Graduate Research

Permanent URI for this community

https://unbscholar.lib.unb.ca/handle/1882/12776

Browse

Now showing 1 - 20 of 209

A comparative study of invertebrate food web structure in two adjacent tributaries of the Slave River with divergent chemistry
(University of New Brunswick, 2020) Hussey, Beverly; Baird, Donald; Soto, David
This study examines benthic invertebrate assemblages of two contrasting river systems: the Salt River and Dog River, adjacent tributaries of the Slave River, located near the town of Fort Smith, Northwest Territories. The study sites, located in different ecoregions, express contrasting geophysical and geochemical characteristics: the Salt River draining karst geology and the Dog River draining Canadian Shield geology. Prior to this study, these two rivers were relatively unstudied by scientists, despite their significance for water and cultural resources to indigenous people of the area. At the time of this study, interest in exploring the potential use of these sites as part of the CanadaAlberta Oil Sands Monitoring program was being explored. The purpose of this study was therefore to gain baseline knowledge about these systems for future biomonitoring purposes. The objectives of this thesis were to examine and compare community composition, taxon richness and prevalence, and trophic structure of the benthic invertebrate communities. Results showed significant differences in taxon richness, prevalence, and trophic structure of the benthic assemblages between the two rivers. The results suggests [sic] that the geophysical and geochemical differences between the two rivers led to differences between the benthic invertebrate communities.
A glider-mounted shadowgraph camera as a tool for quantifying meso- and gelatinous zooplankton distribution
(University of New Brunswick, 2024-04) Hynes, Natasha J.; Davies, Kimberley
Monitoring zooplankton populations, especially those of energy-rich copepods, is of interest due to their roles as prey for many commercially important and endangered marine species. Autonomous sampling could help improve fine-scale temporal and spatial monitoring, complimenting conventional methods. Here, I evaluate the performance of a prototype, glider-mounted shadowgraph camera for estimating zooplankton identifications and concentrations. The evaluation was completed via a gear-comparison with standard samplers (a MultiNet Midi and UVP6-HF). Copepods were the most abundant taxon in the zooplankton community and the shadowgraph yielded mostly definite identifications, while the UVP6 had more uncertainties. The shadowgraph and UVP underestimated concentrations compared to the MultiNet, yet correlations were significant with both imaging sensors. The shadowgraph, with a Spearman correlation of 0.73 with the MultiNet, excelled at detecting vertical copepod layers and further studies should explore the shadowgraph’s ability to detect diel-vertical migration and develop machine learning tools to aid finer taxonomic identification.
A late-Holocene reconstruction of forest moth outbreaks in central New Brunswick, Canada
(University of New Brunswick, 2020) Milbury, Kristen Jane; Cwynar, Les
Fossil lepidopteran scales found in lake sediments are a new proxy for reconstructing population outbreaks of important forest moth pests such as spruce budworm (Choristoneura fumiferana Clemens), hemlock looper (Lambdina fiscellaria Guenée), and forest tent caterpillar (Malacosoma disstria Hübner). We introduce a new method to distinguish these pests and two others, eastern blackheaded budworm (Acleris variana Fernie) and jack pine budworm (Choristoneura pinus Freeman), by traits on their wingscale ultrastructure as seen using scanning electron microscopy. We made qualitative and quantitative comparisons of morphological traits at the ultrastructural level and found that hemlock looper and eastern blackheaded budworm scales could be categorically separated from each other and from the three other species. The remaining three species were not as easily distinguished, especially when trying to identify unknown fossil scales. Using this new proxy, we produced a high-resolution record of fossil lepidopteran scales using a 173-cm sediment core collected from Killarney Lake, in central New Brunswick, Canada. Our results show that fossil scales were abundant and well preserved over a 1620-year period. A total of 29 scale peaks were detected for an average periodicity of 55.8 years.
A molecular systematic and taxonomic assessment of the Rhodymeniales
(University of New Brunswick, 2016) Filloramo, Gina; Saunders, Gary
The assessment of biological diversity and understanding the evolutionary history of organisms is integral to understanding life on earth. The Rhodymeniales is a well-defined red algal order for which interfamilial relationships are incompletely understood and species identification is complicated by the inability of traditional morphology-based approaches to reconcile convergent features and phenotypic plasticity. In this thesis, I used an integrative taxonomic approach combining molecular and morphological techniques to address rhodymenialean phylogenetic relationships and species diversity. I implemented multi-gene phylogenetics and site-stripping analyses to uncover reasonable support for interfamilial relationships within the Rhodymeniales for the first time. As part of that study, I established the phylogenetic assignment of some taxa (Binghamiopsis, Chamaebotrys, Minium) previously missing from molecular analyses, restored monophyly to notoriously polyphyletic genera by establishing Perbella gen. nov. and Fushitsunagia gen. nov., and described three novel Australian species of Drouetia (D. aggregata sp. nov., D. scutellata sp. nov., D. viridescens sp. nov.) after clarifying tetrasporangial development for that genus. Identification of recently collected material from Australia as the generitype of Leptofauchea facilitated a re-examination of that genus and its constituent species. Multigene phylogenetics provided support for Leptofauchea as a monophyletic genus for the first time. Additionally, inconsistencies with published accounts of some Leptofauchea species were clarified and two novel species (L.cocosana sp. nov., L. munseumica sp. nov.) assigned to that genus were recognized. A molecular-assisted alpha taxonomic approach employing the 5’ end of the mitochondrial cytochrome c oxidase subunit I (COI-5P) DNA barcode was implemented to reassess species diversity and redefine inaccurate or inadequate species concepts for rhodymenialean taxa in British Columbia. I resolved 16 species in 10 genera where 13 species in 11 genera were previously reported, uncovering underestimated diversity for the genera Botryocladia, Faucheocolax, Fryeella, Gloiocladia and Rhodymenia. The previous necessitated a taxonomic transfer (Fryeella callophyllidoides comb. nov. for Rhodymenia callophyllidoides), the resurrection of a previously synonymized species epithet (R. rhizoides) and the establishment of novel taxa (B. hawkesii sp. nov., R. bamfieldensis sp. nov.). That study also included reassessment of anatomical development for the monospecific genus Minium. Lastly, a comprehensive floristic survey of the genus Rhodymenia from Australia was performed using molecular-assisted alpha taxonomy with COI-5P and ITS sequence data as the genetic markers. Whereas five species were previously reported, I resolved 12 genetic groups. Four of those groups were attributed to previously recognized species, whereas some collections were attributed to a New Zealand species, R. novazelandica, expanding its biogeographical range. The remaining seven genetic groups were inconsistent with existing species of Rhodymenia and established as novel taxa (R. compressa sp. nov., R. contortuplicata sp. nov., R. gladiata sp. nov., R. insularis sp. nov., R. lociperonica sp. nov., R. norfolkensis sp. nov., R. womersleyi sp. nov.).
A suppressor mutation approach to determining the sequence requirements of an unusual two-subunit sigma factor and its cognate promoter element
(University of New Brunswick, 2017) Kesthely, Christopher, Andrew; MacLellan, Shawn
Transcription is a highly-regulated process. In bacteria, σ factors are transcription factors that regulate RNA polymerase binding to promoters, and the conversion of double stranded DNA to the single-stranded state required for the initiation of RNA synthesis. The Bacillus subtilis genome encodes an atypical, twosubunit σ factor called SigO-RsoA. To better understand the genes regulated by this σ factor, I conducted the largest phylogenetic analysis of the SigO-RsoA regulon to date and compiled and analyzed the sequences of 216 orthologous target promoters. A comprehensive mutational analysis of a conserved thymine trinucleotide and a -10 promoter element cognate to SigO-RsoA delineated key nucleotides required for the activity of this σ factor. Selected inactive promoter mutants were used in a suppressor mutation approach to identify whether it is SigO or RsoA that is responsible for interaction with the key -10 promoter element.
Activity of a Drosophila teissieri I-element retrotransposon in Drosophila melanogaster
(University of New Brunswick, 2020) Miller, Lauren Marie; Clark, Denise
Transposable elements play an important role in evolution, affecting genome structure and gene regulation. A retrotransposon reverse transcribes its own RNA to create a cDNA copy that is inserted in the genome, and its machinery can reverse transcribe other RNAs to produce retroduplications. The human L1 retrotransposon gene product ORF1 protein (ORF1p) has RNA-binding activity, while the ORF2 protein (ORF2p) is a reverse transcriptase and has endonuclease activity. The transposition of the I-element, an L1-related retrotransposon in Drosophila species, has been studied in vivo. In this study, a cloned D. teissieri I-element was designed to explore binding preferences of ORF1p to cellular transcripts in the germline to contribute to understanding the process of retroduplication. To determine the types of RNA that are associating with ORF1p, three transgenic D. melanogaster strains were constructed. One transgenic strain expresses an epitope-tagged HA-ORF1p. Expression of HA-ORF1p in ovaries, followed by immunoprecipitation to isolate ribonucleoprotein particles (RNPs) bound to HA-ORF1p, would allow for the ORF1p-bound RNAs to be isolated. The other two transgenic strains were used to assess the full-length I-element clone for its ability to transpose, and to determine if the HA epitope tag in ORF1p affects this transposition. I determined that there is RNA expression of the I-element transgenes while using a GAL4 driver; however, assays used to detect new DNA copies of the I-element were negative, as were assays to detect female sterility induced by I-element activity, suggesting that this I-element has little to no transposition activity.
Acute and chronic effects of oil sands process water components on the mayfly Hexagenia and field-collected aquatic macroinvertebrate communities
(University of New Brunswick, 2019) Howland, Julia; Alexander-Trusiak, Alexa; Culp, Joseph
Tailings ponds in northeastern Alberta, Canada contain over one trillion litres of oil sands process water (OSPW) that cannot currently be released due to toxicity of some components. Limited space and the need for reclamation of oil sands operation sites necessitates release of OSPW in the near future. Knowledge of the composition and toxicity of OSPW is often lacking yet is crucial for both risk assessment and management planning. This thesis examines the acute and chronic toxicity of environmentally relevant mixtures of two process water components, naphthenic acid and sodium naphthenate, with and without the added stress of polycyclic aromatic hydrocarbon spiked sediment. We assess the effects of these simplified oil sands process water (OSPW) mixtures under planned and un-planned tailings release scenarios using traditional and novel bioindicators for aquatic invertebrate taxa. The results of this study demonstrate the significant negative effects of OSPW contaminants on aquatic communities.
Age validation, size-at-age, size-at-maturity, and age-at-maturity in snow crab (Chionoecetes opilio) from different thermal regimes in Newfoundland
(University of New Brunswick, 2020) Catlin, Nicole; Rochette, Rémy; Kilada, Raouf
Calcein dye was used to determine the deposition rate of growth bands on snow crab gastric mill ossicles, although this was unsuccessful due to dye leaching. Annual deposition of growth bands was, however, corroborated based on age estimates from size-frequency histograms. There is limited understanding of the effects of temperature on snow crab growth and sexual maturation. Band counts revealed no significant difference in size-at-age, size-at-maturity, and age-at-maturity between crabs inhabiting “colder” and “warmer” waters around Newfoundland, but a significant difference in size-at-age and size-at-maturity between males (larger) and females (smaller) was found. Some of my findings were consistent and others inconsistent, with the literature, which may have been partly due to a warming trend preceding this study and/or crab movements. Future studies should attempt to relate snow crab growth and maturation to the temperature they experience throughout their lifetime, which should assist fisheries management in a rapidly changing climate.
Among-lake variability in Methylmercury and amino acids in aquatic invertebrates from Kejimkujik National Park
(University of New Brunswick, 2017) Thera, Jennifer, C; Kidd, Karen
Methylmercury (MeHg) is a neurotoxicant that is known to biomagnify in food webs and can result in fish consumption advisories. In aquatic invertebrates, MeHg concentrations are known to be highly variable (up to 30-fold) within and among freshwater systems and are a key predictor of mercury in fish, as diet is the main route of exposure. As such, there is global interest in understanding why some systems and invertebrate species accumulate more MeHg than others. The factors driving MeHg variability in aquatic invertebrates are not fully understood, but appear to correlate in part with diet and the physical and chemical parameters of the system. Since MeHg is primarily bound to the amino acid cysteine in proteins, my hypotheses were that cysteine content will be species-specific and that it will explain the within and among taxa variability in MeHg. In 2013 and 2014, food web taxa (benthic invertebrates, zooplankton, and fish) were collected from six lakes within Kejimkujik National Park, Nova Scotia, Canada that are known to vary in physical and chemical characteristics and biotic MeHg. Accurate detection and quantification of amino acids (especially thiols) are needed before they can be applied to the understanding of MeHg variability. I developed and validated a UPLC method to analyze amino acids in aquatic invertebrates, biofilm, and fish muscle. Overall, performance characteristics were reproducible, accurate, and comparable to other methods and tissues. The amino acid compositions of aquatic invertebrates, an understudied group, were significantly different based largely on their percentages of cysteine, histidine, proline, and aspartic acid + asparagine. Cysteine content differed among invertebrate taxa, with the lowest concentrations in Limnephilidae caddisflies (4.67 ± 0.58 nmol mg-1 tissue) and the highest concentrations in zooplankton (7.82 ± 2.88 nmol mg-1 tissue), but not among lakes (pH range 5.5-6.2). Primary consumers feeding on a benthic carbon source (Limnephilidae and Heptageniidae) had less cysteine and less MeHg than the pelagic primary consumers (bulk zooplankton). MeHg was significantly and positively related to cysteine content in five of the seven taxa. Despite this, more of the within-taxa variability was explained by δ15N, although this does not hold true when isotope data were adjusted for among-system differences in basal δ15N. This research generated new knowledge on 1) the importance of phylogenetics, diet, and lake characteristics in determining the amino acid composition of aquatic invertebrates and 2) on cysteine as a predictor of MeHg concentrations within aquatic invertebrates.
An environmental DNA metabarcoding approach to monitoring red algal biodiversity
(University of New Brunswick, 2023-10) Crichton, Josephine; Saunders, Gary W.; Reyes-Prieto, Adrian
Biodiversity monitoring is an important tool in ecosystem conservation as it can provide reliable detection of invasive species, indicate resilience after disaster, and serves as evidence for successful management of resources or ecosystems. Despite biodiversity loss being one of our most critical conservation challenges, biodiversity monitoring in marine ecosystems is typically conducted using molecular-assisted alpha taxonomic (MAAT) surveys, which have several limitations. This study compares red algal species richness and compositional diversity detected using environmental DNA (eDNA) metabarcoding to that detected using a typical MAAT survey. My aim was to determine if eDNA analyses provide a cost-effective and comprehensive alternative to traditional survey methods, and to improve upon the currently available reference libraries for red algae. The results of this support a growing bank of literature suggesting that a combination of MAAT and eDNA methods remains the best approach for maximizing species detection.
An epitope-tagged reporter to detect MMP activation in vivo: Mmp2 activation patterns reveal Mmp14-independent regulation in zebrafish embryos
(University of New Brunswick, 2017) Jeffrey, Emma, Jayne; Crawford, Bryan
Matrix metalloproteinases (MMPs) are secreted proteases that remodel the extracellular matrix (ECM) during development, disease, and other physiological processes. The ECM provides support for tissues and regulates the activity of surrounding cells. To prevent inappropriate activity, MMPs are synthesized as inactive enzymes. In vitro, MMP-14 activates MMP-2 by proteolytically removing MMP-2’s auto-inhibitory propeptide; however, investigating MMP activation within tissues requires a novel approach. I developed the Epitope-Mediated MMP Activation (EMMA) assay to detect and quantify MMP activation in vivo using immunofluorescence and immunoblotting. EMMAedMmp2 is activated in ECM-rich regions and patterns similar to endogenous protein expression. To investigate the underlying mechanisms of EMMAedMmp2 activation, I analyzed Mmp14α/β sequences and expression patterns. Differences between the two suggest unique roles for each of these paralogues in vivo. Furthermore, using EMMAedMmp2 with pharmacological MMP inhibitors reveals the presence of additional Mmp2 activation mechanisms in developing zebrafish embryos. I also generated a transgenic line of zebrafish expressing EMMAedMmp2 that can be used to investigate MMP activation mechanisms more consistently without the limitations of transient expression. The EMMA Assay is a versatile tool that will improve our understanding of MMP regulation in ECM remodelling and its implications in development and disease.
An investigation into the taxonomy, distribution, seasonality and phenology of Laminariaceae (Phaeophyceae) in Atlantic Canada
(University of New Brunswick, 2014) Longtin, Caroline; Diamond, Antony
The Laminariaceae is one of eight families in the order Laminariales ( the kelps) and most members occur in the northern hemisphere. A recent molecular study in Atlantic Canada confirmed the presence of Laminaria digitata, Saccharina latissima and a third genetic species, which was later attributed to S. groenlandica. This third genetic species was likely overlooked in this region due to its morphological similarity to L. digitata and S. latissima. The main objective of this thesis was to investigate the taxonomy, distribution and seasonality of the Laminariaceae in Atlantic Canada and verify the taxonomic identity of the North American genetic species attributed to S. groenlandica. First, I clarified the taxonomic confusion surrounding the North American genetic species attributed to S. groenlandica. I determined that the North American genetic species currently attributed to S. groenlandica is correctly attributed to L. nigripes; therefore, Saccharina nigripes (J. Agardh) C. Longtin et G.W. Saunders comb. nov. was established and includes North American collections previously attributed to S. groenlandica. Second, I utilized molecular tools to determine the relative abundances of L. digitata, S. nigripes and S. latissima in differing habitats in the Bay of Fundy intertidal zone. I determined that the digitate morphology of S. nigripes can be the major contributor to Laminariaceae community structure at moderate and wave-exposed sites in the Bay of Fundy; however, its abundance fluctuates depending on the year. Third, I attempted to clarify the seasonality and phenology of the Laminariaceae in the Maritime Provinces. Due to the morphological similarity of S. nigripes to L. digitata and S. latissima previous literature on the seasonality and phenology of S. latissima and L. digitata may have inadvertently included S. nigripes. Saccharina nigripes was rare at the study site in the year this study was performed and I was unable to determine its seasonality and phenology. However, I did determine that the seasonality and phenology of L. digitata and S. latissima in this region are consistent with previous reports in Atlantic Canada, and the presence of S. nigripes is unlikely to impact previous literature on the seasonality and phenology of L. digitata and S. latissima.
Anti-mycobacterial natural products from Canadian medicinal plants: identification, confirmation of source and investigation of mode of action
(University of New Brunswick, 2015) Li, Haoxin; Gray, Christopher; Johnson, John
The global epidemic of tuberculosis (TB) persists in large part due to the development of resistance against current therapies. One potential source for novel anti-TB drugs is natural products. Plants and the natural products that they produce have long been recognized for their medicinal value and are extensively used as traditional medicines, and therefore they represent an important source of anti-mycobacterial natural products. The objective of this thesis was to investigate anti-mycobacterial natural products from Canadian medicinal plants. Four plants that have been used to treat TB, Aralia nudicaulis, Alnus incana, Empetrum nigrum and Moneses uniflora, were selected after preliminary anti-mycobacterial screening of 13 Canadian medicinal plants. A total of 21 natural products were isolated through bioassay guided fractionation of the four plants. Aralia nudicaulis was selected for the exploration of its endophytic community and the C17 diynes isolated from A. nudicaulis were investigated to identify their anti-mycobacterial modes of action. As it has been demonstrated that some endophytes can produce natural products originally attributed to their host, we considered it worthwhile investigating whether the C17 diynes isolated from A. nudicaulis were biosynthesized from the plant de novo or whether they were produced by endophytes. As such, 88 endophytic fungi were isolated from rhizomes of A. nudicaulis and were screened for their ability to produce falcarinol and panaxydol. Unfortunately, neither of the C17 diynes could be detected in the endophytes from our screening. Microarray analysis was used to determine the transcript responses of Mycobacterium smegmatis when treated with the C17 diynes, falcarinol and panaxydol. Principal component analysis suggested a different mode of action of the C17 diynes when compared with commonly used anti-mycobacterial drugs. Functional enrichment and pathway enrichment analysis revealed that there were gene ontologies and pathways preferentially affected by the C17 diynes treatments. The theoretical bioactivities of the two C17 diynes were estimated through prediction of activity spectra of substances (PASS). Based upon these analyses, it is hypothesized that the C17 diynes inhibit fatty acid biosynthesis, specifically phospholipid synthesis, in mycobacteria.
Antimycobacterial natural products from Heracleum maximum
(University of New Brunswick, 2012) O'Neill, Taryn Elaine; Gray, Christopher
Tuberculosis is a major global health problem that has limited therapeutic options available. N atural [natural] products have historically p rovided [provided] the majority of anti-infective agents, and represent a promising source of antimycobacterial compounds. The objective of this research was to identify the bioactive constituents of a traditional medicinal plant, Heracleum maximum, through fractionation guided by the microplate resazurin assay (MRA). However, when we tested the methanolic extracts of Heracleum maximum, we found the MRA to be problematic, providing inconsistent results. The conditions of the MRA were optimised to provide a standard screening protocol for use in screening and bioassay-guided fractionation of methanolic plant extracts. The optimised MRA was then used to isolate eight antimycobacterial compounds from the Heracleum maximum extract. Among the isolated compounds the polyacetylene, (3R,8S)-falcarindiol, and the furanocoumarin, 6-isopentenyloxyisobergapten, expressed the greatest inhibitory activities; whereas the remaining furanocoumarins, bergapten, isobergapten, angelicin, sphondin, pimpinellin, and isopimpinellin exhibited only modest activities.
Aspects of the biology of the porbeagle shark (Lamna nasus) in the upper Bay of Fundy determined through a recreational catch-and-release fishery
(University of New Brunswick, 2012) Pratt, Joseph; Turnbull, Steven; Terhune, John
This research represents the first study of Upper Bay of Fundy pelagic sharks. Sampling occurred over three summers (2008-2010) in conjunction with a catch-and-release charter operation (Sharks Unlimited) sailing out of Alma, New Brunswick. Eighty-eight sharks were encountered over the three years, with 58, 16, and 14 shark encounters in 2008, 2009, and 2010 respectively. All but one of the sharks identified to species were porbeagle (Lamna nasus). Total length of the 44 landed sharks ranged from 102-265 cm, and landed sharks were similarly sized (p = 0.940), with the 2008 season showing a significant (p < 0.001) female: male bias. Male sharks were large enough to be considered sexually mature (90% ), while females were not (14.7% ). Tide state was the only environmental variable found to play a significant (p < 0.001) role in shark encounter rate. Distribution patterns showed a preference for a ridge along the New Brunswick shoreline. Only one tagged shark has been recaptured to date, nearly two years after initial tagging
Assessing impacts of green crab (Carcinus maenas) on the abundance of American lobster (Homarus americanus) in nature
(University of New Brunswick, 2012) Wilcox, Mark Alan; Rochette, Remy
The overlapping vertical range of the American lobster (Homarus americanus) and the invasive green crab (Carcinus maenas) along the Western coast of North America offers the potential for predation by green crabs upon early post-settling and juvenile lobsters. I used three approaches to determine if green crabs affect the abundance of lobsters in nature: (1) predator enclosure experiment, (2) molecular analysis of green crab gut contents, and (3) model equation to assess rate of predation based on (i)- the molecular gut content analysis, (ii)- detectable DNA decay function and (iii)- green crab density. The first study suggested no impact of green crab on lobster, the second provided the first evidence of consumption by green crab on free roaming lobster in nature, and the third was ambiguous with respect to the magnitude of this predation. The model equation suggests the potential for large impacts by green crab, however, modifications to the sampling protocol are necessary to obtain a more precise estimate of predation.
Assessing potential influence of larval development time and drift on large-scale spatial connectivity of American lobster (homarus americanus)
(University of New Brunswick, 2014) Quinn, Brady Keith; Rochette, Remy; Chasse, Joel
I used a new larval drift model to investigate potential spatial connectivity of American lobsters at a large scale incorporating most of the species' range. Because temperature-dependent development of lobster larvae might vary across the species' range, I compared a lab study using cold-water larvae with results of previous studies using warm-water larvae, and tested the sensitivity of model predictions to differences in larval development. The relationship between temperature and larval development time differed between warm- and cold-origin larvae, possibly due to adaptation to local thermal regimes. Different larval development scenarios affected the amount of connectivity predicted by the model among areas. The model predicted much potential connectivity among lobster fisheries areas, and predicted retention of larvae in certain areas, and reliance on external larval supply in others. This is important to management, as the amount and direction of connectivity among lobster fisheries can be used to manage them sustainabIy.
Assessing the impacts of disturbance on a floodplain wetland complex: linking macroinvertebrate traits with ecosystem function
(University of New Brunswick, 2019) Rideout, Natalie Kathleen; Baird, Donald
Floodplains are disturbance-driven ecosystems with high spatial and temporal habitat diversity, making them both highly productive and hosts to high biodiversity. The resulting habitat complexity arising from a diversity of disturbance regimes makes floodplains ideal ecosystems to examine interrelationships among biodiversity, biological traits and ecosystem function. Despite the rise in trait-based ecology, taxonomic resolution has imposed limitations, particularly in wetland and floodplain ecosystems where communities are vastly understudied compared to their riverine counterparts. This thesis describes the use of high-throughput genomic sequencing methods to reliably characterize community composition in the Grand Lake Meadows and Portobello Creek wetland complex, New Brunswick, Canada, in unprecedented detail. Overall, this thesis identified connectivity and hydrology as the driving forces in the formation of floodplain wetland habitat patches, influencing historical shoreline change, temperature variation, nutrient and metal retention, macrophyte growth, and carbon storage. These habitat characteristics subsequently filtered for invertebrate traits, shaping the local community and thus ecosystem function. Healthy wetlands with higher primary productivity were associated with greater functional evenness, while habitat patches with increased decomposition rates had low richness, likely comprising highly disturbed habitat. In conclusion, this thesis highlights the importance of studying floodplain and wetland ecosystems as they contain linkages that are drastically different than their in-channel counterparts, and subsequently explores how to define ecosystem health in wetland habitats.
Assessing the suitability of passive bio-collectors for monitoring biodiversity of subtidal cobble-bottom habitat
(University of New Brunswick, 2018) Wittig, Gregory; Rochette, Rémy; Pohle, Gerhard
This study is part of a larger project aiming to develop a tool and program to monitor biodiversity in rocky subtidal habitats using a passive bio-collector filled with cobble. I compared the communities of “settlers” and “crawl-ins” sampled by the bio-collectors to those found on nearby natural cobble substrate, and assessed the effects of cobble size and surface complexity on recruitment into the bio-collectors. The bio-collectors provided a good representation of what was found on the natural substrate, as there was high species overlap (54%) between the two sampling methods and most (80%) species not found in both were exclusive to the bio-collectors. Cobble size was found to have a small but significant effect on recruitment into the bio-collectors, and surface complexity had a significant effect on settlement of an abundant encrusting species (Anomia simplex). Results show that these passive bio-collectors offer a good tool to monitor cobble-bottom communities.
Assessment of water quality and ecosystem techniques to monitor the environmental effects of salmon aquaculture
(University of New Brunswick, 2020) Day, Jonathan; Cooper, Andrew; Chopin, Thierry
Integrated Multi-Trophic Aquaculture (IMTA) diversifies species culture to produce a variety of products and mitigate nutrient impacts associated with finfish culture. This study examined two biological indicators that could be used to assess IMTA performance with respect to changes in nutrient release. Changes in biocolonization of wild fouling species were examined as an indicator of organic nutrients. Bio-collectors were deployed at different distances from finfish sites to determine if differences in the accumulation of fouling species could be used to detect an aquaculture nutrient source. Biomass accumulation was different with respect to distance from farms and it appears that changes in species composition is responsible. Although there were no measurable differences with respect to distance from salmon cages in environmental conditions such as temperature, salinity, pH, turbidity or chlorophyll, further investigation is suggested to better understand the role of site infrastructure. The relationship between algal colour (lightness, chroma, hue) and nitrogen content within Ulva lactuca, Palmaria palmata, and Poryphyra purpurea was also examined as an indicator of inorganic nutrients. Within each species, colour change corresponded to nitrogen concentration in the thallus, but season and location were significant factors. Palmaria palmata and P. purpurea exhibit less predictable relationships between colour and nitrogen and are harder to identify than U. lactuca and would not be reliable indicators at certain times of year or locations. In both studies the use of wild species responses to nutrient availability was influenced by species type and variability in the coastal environment and require further study before application as tools for IMTA performance monitoring and assessment.

Browse

Browsing Graduate Research by Subject "Biology"

Results Per Page

Sort Options