, L. maculicollis and A. paludinosus. These results and their implications for conservation management are discussed. / AFRIKAANSE OPSOMMING: Hierdie studie het 'n aantal hipoteses oor verskeie aspekte van habitat gebruik deur die Groototter Aonyx capensis, in verskillende habitatte, getoets. Die nul hipotese, nl. dat A. capensis nie vir enige prooitipe, prooigrootte of habitat-tipe selekteer nie, is getoets. Habitat tipe is ondersoek teen 'n skaalgrootte wat dit moontlik gemaak het om die effekte van tipes oewer plantegroei, geomorfologie en antropogeniese invloede van mekaar te skei. Aspekte van die hulpbron verspreiding hipotese (HVH) en optimale kossoek gedrag, is in beide die varswater en seewater omgewing getoets. Die jaarlikse en seiseonale diëte van A. capens~s in die Olifants and Eerste Riviere in die Wes-Kaap Provinsie, word beskryf. Daar is gevind dat krappe die hoof prooi en vis die tweede mees belangrike prooi van A. capensis in beide riviere, gedurende al die seisoene, was. Die persentasie A. capensis prooi teenwoordig in beide riviere het 'n toename in krap getalle in die somer en 'n ooreenstemmende afname in die hoeveelheid vis wat geeet word getoon. Die seisoenale verandering van krap en vis wat in die keutels (mis) voorkom, het ooreengestem met die verwagte frekwensies soos bepaal deur fangste in fuike. Sewe A. capensis is in die twee riviere gevang en tussen 1993 en 1995 d.m.v. radiosenders gevolg. Die totale tuisgebied lengte het van 4.9 tot 54.1 km, en die kern tuisgebied lengte van 0.2 tot 9.8 km, gewissel. Die totale area water wat gebruik is het van 4.9 tot 1062.5 ha, en kerngebiede van 1.1 tot 138.9 ha gewissel. Soos voorspel deur gebruik van die HVH, was die totale tuisgebied lengte gekorreleer met die gemiddelde rietbedding naaste-buurman analise afstand. Die otters was tipies aktief vanaf sonsopkoms vir 2.6 ure en het dan 'n gemiddeld van 0.9 km beweeg. Hulle was ook tipies aktief vanaf sonsondergang vir 'n gemiddeld van 2.3 ure en het dan gemiddeld 1.3 km beweeg. Daar is gevind dat hulle selekteer vir areas met rotse en areas met rietbeddings. Dit is ook gevind dat A. capens~s in alle habitatte hoofsaaklik alleenlopend is. Die wyfies se tuisgebied-patroon het op territorialiteit gedui, terwyl die manlike diere se tuisgebiede oorvleuel het met beide dié van wyfies, en met dié van ander mannetjies. Die seisoenale dieet en kossoekgedrag van A. capensis wat in die brander sone van Valsbaai, Wes-Kaap Provinsie, voed, is deur keutel analise en direkte waarneming bepaal. Die mees algemene prooi spesie gedurende al die seisoene was die Kaapse rotskrap Plagusia chabrus. Prooi diversiteit was die laagste in winter en het toegeneem vanaf lente tot herfs. Kossoekgedrag gegewens ondersteun die optimale asemhalings hipotese, wat voorspel dat beide oppervlak- en duik tye toeneem met dieper duike. Duik effektiwiteit het egter nie afgeneem met toenemende diepte nie, en persentasie tyd op die oppervlakte het ook nie toegeneem met toenemende diepte nie. Dit is dus in teenstelling met die optimale asemhalings hipotese. Hoe A. capensis hul habitat in die teenwoordigheid van potesieele kompiteerders nl. Klein otters Lutra maculicollis, en Water muishonde Atilax paludinosus gebruik, is ook bepaal. Dit is gedoen deur hul trofiese oorvleueling gedurende noodgedwonge saamleef, veroorsaak deur droogte kondisies in 'n relatiewe klein tuisgebied, te ondersoek. Die resultate van die trofiese oorvleueling analise het getoon dat selfs gedurende noodgedwonge saamleef gedurende droogte toestande in 'n relatiewe klein gebied, daar 'n verskil was in die diëte van A. capensis, L. maculicollis and A. paludinosus. Hierdie resultate en hul implikasies vir bewaringsbestuur word bespreek.