Thesis (M.S.)--Montana State University--Bozeman, 2004. / Typescript. Chairperson, Graduate Committee: Clayton B. Marlow. Includes bibliographical references (p. 49-53).

No description available.

No description available.

M.S.

The goal of this research was to formulate new tools for instream-flow analyses, with emphasis on protecting fish assemblages in speciose, warmer-water streams. This included habitat and fish data sets for the upper Roanoke River (URR) in southwestern Virginia, collected during the warmer, low- f low seasons of 1989-1991. Physical data were collected in small, rectangular quadrats or crosssectional transacts, whereas fish were collected by seining and electroshocking in the quadrats. Statistical analyses included uni-, bi-, and multivariate analyses. The habitat analyses showed that mesohabitat types could be effectively defined with hydraulic, channel-roughness, and geomorphologic variables, and different habitat types showed characteristically different hydraulic dynamics across flows. The analyses also showed that physical habitat could be effectively described by 4 axes (sets of similar variables) at microhabitat scales, although greater covariation occurred at intermediate spatial scales (meso- and macrohabitat level). Habitat assessment for instream-flow analyses can thus be effectively simplified by undertaking visual assessment of several mesohabitat types and/or by measuring only a few physical variables for microhabitat analyses. The differences in hydraulic dynamics among mesohabitat types can simplify determination of changes in the availability of fish habitat across flows. The fish analyses showed that habitat-use guilds of fish species could be effectively defined with aggregated data, i.e., across mesohabitat types or by calculation of fishes' habitat-use means for physical variables. In contrast, unaggregated data (each quadrat considered separately) gave cruder habitat-use segregation of fish species, particularly because fish species were independent of each other at smaller spatial resolutions and larger spatial extents. The 7 guilds included 4 rheophilic (riffle-oriented) and 3 limnophilic groups (pooloriented). Habitat-suitability models developed for these guilds showed that fish selected habitat variables independently, such that simple models can be developed to predict fish abundance in response to differences in habitat availability. In sum, the analyses provided habitat-flow and fish-habitat data that can be interfaced (in future analyses) to predict changes in fish abundance and biodiversity to be expected from permanent changes in flow levels and thus habitat availability. / Ph. D.

The consequences to wildlife of living in contaminated areas with chronic low-dose rates of radiation are still relatively unknown. Laboratory studies using acute radiation have demonstrated that invertebrates are relatively radioresistant compared to other taxa. However, there is little scientific evidence to show how chronic low dose rates affect invertebrates. This is problematic for understanding the consequences to wildlife living in highly contaminated areas and also testing assumptions made for invertebrates by the International Commission on Radiological Protection (ICRP). This thesis was designed to address a number of recommendations have been suggested to improve radioecological studies and help reduce the uncertainty as to effects at low dose rates. These include environmentally relevant laboratory studies (Chapters 2 and 4), improved dosimetry and dose assessments (Chapter 3), investgating confounding factors (Chapter 4) and continuity between laboratory experiments and field work conducted in the Chernobyl Exclusion Zone (CEZ) (Chapter4). Chapter 2 presents an environmentally-relevant experiment testing how bumblebee reproduction and life history is affected by chronic low-dose rates. Unexpectedly, at dose rates equivalent to the CEZ, queen production declined and reproductive timing was altered. The estimation of dose rates to establish a dose-effect relationship for wild animals is difficult and a common criticism of radioecological studies, therefore, Chapter 3 tests whether the common approach to measuring only external ambient dose rates is suitable and whether the inclusion of life-history traits significantly alters the dose rate. The findings from this chapter reiterate the necessity to use dose-assessment tools to test different parameters to estimate dose rate in different scenarios to account for unknown variation. Chapter 4 demonstrates that in areas of elevated dose rates in the CEZ parasite burden was higher and bumblebees did not live as long. These results were reinforced by a laboratory study, which determined bumblebees exposed to increased radiation doses had high parasite burdens and were infected quicker, resulting in reduced longevity. The data in this thesis detected effects below the current dose bands used in international radioprotection and therefore advocate these dose bands be re-evaluated. However, the data do not support studies which have measured adverse effects at dose rates similar to background and suggest that confounding factors such as habitat quality and co-stressors need to be included in field and laboratory studies.

Responses of juvenile steelhead trout to changes in stream habitat resulting from an instream habitat rehabilitation project in Meadow Creek, Oregon were measured from 1991 through 1992 and compared to pre-treatment data from 1987 through 1990. Sixty nine pool-forming, and 59 channel-stabilizing log structures were constructed by the U.S. Forest Service in a 3.7 km reach in 1990. A 20-year flood caused extensive modifications to the instream structures in May 1991. Pool habitat and large wood volume increased in the treatment and the two reference reaches but pool development was greater in the treatment reach compared to the two reference reaches. Summer rearing densities of juvenile steelhead were similar for the treatment and the two reference reaches at the reach scale. Summer rearing densities were lower in the post-treatment period compared to the pre-treatment period for the treatment and two reference reaches. Mean density of juvenile steelhead was higher in complex pools compared to non-complex pools throughout the study area. Mean density of juvenile steelhead was higher in pools associated with large wood from washed-out structures compared to pools associated with intact structures in the treatment reach. Changes in smolt production from the treatment reach following the rehabilitation project could not be determined due to trapping difficulties. Only three percent of the smolts emigrating from the basin overwintered in the treatment reach in 1992. Four life history patterns of juvenile steelhead were identified. Only one of the four life history patterns rears in the Meadow Creek basin until smolting. From these findings I conclude that the instream habitat rehabilitation project did not increase the abundance of juvenile steelhead or smolt production during the first two years after treatment. An extended drought and a 20-year flood may have been the dominant factors controlling abundance of juvenile steelhead over the study period. The Meadow Creek rehabilitation project may have limited success at increasing smolt production because it influences only one of four life history patterns of juvenile steelhead during the entire freshwater rearing phase. / Graduation date: 1997

Thesis (Ph.D.)--Mississippi State University. Department of Wildlife and Fisheries. / Title from title screen. Includes bibliographical references.

The behavioural ecology of duikers (Cephalophus spp.) was studied in mature forest and mixed secondary vegetation around TaI National Park, Cöte d'Ivoire. The most common species in both vegetation types was C. maxwelli, followed by C. dorsalis, C. ogilbyi, C. niger, C. zebra and C. lentinki in mature forest, and C. niger, C. dorsalis and C. sylvicultor in secondary vegetation. Population surveys were carried out by a number of methods. Transect censuses by night were found most efficient in mature forest, whereas in secondary vegetation, only pellet transect censuses and drives into nets were possible. C. maxwelli populations were estimated at about 63 km2 in mature forest and 79 km2 in secondary vegetation. Duikers were primarily frugivorous, but the proportion of leaves taken increased in the season of fruit scarcity. Fruit abundance in different habitats increased with the age of the vegetation. Six C. maxwelli in mature forest and four in secondary vegetation were radio-collared to determine ranging patterns and social behaviour. They were diurnal and lived in groups of one male with one or two females and young. Home ranges, which were about 5 ha in size in mature forest and 3.6 ha in secondary vegetation, were defended by males, and the boundaries were marked by latrine areas by both sexes. In mixed secondary vegetation, all habitats were used except open fields and bamboo thickets. Implications for conservation and management are discussed. The continued preservation of mature forest and the control of poaching are essential for the survival of the three rarer species (C. -jentinki, C. zebra and C. ogilbyi). The control of poaching must precede any programme of sustainable harvesting of the more abundant species, which could be carried out in secondary vegetation. Duiker farming may be possible if low-cost sources of fencing and forage can be identified.

Thesis (Ph.D.)--Mississippi State University. Department of Wildlife and Fisheries. / Title from title screen. Includes bibliographical references.