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Biological Sciences - Theses, Dissertations, and other Required Graduate Degree Essays

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The lethal and sublethal effects of anti-sea lice chemotherapeutants in marine benthic and pelagic invertebrates

Author: 
Date created: 
2021-01-14
Abstract: 

The salmon aquaculture industry has become a major contributor to the Canadian economy, however, many practices including sea lice pest management strategies have resulted in the contamination of the environment near these operations. Compounds used in sea lice control include Salmosan® (active ingredient [AI] azamethiphos), Paramove®50 (AI hydrogen peroxide), ivermectin (IVM) and SLICE® (AI emamectin benzoate [EMB]). Salmosan® and Paramove®50 are water-soluble formulations applied as bath treatments, whereas IVM and SLICE® are in-feed additives that are hydrophobic and partition to sediment with persistent physicochemical properties. This research assessed both the lethal and sub-lethal effects of these compounds on non-target benthic and pelagic invertebrates at environmentally relevant concentrations. A short-term fertilization success bioassay using the sea urchin Strongylocentrotus purpuratus was performed using pest management application-level concentrations of Salmosan® and Paramove®50 in seawater. Paramove®50 significantly inhibited fertilization success with a calculated IC50 value of 7.27 mg/L; Salmosan® only marginally inhibited fertilization at the highest concentration (IC50 > 100 µg/L). Avoidance behaviour and oxygen consumption were assessed in the benthic amphipod, Eohaustorius estuarius, and the polychaete Nereis virens, following sub-chronic exposure to environmentally relevant sediment concentrations (< 5 µg/kg) of EMB, IVM and a combination of both (EMB/IVM). E. estuarius avoided sediment containing IVM and EMB/IVM ratio concentrations containing 25 and 50 µg/kg IVM, while N. virens avoided sediment with 50 and 200 µg/kg IVM and 0.5, 5, 50 and 200 µg/kg EMB/IVM ratio. Impaired burrowing and locomotory behaviour in N. virens was also observed with both treatments. Oxygen consumption was significantly decreased in E. estuarius and increased in N. virens when exposed to EMB, IVM and EMB/IVM at concentrations < 5 µg/kg over a 28-d exposure period. This research provides evidence of impacts to S. purpuratus, E. estuarius and N. virens from anti-sea lice chemotherapeutant exposure at environmentally relevant concentrations and will supplement regulatory decisions and management policies associated with chemicals used in aquaculture in Canada.

Document type: 
Graduating extended essay / Research project
File(s): 
Supervisor(s): 
Christopher Kennedy
Department: 
Science: Biological Sciences Department
Thesis type: 
(Project) M.E.T.

Polarized light - host location and selection cue in phytophagous insects?

Author: 
Date created: 
2020-12-16
Abstract: 

Insect herbivores exploit plant cues to discern host and non-host plants. Studies of visual plant cues have focused on color despite the inherent polarization sensitivity of insect photoreceptors and the information carried by polarization of foliar reflectance, most notably the degree of linear polarization (DoLP; 0-100%). The DoLP of foliar reflection was hypothesized to be a host plant cue for insects but was never experimentally tested. I investigated the use of these polarization cues by the cabbage white butterfly, Pieris rapae (Pieridae). This butterfly has a complex visual system with several different polarization-sensitive photoreceptors, as characterized with electrophysiology and histology. I applied photo polarimetry revealing large differences in the DoLP of leaf-reflected light among plant species generally and between host and non-host plants of P. rapae specifically. As polarized light cues are directionally dependent, I also tested, and modelled, the effect of approach trajectory on the polarization of plant-reflected light and the resulting attractiveness to P. rapae, showing that certain approach trajectories are optimal for discriminating among plants based on these cues. I then demonstrated that P. rapae exploit the DoLP of foliar reflections to discriminate among plants. In experiments with paired digital plant images that allowed for independent control of polarization, color and intensity, P. rapae females preferred images of the host plant cabbage with a low DoLP (31%) to images of the non-host plant potato with a high DoLP (50%). These results indicated that the DoLP had a greater effect on foraging decisions than the differential color, intensity or shape of the two plant images. To investigate potential neurological mechanisms, I designed behavioral bioassays presenting choices between images that differed in color, intensity and/or DoLP. The combined results of these bioassays suggest that several photoreceptor classes are involved and that P. rapae females process and interpret polarization reflections in a way different from that described for other polarization-sensitive taxa. My work has focused on P. rapae and its host plants but there is every reason to believe that the DoLP of foliar reflection is an essential plant cue that may commonly be exploited by foraging insect herbivores

Document type: 
Thesis
File(s): 
Supervisor(s): 
Gerhard Gries
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

Regimes of river temperature and flow in an interior watershed, and their implications for Chinook salmon

Author: 
Date created: 
2020-12-07
Abstract: 

Climate change and human activities are altering river flows and temperatures, with potentially large consequences for aquatic life. I investigated how changing river flows affect salmon productivity, and how climate sensitivity varies across a watershed. First, I tested the effects of shifting river conditions on Chinook salmon productivity in a river where average August river discharge decreased by 26% in the last century. Summer low flows had the greatest negative impact on productivity: cohorts that experienced 50% below average flow in the August of spawning and rearing had 40% lower productivity. Second, I examined whether watershed characteristics could predict which streams were warmest and most sensitive to regional climate. Streams with more riparian forest cover were cooler overall and less sensitive to warmer air temperatures. Overall, this research shows that restoring river flows and watershed-scale forest management are essential parts of salmon conservation.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Jonathan Moore
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Temporal patterns and behavioural states of mountain goat (Oreamnos americanus) movements to hotspots in the Rocky Mountains

Author: 
Date created: 
2020-12-01
Abstract: 

Concentrated resources, or hotspots, can influence movement behaviour of many species. I studied the movement ecology of two groups of mountain goats (Oreamnos americanus) and their relationship with hotspots in the Canadian Rocky Mountains. First, I investigated fidelity to two roadside mineral licks. Movement patterns to mineral licks were documented over several temporal scales and I found that mountain goats have strong trans-generational, seasonal and daily movements to these mineral licks. Second, I investigated movements to foraging, travelling, and bedding areas in summer ranges, using hidden Markov models (HMMs) and predicted behavioural states. These behavioural states were ground validated and the results showed that HMMs can be used as a proxy for habitat hotspots. Understanding how animals adjust their movement behaviour to hotspots can provide valuable information for the management of these critical habitat features and the wider conservation of mountain goats.

Document type: 
Thesis
File(s): 
Supervisor(s): 
David Hik
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

The continuing persistence and biomagnification of DDT and metabolites in American robin (Turdus migratorius) fruit orchard food chains

Author: 
Date created: 
2020-12-14
Abstract: 

DDT is an organochlorine insecticide that was widely used in fruit orchards in the South Okanagan Valley from the late 1940s and in the 1990s, this was documented to have caused extensive contamination of American robin (Turdus migratorius) food chains. Due to the environmental persistence of DDT and its metabolite, p,p’-DDE, the objective of this study was to re-sample previous orchards, as well as several new agricultural areas with the prediction that DDT and metabolite concentrations would significantly decline twenty-six years after a similar sample collection was conducted in 1993-1995. This was done by: 1) collecting soil, earthworms and American robin eggs from orchard and non-orchard areas in the South Okanagan Valley, 2) comparing previous and current contaminant burdens for DDE, DDT and DDD metabolites, and 3) calculating biomagnification factors for earthworms and robins on a lipid normalized basis. All robin eggs contained DDE, DDT and DDD, with the highest concentration being p,p’-DDE at 107 ug/g (wet weight), confirming that contamination is still present at similar and high levels relative to the 1990s. DDE and DDT levels in robins were significantly higher than Aporrectodea and Lumbricidae earthworms, and earthworm-robin regressions for DDE showed a significant positive relationship. Biomagnification factors were generally > 1 and were higher for DDE than DDT and DDD. Concentrations of p,p’-DDE in American robins in this study were comparable to and/or exceeded published levels in other migratory birds nesting in fruit orchards, including the eastern bluebird (Sialia sialis), where reproductive and immunostimulation effects were observed. The relatively high concentrations of DDE in the South Okanagan Valley may pose a health risk to local predators and birds of prey, such as Accipiter hawks and falcons, who often feed at higher trophic levels where DDE and other contaminants are biomagnified.

Document type: 
Graduating extended essay / Research project
File(s): 
Supervisor(s): 
John Elliott
Department: 
Science: Biological Sciences Department
Thesis type: 
(Project) M.E.T.

Attraction of brown marmorated stink bugs, Halyomorpha halys, to blooming sunflower semiochemicals

Author: 
Date created: 
2020-12-14
Abstract: 

I tested whether the brown marmorated stink bug (BMSB), Halyomorpha halys, discriminates among phenological stages of sunflower, Helianthus annuus. When BMSB females in a still-air laboratory experiment were offered a choice of potted sunflowers at distinct phenological stages (vegetative, pre-bloom, bloom, seeding), most females settled onto blooming plants. In moving air olfactometer experiments, testing each plant stage versus one another, for the attraction of BMSB females, blooming sunflowers overall were most attractive. Analyzing the headspace odorants of each plant stage revealed a marked increase of odorant abundance as plants transitioned from pre-bloom to bloom. Thirteen blooming-stage odorants elicited responses from female BMSB antennae. A synthetic blend of antennally-active odorants attracted BMSB females in laboratory olfactometer experiments, and in field settings enhanced the attractiveness of BMSB pheromone as a trap lure, particularly in spring. Sunflower semiochemicals coupled with synthetic BMSB pheromone could be developed to improve efforts to monitor and control BMSB populations.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Gerhard Gries
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.P.M.

Post-harvest recovery of a co-managed First Nations’ gooseneck barnacle fishery

Author: 
Date created: 
2020-12-16
Abstract: 

Small-scale fisheries are culturally significant and provide coastal communities with economic opportunities. On the west coast of Vancouver Island, British Columbia, five First Nations co-manage a small-scale commercial fishery for gooseneck barnacles (Pollicipes polymerus). To inform the sustainable expansion of this fishery, I conducted an experimental harvest to estimate post-harvest recovery of gooseneck barnacles, the biotic matrix (i.e., acorn and thatched barnacles and mussels), and bycatch of mussels. After 14 months, mean matrix recovery was 74% of its initial cover, while gooseneck barnacle biomass recovery was only 12%. Both were highly variable and none of the variables tested was able to predict recovery of the matrix or of gooseneck barnacles. These results suggest that other factors, such as space, larval supply, and a longer time period, might contribute to both matrix and gooseneck barnacle recovery. Bycatch of mussels, in terms of biomass, increased by 2% with each 1% increase in biomass of gooseneck barnacle harvested, and this effect increased with matrix depth. These findings can inform management, suggesting that if harvest effort increases, the 6-month rotational closure should be re-visited, and that bycatch can be addressed through simple management measures.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Isabelle Côté
John Reynolds
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Metabolic connections to life history in fishes

Author: 
Date created: 
2020-12-09
Abstract: 

Metabolic rate is often assumed to set the pace of life histories because organisms depend upon the energy acquired through metabolism for survival, growth, and reproduction. However, key links between metabolic rate, morphology, and ecology remain unexamined. First, I examined the energetics behind brain size in the blacktip shark (Carcharhinus limbatus) using gill surface area as an integrated correlate of metabolic rate. Both brain mass and gill surface area increased with body mass throughout ontogeny and individuals with larger brains for their body mass also had larger gill surface areas. Second, I asked whether life history traits explained variation in resting metabolic rate across fishes and found that only growth performance, which encompasses the trade-off between growth and maximum size, explained variation. Collectively, this work illustrates the importance of energetic trade-offs and emphasizes the need for empirical tests of assumptions and an integrated view of physiology and ecology.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Nicholas Dulvy
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Hotspots in the marine realm: The where and why of shark and ray biodiversity

Author: 
Date created: 
2020-12-04
Abstract: 

Understanding the spatial distribution patterns of species is critical for determining the mechanisms behind marine biodiversity and appropriating conservation efforts. I used the distribution maps of all known marine species in the class Chondrichthyes to explore the degree of spatial congruency across three measures of species richness hotspot, as well as their threatened counterparts. Overall, spatial congruency was low, suggesting that conservation attention should not focus solely on areas of high species richness. I then investigated the abiotic and biotic drivers of global species richness. Sea surface temperature, productivity, and oceanic upwellings were some of the strongest abiotic predictors for richness. Areas of high richness also comprised many small ranging, younger species, indicative of species diversification occurring in the tropics. This work predominantly highlights the importance of considering which measure of richness we use when approaching conservation and advances our understanding of the biogeography of sharks and rays in the marine realm.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Nick Dulvy
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Climate change and glacier retreat in salmon watersheds

Author: 
Date created: 
2020-12-09
Abstract: 

Global air temperatures are projected to rise over the next century following the continued increase and amplification of greenhouse gas emissions, mainly due to human activity. This rise in air temperature will pose significant changes to the landscape, most notably glacier retreat. Salmon watersheds beheaded by glaciers will undergo drastic changes as ice melts from the landscape changing downstream river flow, water temperature, and channel morphology, and shifting nutrients and availability of prey resources. Broadly, my thesis provides insight on how the effects of climate change, particularly from glacier retreat, may present challenges and benefits to Pacific salmon. In chapter 2, I explore the ways in which glacier retreat impacts salmon habitat by reviewing and constructing a conceptual model that defines glacier retreat across four distinct phases, from a landscape blanketed by ice to complete deglaciation. I describe each of these pathways of impact and how they will affect Pacific salmon across the four phases. In chapter 3, I quantify how much new Pacific salmon habitat will be created by glacier retreat over the next century. I found that glacier retreat will create hot spots of future habitat gains within glacierized regions of western North America, while other areas will experience no habitat gain. In my fourth chapter, I assessed how water temperatures along an important Pacific salmon migratory river are associated with landscape features of tributary systems. I placed temperature loggers at all major tributary rivers and determined how they play a role in cooling a major salmon migratory corridor. Glacier and snowpack fed tributaries from larger watersheds cooled a major salmon migratory river more than other tributaries. Collectively, this thesis provides insight into how climate change and glacier retreat impact river systems and their salmon. This work illuminates the need for forward-looking conservation and management to aid in the protection and preservation of important and iconic species, such as Pacific salmon.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Jonathan W. Moore
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.