Thesis (M.S.)--Oregon State University, 1996. / Typescript (photocopy). Includes bibliographical references (leaves 94-100). Also available online.

Once historically widespread throughout the Willamette and Umpqua River drainages, the Willamette Oregon chub is now restricted to scattered populations along 15 miles of the Middle Fork of the Willamette River whereas the Umpqua Oregon chub is still widely distributed. The decline in the Willamette drainage was more severe because changes in the physical and biological habitat were more severe when compared to the Umpqua drainage. The Willamette Oregon chub may be more sensitive to environmental degradations than the Umpqua Oregon chub. The difference in sensitivity to degradation is a result of ecological differences between Willamette and Umpqua Oregon chub. Willamette Oregon chub inhabited areas with primarily very little if any current, fed in the water column, and spawned in aquatic vegetation. Umpqua Oregon chub inhabited areas with primarily slow water velocities, fed on benthic prey, and spawned over gravel substrate. Because Willamette Oregon chub inhabit slackwater habitats they may be more sensitive to water velocity increases and exotic species, whereas Umpqua Oregon chub have a habitat refuge in relatively faster water velocity habitats. Willamette Oregon chub larval stages are described and illustrated. The following combination of characters distinguish Willamette Oregon chub larvae from other cyprinid larvae found in the Willamette drainage: 33-37 myomeres, preanal length of 52-61%, and absence of snout pigment. Willamette Oregon chub larvae generally congregated in nearshore areas, in the upper layers of the water column, in shallow water. They fed primarily in the water column, and ate primarily rotifers and cladocerans. / Graduation date: 1989

Resident bull trout (Salvelinus confluentus) may be particularly vulnerable to human related disturbance, however very few studies have focused on resident bull trout populations. The abundance of bull trout is one measure of the strength and potential for persistence of a population. Habitat characteristics may influence resident bull trout abundance to differing degrees and by varying means at multiple spatial scales. We used day and night snorkel counts to assess relative bull trout abundance. A modification of the Forest Service R1/R4 Fish and Fish Habitat Inventory was used to assess habitat characteristics associated with resident bull trout. Logistic and multiple linear regression were used to assess the relationships between resident bull trout abundance and habitat characteristics at the patch (1 to 5 km), reach (0.5 to 1 km) and habitat unit (1 to 100 m) scales. Site categorical variables were used along with quantitative habitat variables to explain among-site and across-site variation in the data. The significance of both quantitative habitat variables and categorical site variables at various spatial scales suggest that relationships between bull trout abundance and habitat characteristics are complex and in part dependent on scale. The characteristics of individual habitat units explained little of the variation in bull trout presence/absence (logistic regression; Somers' D=0.44) and density (multiple linear regression; adjusted R��=0.08) in habitat units, however there were habitat characteristics that were significantly (P���0.05) correlated to bull trout presence/absence and density in habitat units. The relationships between habitat characteristics and bull trout presence/absence and density varied between habitat unit types. There was a strong quadratic relationship between bull trout abundance and mean summer water temperature at the reach (P=0.004) and patch scales (P=0.001). The mean temperature of patches appears to explain some of the variation in bull trout density at smaller spatial scales, such as reaches and habitat units. An appreciation of the complex nature of scale dependent interactions between bull trout abundance and habitat characteristics may help resource managers make wiser decisions regarding conservation of resident bull trout populations. / Graduation date: 2000

The Roosevelt elk (Cervus elephus roosevelti) is a National Forest management indicator species on the westside of the Cascade mountains, Western Oregon. A Habitat Effectiveness model is used by State and Federal agencies to evaluate elk habitat in the region. Concerns about the model's lack of differentiation between winter and summer ranges in the analyses and assumptions that burning will increase forage quality on winter range prompted this study. I investigated the effect of broadcast burning, plant association, and time since disturbance on the quality of trailing blackberry (Rubus ulna), red huckleberry (Vaccinium parviflorum), willow (Salix spp.), vine maple (Acer circinatum), salal (Gaultheria shallon), and red elderberry (Sambucus racemosa). Crude protein, neutral detergent fiber, acid detergent fiber, acid insoluble ash, lignin, astringency, condensed tannin, and hydrolyzable tannin contents were measured. No significant effects of burning, plant association, or age were observed for crude protein, hydrolyzable tannins, or neutral detergent fiber. Crude protein varied among taxa: trailing blackberry contained 9.65%, and the other taxa ranged from 5.21-7.24%. Neutral detergent fiber was highly variable: trailing blackberry contained 30.90%, and the other taxa ranged from 52.20%-65.06%. Acid detergent fiber content ranged from 44.88%-49.49% for all taxa except trailing blackberry (17.78%). Lignin varied among taxa: trailing blackberry had the lowest content (6.37%) and salal had the highest (30.25%). Lignin content in salal was greater on recently disturbed sites. Astringency ranged from 0.0015 mg protein precipitated per mg plant tissue in vine maple to 0.6737 in trailing blackberry. Salal and willow had intermediate astringencies: elderberry, huckleberry, and vine maple had the lowest. Hydrolyzable tannins were present in all species except red elderberry. Burning and plant association effected astringency and condensed tannin content in trailing blackberry and huckleberry. Samples from burned, very dry and resource-poor sites had higher astringencies than on similar unburned units and non-resource-limiting sites. Condensed tannin contents increased with unit age in salal, huckleberry, and trailing blackberry, possibly accumulating during peak years of re-establishment after disturbance. Vine maple and red huckleberry were the only taxa with positive digestible protein levels. Digestible protein content may be higher in winter forage on less severe sites. Elk forage enhancement in winter range should be evaluated on a site-specific basis. Burning did not promote a detectable increase in quality for these forage taxa, and it decreased the quality of species sensitive to site conditions. / Graduation date: 1991

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.

No description available.

The objective of this study was to determine differences in small mammal assemblage structure and population dynamics among four oak dominated sites at four different stages of gypsy moth disturbance: a high tree mortality site, a disturbance in process site, a disturbance recovery site, and an undisturbed reference site. More specifically, the study was designed to identify changes in habitat structure that would influence small mammal microdistributions and determine the quality of habitat created by gypsy moth herbivory using demographic structure of <i>Peromyscus</i> populations as an indicator of habitat quality. <i>Peromyscus leucopus</i>, Peromyscus maniculatus, the Soricids, and <i>Clethrionomys gapperi</i> had greater abundances at the disturbed sites relative to the reference site. Gypsy moth disturbance increased the abundance of small mammals and the number of coexisting species within a given area, which was attributed to several changes in habitat structure. The disturbed sites were characterized as having more fallen logs and standing dead snags, greater shrub and herbaceous cover, and higher invertebrate abundances relative to the reference site. These changes in habitat structure provided small mammals with increased cover from avian predators, more food resources, and potential nesting cavities. <i>P. leucopus</i> populations at the high mortality site exhibited greater demographic stability than the reference Site populations. This was marked by higher proportions of females, smaller density fluctuations, more fall recruitment of young, higher residency, and lower proportions of males. Strong evidence for density-dependent population regulation was observed for <i>P. leucopus</i> populations at the high mortality site and the <i>P. maniculatus</i> population at the recovery site. At high densities these populations exhibited extensive intraspecific microhabitat segregation. Female adults segregated from juveniles and male adults into more optimal microhabitats. Male adult microhabitat use significantly differed from male juvenile microhabitat use. The exclusion of young mice from optimal microhabitats by adults may be a mechanism by which adults limit over-exploitation of resources by subordinate members of the population at high densities. The results of this study suggest that gypsy moth disturbance of areas dominated by chestnut oaks at least temporarily improves habitat quality for small mammals. / Master of Science

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg 2014 / Polycyclic Aromatic Hydrocarbons (PAHs) are environmental contaminants which are formed during combustion of organic material such as coal, petroleum compounds and meat. Other sources of PAHs include automobile exhaust, coal tar and crude oil. Natural sources of PAHs include volcanoes, forest fires. Some PAHs are known to be carcinogenic and toxic. They are available to aquatic organisms such as fishes through contaminated sediments and other marine organisms. Due to their toxicity, it is essential to study and monitor PAHs in the environment. In this study, the quechers extraction method was developed and optimised for the extraction of 5 PAHs (Naphthalene, acenaphthene, phenanthrene, fluoranthene, and pyrene). The optimised parameters were the extraction speed, extraction time, volume of solvent, type of solvent, the mass of salt (MgSO4), the mass of fish used for extraction, mass of sorbent (PSA) and the type of sorbent used. After optimisation, the optimised QuEChERS extraction method was then compared to the Soxhlet extraction method. Firstly by spiking with different concentration and comparing the recoveries. Recoveries obtained where similar, this shows that the QuEChERS method is efficient for extraction of PAHs. The optimised QuEChERS extraction method and Soxhlet extraction were applied for analysis of PAHs in real fish samples. Fish samples were obtained from two dams, Jericho dam in Mpumalanga and Hartbeespoort dam in Gauteng. The result obtained for both extraction method were compared. The concentration of PAHs obtained for both methods were similar. Naphthalene was not detected in Hartbeespoort dam. The concentration of PAHs in Hartbeespoort and Jericho dam using QuEChERS extraction method range from 0.8 μg/kg to 739 μg/kg and 0.8 μg/kg to 7.4 μg/kg respectively. Acenaphthene and phenanathrene were not detected in all fish sample from Jericho dam, while pyrene was not detected in some of the fish samples from Jericho dam. Application of Soxhlet extraction to real sample gave concentration ranging from 1.9 μg/kg to 908 μg/kg for Hartbeespoort dam and 1.2 μg/kg to 18.7 μg/kg for Jericho dam. High concentration of PAHs was obtained from Hartbeespoort dam.

This study focused on the interactions between small skinks and their major predators/competitors (birds) and prey (arthropods) in core and edge areas of small, long established remnant Cumberland Plain woodlands of Richmond, New South Wales, Australia. Eight study sites were selected (4 edge and 4 core) within the peri-urban environment to compare the abundance and diversity of small skinks, birds and arthropods. Of the three taxa, only arthropods maintained a similar abundance and diversity between edge and core areas. Birds and skinks were either in lower numbers in the perimeter areas (skinks), or were interior/perimeter specialists (birds). Arthropod diversity and abundance of preferred skink prey, was also examined. It was concluded that the distribution of arthropod prey was similar between core and edge areas, and therefore, was not considered to have an influence on small skinks’ ability to inhabit edges. However, large, aggressive/noisy birds (including skink and small bird predators) dominated edge areas. Those birds encountered in the edge foraged in a variety of niches, such as on the ground or they swooped from vantage points. This, coupled with other anti competitor behaviour (e.g. noise, aggression, flocking), placed these birds in proximity to skinks in the edge areas. However, as most of these birds were also predators of skinks, it was concluded that the evidence supported a predator/prey relationship in the perimeter area, rather than a competitive one. This was supported by predation rates on skinks, using decoys. Birds preyed on small skink in greater numbers in the perimeter of woodland remnants than in their interior. This predation pressure was sustained throughout the year. It was concluded that predation and/or displacement of skinks and small birds resulted in lower numbers being observed in edge compared to core areas. This study demonstrated that old, small remnants not continually exposed to major disturbances (e.g. logging, agricultural practices) can re-establish stability in terms of environmental conditions. However, a stable environment or a single taxonomic group does not necessarily predict the response individual taxa will have to edge habitats and that this can alter the interactions between dependent groups such as prey/predator or competitors. . / Doctor of Philosophy (PhD)

Effects of 4-inch (10.16 cm) suction dredge mining on benthic macroinvertebrates in 3rd to 4th order streams were investigated in 1996 by evaluating four mining claim operations in Althouse Creek, Sucker Creek, and Taylor Creek in southwestern Oregon's Rogue River basin. The effects were site-specific. The study showed no significant (p>0.05) differences between treatment and control areas in density and species diversity of benthic macroinvertebrates. However, mean taxa richness significantly (p<0.05) increased thirty days following the end of the mining period. Collector-filterers were significantly (p<0.05) lower in dredged areas thirty days after the mining season. Because of constraints in sampling design, sample sizes and relatively small treatment areas, the results from this study are tenuous at best. There were apparent inherent differences in species dominance among sites possibly a result of differences in stream size and riparian conditions. This further confounds results of this study. / Graduation date: 2000