Department of Biology (Fredericton)

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Atlantic salmon (Salmo salar) migrations in a large hydropower reservoir and the regulated Saint John River
Atlantic salmon (Salmo salar) migrations in a large hydropower reservoir and the regulated Saint John River
by Amanda Babin, My research focused on evaluating the impacts of the large Mactaquac Generating Station (MGS) reservoir on the migrations of the endangered Outer Bay of Fundy Atlantic salmon (Salmo salar). Salmon respond to flowing waters to determine the direction, timing, and speed of their migrations. A large reach of the Saint John River (SJR) was impounded by the MGS in 1968, transforming the habitat from a freeflowing river to a lacustrine environment with altered and slower flow. I examined all migratory lifestages of Atlantic salmon in the SJR using acoustic telemetry, including pre-smolts, smolts, adults, and post-spawned adults (kelts), as they navigated these environments. Migration rates were compared between the lentic MGS reservoir and the more lotic reaches upriver and downriver of the MGS to assess whether migration is delayed in the reservoir. Nearly all of the tagged salmon experienced migratory delay within the reservoir (medians: smolts 1.3-6.4 d, kelts 3.5-10.5 d, adults 1.5-5.7 d) due to suppressed migration rates (medians: smolts 5.0-13.3 km d[-1 superscript] vs. 15.4-29.3 km d[-1 superscript], kelts 4.4-8.9 km d[-1 superscript] vs. 14.9-36.8 km d[-1 superscript], adults 8.5-20.1 km d[-1 superscript] vs. 19.3-46.9 km d[-1 superscript]). Migration success through the reservoir was higher for downstream migrants (smolts > 81 % and kelts > 82 %) than upstream migrants (adults 47 %). Recommendations informed by these findings with the aim of aiding recovery of this endangered population are given to hydropower and fisheries managers, including: i) changing the spill regime to allow a greater proportion of downstream migrants the option of spillway passage since all but a few smolts and even the earlier kelt migrants were sometimes forced to pass via turbines; ii) constructing a downstream surface-bypass facility which is more economically feasible than increasing spill and is supported by the observed variable passage timing; iii) allowing the free-swim of downstream migrants through bypasses in comparison to a trap-and-haul strategy that was not found to increase survival of smolts; and iv) maintaining trap-and-haul operations for adults migrating upstream of the MGS due to the high proportion of fallbacks and increased energy expenditure from superfluous movements in the reversed direction to the intended migration observed in the reservoir., Electronic Only.
Breakwaters as habitat for sessile intertidal biota in the Southern Gulf of St. Lawrence
Breakwaters as habitat for sessile intertidal biota in the Southern Gulf of St. Lawrence
by Jordan Musetta-Lambert, Increasing human populations are causing rocky breakwaters to become common features along coastlines. However, knowledge is scarce about the role of breakwaters as intertidal habitat. This study is the first to investigate the assemblage ecology of habitat found on rocky breakwaters compared to natural rocky intertidal areas in the North Atlantic coast of North America so that the potential effects of artificial rocky structures can be understood. Percent coverage of macro-algae and macro-invertebrates were quantified on breakwaters near Arisaig, in the Southern Gulf of St. Lawrence (sGSL) to investigate possible temporal confounds in the main study, from June-August 2010. No significant differences were seen over the months for richness and abundance data, and June differed from the July and August for community composition. Then, percent coverage of sessile biota was quantified at exposed and sheltered areas on breakwaters and natural rocky shores along 430 km of the sGSL. Richness and abundance in sheltered areas of breakwaters were both less than in sheltered areas of natural rocky areas. Breakwaters had significantly different community composition compared to natural rocky shores and between wave exposed and sheltered areas. Semibalanus balanoides were more abundant on natural rocky shores than breakwaters and were found in higher abundance at exposed areas than sheltered areas. Ulva intestinalis had higher abundances on breakwaters than natural rocky shorelines and U. intestinalis, Fucus spp. and Ascophyllum spp. had higher abundances in sheltered areas than exposed areas of breakwaters. This study showed that biotic communities on breakwaters are substantially different than the surrounding natural rocky shores throughout the sGSL., Electronic Only., M.Sc. University of New Brunswick, Department of Biology, 2013.
Characterization of Parelaphostrongylus tenuis excretory glands and identification of alpha-Gal-modified excreted/secreted proteins
Characterization of Parelaphostrongylus tenuis excretory glands and identification of alpha-Gal-modified excreted/secreted proteins
by Jennifer Fitzpatrick, Adult Parelaphostrongylus tenuis induce a concomitant immunity that protects their deer host against subsequent infections. Although this phenomenon is common among longlived parasitic helminths, molecular mechanisms that mediate concomitant immunity remain unknown. Alpha-Gal is a disaccharide that is stage-restricted, synthesized exclusively by adult stage P. tenuis, suggesting a potential role in mediating concomitant immunity. Current studies identified excretory glands as the principle source of alpha-Gal-modified glycoproteins. Secretory granules are the dominant component of these specialized cells, confirming a primary role for excretory glands in protein secretion and, by extension, parasitism. The alpha-Gal epitope is also synthesized within the deer host and so parasite-derived alpha-Gal is poised to promote immune modulation. A model is proposed for alpha-Gal-mediated modulation of host immune responses to promote concomitant immunity. Two-dimensional immunoblots and mass spectrometry identified galectin and/or Ancylostoma-secreted protein homologues as likely candidates for modification by alpha-Gal.
Colonization dynamics of experimentally disturbed areas of mudflat in the upper Bay of Fundy, Canada
Colonization dynamics of experimentally disturbed areas of mudflat in the upper Bay of Fundy, Canada
by Gregory S. Norris, Spatiotemporal variation in community composition results from regional and local factors. My objective was to assess the importance of certain local interactions (ecological successional mechanisms) and regional aspects (regional taxa pool) on infaunal diversity patterns in the upper Bay of Fundy's mudflats. I created local areas with severe disturbance and observed the infaunal community over ~2 months. I did this 4 times over 2 years and found that start time did not change the outcome: infaunal community composition in experimentally disturbed plots became similar to controls through time. I found significant correlations between infauna and water column invertebrates, and taxa that survived disturbance did not inhibit the arrival of subsequent taxa. My study demonstrated that ecological successional mechanisms were not influential on infaunal community composition in the upper Bay of Fundy, and that regional species diversity and invertebrate dispersal should be considered when evaluating infaunal diversity patterns in the future., Electronic Only.
Comparison of small mammal and herpetofauna community composition in naturally regenerated clear-cuts, pre-commercially thinned, and soft-wood plantation forests, at two developmental stages
Comparison of small mammal and herpetofauna community composition in naturally regenerated clear-cuts, pre-commercially thinned, and soft-wood plantation forests, at two developmental stages
by Emilie Day, A viable softwood forestry industry relies on intensive forest management practices to optimize yield, and reduce rotation time. In New Brunswick, Canada, the primary management strategies are plantations followed by herbicide spraying, or naturally regenerated stands that are selectively pre-commercially thinned. Forest managers have both economic and conservation targets so it is critical to understand (1) how managed stands provide habitat value to native biodiversity relative to natural Acadian mixed-wood forest and (2) how the succession since the management intervention (i.e. time since clear-cutting, planting, thinning, etc.) affects habitat quality. This thesis addresses these questions by estimating and comparing small mammal and herpetofauna abundance and taxonomic richness in plantations, thinned, and naturally regenerated stands at two different developmental stages following clear-cutting. Stand characteristics within these treatment and stage categories were surveyed, in order to develop hypotheses about the mechanisms underlying relationships between stand treatment and development stage, and taxonomic richness or individual species abundances. Abundance and taxonomic richness of small mammals, and forest dependent amphibians (wood frog and red-backed salamander), were negatively affected by intensive forest management practices, with plantations having a greater effect than pre-commercially thinned stands. Small mammal richness and abundance, and specifically abundances of Sorex, red-backed voles (Myodes gapperi), wood frogs (Lithobates sylvatica), and red-backed salamanders (Plethodon cinerus), were greater in naturally regenerated mixed-wood stands than in pre-commercially thinned and planted stands. Associations with stand characteristics were species specific, but deciduous components (i.e. canopy cover, leaf litter, percentage of hardwood) were important for species negatively affected by management practices. This is particularly true of canopy cover, which was greatest in naturally regenerated mixed-woods, and lowest in plantations. The relationship between thinning and native small mammal and herpetofauna species was relatively subtle and should be further studied to address the question of whether there are critical thresholds. Contrary to previous studies, no overall effect of forest management was found for herpetofauna taxonomic richness, woodland jumping mouse (Napeozapus insignis), short-tailed shrew (Blarina brevicauda), or deer mouse (Peromyscus maniculatus) abundances, however, this study may not have had the power to detect small effects. Both small mammals and herpetofauna were more abundant in the earlier development stage than the later, but taxonomic richness was similar between stand stages. This highlights the importance of measuring abundance and taxonomic richness, as particular species may be present but reduced in abundance in managed stands. Wood frog and red-backed salamander, two species that are more dependent on a terrestrial life stage than other amphibian species in the region, were positively associated with stand stage. This is likely due to increased canopy closure and resulting higher moisture microclimate levels at later developmental stages. Effective management for small mammal and herpetofauna habitat will require the conservation of mixed-wood stands with a high amount of closed canopy cover.
Description of high-resolution flow velocity and dilution within aquaculture farms in Passamaquoddy Bay, Bay of Fundy, Canada.
Description of high-resolution flow velocity and dilution within aquaculture farms in Passamaquoddy Bay, Bay of Fundy, Canada.
by Taryn Minch, Water flow through aquaculture farms drives the transport of substances (nutrients, therapeutants and pathogens); however, little is known about the spatial and temporal complexity of water flow at the farm scale. In this study, we quantified flow velocity and dilution at high-resolution (one meter) within Atlantic salmon farms in Passamaquoddy Bay, in the Bay of Fundy. Results suggest that Acoustic Doppler Current Profilers are an effective tool to obtain higher-resolution spatial estimates of water flow to describe particle movement within aquaculture farms. We observed considerable variation in water speed and direction between farms and tidal stages. Variation in the dilution of tracer (milk) was also detected between farms and sampling days and overall milk was diluted to 19 percent of initial concentration in 2.5 minutes (15 meters). Results suggest that farms need to be viewed as unique environments, and illustrate the need to consider the variability of current speed, direction and dilution effect within aquaculture farms.
Diversity patterns of benthic diatoms and their use as potential bioindicators in western boreal wetlands
Diversity patterns of benthic diatoms and their use as potential bioindicators in western boreal wetlands
by Stephanie J. Conner, Widespread habitat degradation associated with resource development in Canada’s boreal zone is a major and ongoing threat to biodiversity and ecological integrity. Despite the extensive and intensive development occurring in these regions, little information exists on biological diversity and the potential impacts associated with expansion in Canada’s north. Wetlands are a prevalent landscape feature in the boreal zone and provide many ecosystem services currently at risk of being reduced or lost. In this thesis, diversity patterns of diatom communities in boreal wetlands in Canada’s largest freshwater delta - the Peace-Athabasca Delta in northern Alberta – are examined and assessed for their potential use as indicators in a large-scale biomonitoring program for the federal government. This work has shown that the traditional bioindicator, benthic macroinvertebrates, are not always sufficient indicators of all potential impacts on their own, and that diatoms may be responding to different environmental drivers than the benthic macroinvertebrates in these wetlands. In conclusion, this thesis establishes the need for expansion of standard biomonitoring protocols to include the primary producer community in order to effectively predict future anthropogenic-induced habitat change.
Do impacts from forest harvesting spatially accumulate in stream networks?
Do impacts from forest harvesting spatially accumulate in stream networks?
by Kelli Charbonneau, Despite a suite of provincial guidelines working in concert with federal policy to promote sustainable forest management in Canada, legacies of ecosystem degradation from forestry persist, particularly within nearby streams. Harvesting-induced impacts to small headwaters tend to be well-studied and reasonably predictable, but it is lesser known how impacts manifest in larger downstream areas and if best management practices (BMPs) designed to protect against such impacts are effective at broader spatial scales. To address this uncertainty, I examined ecosystem indicators affected by selection-based harvesting under BMPs within mixed hardwood forest catchments along a spatial gradient (1st to 4th order streams, drainage areas 49 to 1856 ha). Indicators included water chemistry, dissolved organic matter (DOM) quality, sediment deposition and organic matter content, leaf litter decomposition and associated macroinvertebrate community structures, analysis of the algal contribution to stream consumer diet, and mercury (Hg) in water and biota. Indicator responses along the spatial gradient for streams within paired harvested and reference catchments were compared using two-factor ANOVAs. A significant interaction between treatment (reference vs. harvested) and sample site location (upstream, middle-reach, and downstream) was used as evidence for spatially cumulative trends within the harvested catchment (i.e., indicator response over spatial range differed in harvested catchment compared to reference catchment). A treatment effect with potential to have adverse implications at downstream sites in harvested catchments indicated that BMPs were not effective at preventing impacts at broader spatial scales. Overall, I found strong evidence for forest harvesting-induced spatially cumulative trends for % organic content of coarse sediment and various endpoints for Hg in water and biota. BMPs were effective at preventing an adverse impact from harvesting at downstream sites for all indicators except sediment deposition, % dietary algae, Hg(II) in biota, and bioaccumulation factor for MeHg in biota, but they were not effective at upstream sites (i.e., local spatial scale) for conductivity, total nitrogen, % organic content of sediment, % shredders, % dietary algae, and MeHg and Hg(II) in water and biota. My study contributes to a comprehensive and predictive understanding of the potential for spatially cumulative trends within harvested catchments, which is critical to help forest managers maintain healthy forest streams and their provisioning of aquatic ecosystem services for future generations of humans and wildlife alike.
Ecological forces structuring a soft-sediment community
Ecological forces structuring a soft-sediment community
by Travis G Gerwing, In a world undergoing rapid climate change, a greater understanding of the ecological interactions which structure our ecosystems may enable humans to predict, or even repair, anthropogenic changes upon our ecosystems. The Bay of Fundy, Canada, is an ideal system to investigate ecological interactions. Its moderate complexity of ecological factors makes it relatively easy to study, while high population densities, and replicate mudflats provide considerable investigational power. In this thesis, I explored biotic and abiotic factors that may structure the infaunal community of the intertidal mudflats in upper Bay of Fundy. I observed that winter stressors (e.g., ice presence and scour, air temperature, sediment hypoxia), as well as top-down predation, the input of resources in a system (bottom-up control), the activity of mesopredators (middle-out control), and sediment conditions were not exerting strong controlling influences upon this community. It seems likely that the infaunal community is predominantly structured by the arrival of individuals (larvae, juveniles and adults) into a site, and secondary movement (dispersal) of individuals post-settlement. Lastly, I utilized molecular scatology and next-generation sequencing to investigate the diet of one of the main top-down predators of this system, Semipalmated Sandpipers (Calidris pusilla). I observed that sandpipers were acting as generalists, foraging upon intertidal, pelagic, terrestrial, and freshwater prey items. Such a broad diet may explain why sandpiper predation was not exerting a strong controlling on the infaunal community. This diet information may alter the way we conserve this species, since current conservation efforts are directed towards beach and intertidal habitat. However, in light of the breadth of diet items observed here, conservation efforts may have to also include terrestrial and freshwater systems.
Ecological segregation between two closely related species: exploring Atlantic puffin and razorbill foraging hotspots.
Ecological segregation between two closely related species: exploring Atlantic puffin and razorbill foraging hotspots.
by Stephanie C. Symons, Threats to the marine environment are on the rise in the Bay of Fundy and the Gulf of Maine. Significant changes in marine food webs are already affecting the most important seabird breeding site in New Brunswick, Machias Seal Island. During the breeding season, this island is home to several seabird species, including regionally important colonies of Atlantic Puffins (Fratercula arctica) and Razorbills (Alca torda). These two auks coexist sympatrically during the breeding season, occupying similar dietary niches. Additionally, these birds are central place foragers, restricting their foraging ranges by the need to make several return trips (~10 per day) to feed their young or relieve their mate. In recent years, their food supply has deteriorated and there is concern for the future of auks in this region. Current knowledge of their at-sea distribution in the Bay of Fundy is especially fragmented, depending mainly on casual observations by passersby or the occasional survey. Until recently, GPS loggers providing fine scale data, were too large to deploy on any but the largest seabirds. Using a mix of GPS technology and direct observation of chick diet, I determined that puffins and razorbills avoid niche overlap by foraging in different places. Slight differences in diet and dive depth are likely consequences of foraging location. Despite detecting no differences in nest attendance, provisioning, and chick growth at the burrow-level, individual behavioural observations revealed that mates of individuals equipped with loggers provisioned significantly more than their tagged mate. These findings show that important tag effects can be overlooked with conventional methods.
Effect of substrate on settlement behaviour, development, growth, and survival of American lobster postlarvae, and evidence that mud bottom can serve as secondary nursery habitat
Effect of substrate on settlement behaviour, development, growth, and survival of American lobster postlarvae, and evidence that mud bottom can serve as secondary nursery habitat
by Kristin M. Dinning, Postlarval American lobsters, Homarus americanus, prefer settling onto a cobble substrate and delay settling onto other substrates. Using tanks lined with cobble, mud, or sand, I found that postlarvae settled first onto cobble, second onto mud, and last onto sand. Furthermore, postlarvae moulted sooner on cobble than on mud, and sooner on mud than on sand. The longest delay of settlement, over large, sand-lined tanks, resulted in reduced carapace length and mass at the next moult in comparison to postlarvae which settled earlier onto mud or cobble. The costs of delaying settlement could encourage settlement onto less-preferred substrates when cobble is unavailable. Accordingly, I deployed passive collectors onto mud habitat in Maces Bay, NB, Bay of Fundy. These collectors were colonized by juvenile lobsters ranging in size from young of the year up to adolescents. Consequently, I identify mud habitat as an overlooked nursery habitat for American lobster settlement and early life history.
Effect of wing tags and testing hypotheses of sexual size dimorphism in frigatebirds
Effect of wing tags and testing hypotheses of sexual size dimorphism in frigatebirds
by Sarah A. Hudson (nee Trefry), Sexual size dimorphism (SSD) is one of the most apparent and puzzling differences between males and females across many different taxa. This dissertation explores the evolution and maintenance of female-biased SSD (females larger than males) in Magnificent Frigatebirds (Fregata magn.ificens) breeding on Barbuda, in the eastern Caribbean. I tested two hypotheses to explain SSD. The first, the resource division hypothesis, implicates natural selection in the evolution of SSD through selection for reduced intersexual competition via trophic niche divergence. Using prey, stable isotope, and foraging location data, I tested specific predictions relating to larger female size. My results did not support the resource division hypothesis in frigatebirds, given the similarities in breeding season prey, stable isotope values, and foraging locations between males and females. A second hypothesis attempting to explain smaller male size is the aerial agility hypothesis, which proposes that smaller males have an advantage during mating displays or other aerial acrobatics. Wing traits affecting flight performance and predicted to be under selection were measured from breeding birds, and fledging success was used as a measure of fitness. Projection pursuit regression and cubic splines were used to explore the strength and shape of selection acting on wing traits, respectively. Male wing traits influencing manoeuvrability were under stronger selection than in females and correlated with nest volume, providing support for the aerial agility hypothesis maintaining small male size. This likely reflects the male's role in collecting nest material. Large female size may be a result of extended parental care relative to males, and requires further study. Because of low fledging success early in the study, I also conducted an experimental study and meta-analysis on the effects of wing tags, a common avian field marker. Wing tags had a significant negative effect on nest success in Magnificent Frigatebirds, and on survival and hatch and nest success in other birds. Based on these findings, I strongly recommend against the use of wing tags in future studies., Scanned from archival print submission.

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