Dissertations / Theses on the topic 'Environmental Sciences|Engineering, Environmental|Agriculture, Fisheries and Aquaculture'

Fish passage success rates through hydraulic infrastructure have been historically low due to flow field conditions that exceed the physical or behavioral capabilities of a given species. Significant efforts to design and modify hydraulic structures for enhanced passage rates have failed to achieve the desired results, with a primary reason being a poor understanding of how fish respond to complex hydraulic conditions. Many contemporary research efforts have targeted the inter-relationship between hydraulics and fish behavior in the laboratory using live fish trials in an attempt to better comprehend these interactions and ultimately provide a basis for the development of biologically-based design criteria. In this study experiments were conducted to assess the behavioral responses along swimming trajectories of western blacknose dace ( Rhinichthys obtusus) in turbulent flow conditions. The objective was to test the hypothesis that the dace would preferentially adjust their swim paths to minimize their exposure to elevated turbulent conditions. Experimental data were collected through digital imaging of dace trajectories for fish that had been released into a shallow flume and allowed to swim through turbulence enhanced flow fields. Additionally, detailed velocity measurements were collected with an acoustic Doppler velocimeter to allow the comparison of dace trajectories to flow field conditions represented by average metrics of turbulent kinetic energy and Reynolds shear stresses. Analysis of the data consisted of the quantification of the proportion of the time that a dace's swim path selected a direction toward a lower magnitude turbulence condition when such an option existed. Fish paths were also graphically compared to turbulence contour plots to qualitatively assess the presence of swim path preferences or patterns. Lastly, video footage of each trial was evaluated to qualitatively assess the presence of novel behaviors that could have implications for the swimming trajectories observed. Results indicate that the dace did not preferentially avoid turbulence at statistically significant levels under the conditions experienced in the flume; however, data do suggest that some behavior relative to turbulence was non-random. Qualitative observations of video footage suggest that non-hydraulic factors, such as the presence of conspecifics and light intensity, also influence the swim path trajectories of the western blacknose dace. Future research will require more targeted turbulent conditions, simultaneous multivariate observations and analyses that factor in non-hydraulically-based behavior and the incorporation of coupled behavioral and hydraulic data at reduced time and length scales for primary variables. It is envisioned that the results of this study can provide guidance for future studies aimed at developing biologically based design criteria for enhanced fish passage at hydraulic infrastructure.

Aquatic environments adjacent to industrialized urban centers typically contain anthropogenic chemicals that may cause disruption of endocrine systems and physiological functions. This study investigated whether sites within San Francisco Bay are associated with endocrine disruption in the indigenous fish, shiner perch. The endocrine system that produces cortisol was tested, since it is critical for physiological regulation of stress response, metabolism, immune function and osmoregulation. The cortisol-producing tissue, the interrenal, was also investigated using proteomics technologies to initiate a process of identifying proteins with altered expression and which may therefore be involved in tissue dysfunction. Disrupted cortisol responses were detected in fish from several locations and they were related to certain kinds of contaminants and to changed expression of at least four interrenal proteins, which include heat shock protein 1, transferrin, calreticulin, and calmodulin. Several interrenal proteins were also newly identified. The approaches used herein have strong prospects as bioanalytical screening methodologies in environmental studies.

Since the 1970s halibut size-at-age has decreased in southcentral Alaska; the mechanisms causing decreased size-at-age are unknown. The objectives of this study were to 1) compare size-at-age of port-sampled fish in Homer to survey samples from Gulf of Alaska; 2) assess stable isotope values (δ ¹³C, δ¹⁵N) of halibut by sex, size, location and date; 3) determine mean stable isotope values for prey; and 4) identify prey associated with smaller and larger size-at-age. We used port-sampled halibut from the Homer sport fishery due to the quantity of available carcasses. Port-sampled fish were generally larger than survey sampled fish from the same region. Halibut had a wide range of stable isotope values that varied with all factors. Prey isotope values were wide and overlapping, allowing for distinctions among teleost, cephalopods, crustaceans and amphipods. Older and younger fish of the same size and sex had different proportions of prey assimilated into their muscle.

Hatchery reared Chinook salmon from California’s Central Valley were fed for 67 days (Apr-Jun, 2008) on fish pellets mixed with either 0, 1, 3, or 5 µg·g⁻¹ methylmercury hydroxide. Weight, fork length, condition factor, and Na⁺,K⁺-ATPase measurements were determined every two weeks and a 96-h seawater challenge was conducted at the conclusion of the experiment.

Results from two-way ANOVA, with treatment and date as independent variables, indicated no significant differences for weight (F_3,32 = 1.38; P = 0.280), length (F_3,32 = 0.986; P = 0.412) and condition factor (_F3,32 = 0.239; P = 0.869). Post-hoc analysis following two-way ANOVA indicated mean ATPase activity in the high (x¯ = 3.08, S.E. = 0.19; P = 0.008) and medium treatments (x¯ = 2.86, S.E. = 0.57; P = 0.017) was significantly increased in early May compared with the control group (x¯ = 1.47, S.E. = 0.34). The results from the 96 h seawater challenge were consistent with those of other studies indicating weight has the greatest influence for survival in the transition from freshwater to seawater. Overall, results from this study indicated methylmercury, a known neurotoxin, altered ATPase activity in fall-run Chinook but did not significantly affect mortality in the transition from freshwater to seawater.

The purpose of this project to was to 1) develop, 2) instruct, 3) evaluate, and 4) revise a 5^th-12^th grade fisheries conservation engineering outreach program entitled Smart Fishing and the Bering Sea (SFBS).

Fishery resources are important to Alaska and Alaskans, but present complex conservation challenges including user conflicts and concerns about unsustainable fishing practices. Increasing Alaska residents' environmental literacy will enhance natural resource management decisions regarding fisheries. The intent of the SFBS program is to introduce students to ecological and economical factors that drive conservation engineering in the Bering Sea pollock fishery. I instructed the SFBS program to 93 students from four different public and private institutions in Anchorage, Alaska. My observations and participants' pre- and post-program concept maps were used to evaluate the effectiveness of the SFBS curriculum. Participants gained content knowledge from this fishery outreach program about the Bering Sea and commercial fishing. Program evaluation analysis and results were used to revise the curriculum and make suggestions to SFBS stakeholders.

The Pacific Coastal ecoregion contains large tracts of economically important forestlands that also serve as critical stream habitat for endangered Salmonids. Excessive fine sediment deposition in streams of this region is a major environmental concern in the region but difficult to measure directly. The use of stream invertebrates to monitor fine sediment conditions in streams requires careful consideration of several important factors that complicate their use as bioindicators including high spatial and temporal variability and covariance with other environmental variables.

To evaluate the use of stream invertebrates as bioindicators of excessive fine sediment, three hypotheses were tested. The first hypothesis was that invertebrates would be related to broad-scale climate variables (Chapter 2). The second hypothesis was that functional aspects of the invertebrate community would serve as useful indicators of excessive fine sediment condition. (Chapter 3). The third hypothesis was that invertebrates in streams with naturally high levels of sediment would be tolerant to fine sediment (<2 mm, Chapter 4). Hypotheses were tested using a temporal data set at two streams in western Oregon, spatial data from 214 sites across the Oregon Coast Range, and in-situ experiment conducted in streams with erosive or resistant geologies.

In the temporal study, both invertebrate density and functional traits were positively related to El Niño strength (R² range = 0.22–0.36, ρ range = 0.008–0.04) and air temperature (R ² range = 0.32–0.49, ρ range = 0.002–0.01). The spatial study identified several environmental and hydrological factors that exhibited strong negative controls on both fine sediment (Mantel r range 0.14–0.25, ρ range = 0.001–0.01) and invertebrate Scrapers (R² range = 0.11–0.14, ρ range = 0.001–0.04). The result of the experimental study provide evidence that invertebrates in streams with erosive geologies exhibit tolerance to sediment addition when compared to invertebrates in resistant geologies (mean loss=15%, ρ <0.01) and that invertebrate grazing traits were most strongly associated with fine sediment dosing frequency (ρ <0.05).

The findings of this research demonstrate the role of geology in shaping invertebrate communities and their functional response to fine sediment addition and identify functional indicators that may be useful in different geologic settings. For environmental managers in the Pacific Coastal ecoregion, these findings are of potential value in assisting with the identification of biologically-relevant changes in stream fine sediment conditions and support efforts to balance economic needs in the region while protecting critical Salmonid habitat.

As replacement and removal of undersized culverts gains momentum as an effective technique for restoring natural stream flows and removing fish passage barriers, it is important to evaluate the benefits of these efforts on the in-stream and adjacent riparian habitat for other species of potential concern. This study compares stream-associated amphibian (SAA) occurrence in streams adjacent to different road crossing structures on unpaved forest roads in the Wilson River watershed located within the Tillamook State Forest, Oregon. Surveys were conducted at road crossing structures for three taxa of SAA; Pacific giant salamander (Dicamptodon tenebrosus), coastal tailed frog (Ascaphus truei), and Columbia torrent salamander (Rhyacotriton kezeri). Statistical models were created to analyze the effect of habitat variables on SAA occupancy, and determine whether those variables changed relative to road crossing structures.

Results showed that coastal tailed frog occupancy was positively associated with dissolved oxygen and crayfish presence, negatively associated with longitude, and had a slight quadratic relationship to channel confinement. Because all sites were highly saturated with oxygen, percent dissolved oxygen was likely a surrogate for one or more other covariates, such as in-stream habitat or substrate size. Detection rates of Pacific giant salamander were too high and detection rates of Columbia torrent salamander were too low to provide reliable models, but they did provide some insight into the factors affecting occupancy in the study area, including information about their interactions with road crossing structures. Occupancy rates of Pacific giant salamanders in the study area appear to be unaffected by road crossings, fish passable or otherwise. Conversely, torrent salamanders seemed to be mostly absent from the study sites altogether, but based on the one stream where they were detected, they are not excluded from occupying fish barrier culvert sites.

Top weighted habitat covariates, including dissolved oxygen, channel confinement, crayfish and fish presence, and flow constriction are all indicators of disturbance that can be linked to road crossings. Although the size and structure of road crossings did not prove to significantly influence SAA occupancy, indicators of stream disturbance that can be related to road crossings were included in the best models for predicting occupancy, demonstrating the importance of reducing disturbance related to road crossings on streams.