Aquaponics has the potential to be a superior food production method compared to traditional agriculture through its potential for sustainability. This is particularly important in advanced aquaponic systems that integrate waste disposal (e.g., kitchen waste) and involve several steps linking waste decomposition to protein production. In such systems a success of one type of organism propagates down the food chain and may have negative impact on contribution of other organisms, which reduces system efficiency. I hypothesised that a combination of top-down and bottom-up regulations, concepts borrowed from resilient natural ecosystems, would allow to optimize environment for aquaponics systems to avoid such negative impacts. First, I conducted an experiment using simplified systems with two trophic levels only to determine productivity, resistance and resilience of the various combinations of top-down and bottom-up forces. The simple systems contained algae and Daphnia magna and were placed under a light removal disturbance to observe the abilities of these different combinations to resist and recover from a generic negative environmental impact. Next, a similar light disturbance was implemented on a large complex aquaponics system to discover if it would react differently from the smaller ones. The resistance and resilience of algae in the small systems was not found to have any relationship to predation. The resilience of algae was better at low nutrient levels compared to high ones. There was evidence that low nutrient treatments had better resistance and resilience of abiotic factors. The larger systems appeared to have inferior resistance and resilience as compared to the simple, small systems. However, a time series analysis indicates that these large systems, in contrast to the simpler systems, actually improved in the amount of algae after the disturbance. New methods for accounting for this in resilience calculations are needed to eliminate potential statistical artifacts that might lead to some of my observations. / Thesis / Master of Science (MSc) / Aquaponics has the potential to be a superior food production method compared to traditional agriculture through its potential for sustainability. This is particularly important in advanced aquaponic systems that integrate waste disposal (e.g., kitchen waste) and involve several steps linking waste decomposition to protein production. In such systems a success of one type of organism propagates down the food chain and may have negative impact on contribution of other organisms, which reduces system efficiency. I hypothesised that a combination of top-down and bottom-up regulations, concepts borrowed from resilient natural ecosystems, would allow to optimize environment for aquaponics systems to avoid such negative impacts. First, I conducted an experiment using simplified systems with two trophic levels only to determine productivity, resistance and resilience of the various combinations of top-down and bottom-up forces. The simple systems contained algae and Daphnia magna and were placed under a light removal disturbance to observe the abilities of these different combinations to resist and recover from a generic negative environmental impact. Next, a similar light disturbance was implemented on a large complex aquaponics system to discover if it would react differently from the smaller ones. The resistance and resilience of algae in the small systems was not found to have any relationship to predation. The resilience of algae was better at low nutrient levels compared to high ones. There was evidence that low nutrient treatments had better resistance and resilience of abiotic factors. The larger systems appeared to have inferior resistance and resilience as compared to the simple, small systems. However, a time series analysis indicates that these large systems, in contrast to the simpler systems, actually improved in the amount of algae after the disturbance. New methods for accounting for this in resilience calculations are needed to eliminate potential statistical artifacts that might lead to some of my observations.

The toxicity of the metals: Cd, Cu, Pb, Ni, and Zn to the freshwater aquatic larvae of the midge fly Chironomus riparius was investigated using 24 h waterborne exposures. Even at the most sensitive life stage, first instar, the chironomids were extremely metal tolerant, with LC50 values for all metals being orders of magnitudes above both the CCME Canadian water quality guidelines for the protection of aquatic life, and the USEP A Water Quality Criteria. This high tolerance of C. riparius to metal toxicity, combined with an exceptional ability to accumulate and tolerate high internal metal burdens makes the chironomid an ideal organism to use in studies on factors affecting the trophic transfer of Cd. Zebrafish were fed with Cd-contaminated chironomids for 7 days, followed by 3 days of gut clearance with clean chironomids. Chironomids loaded with Cd by exposure to Cd-contaminated sediments exhibited a significantly higher trophic transfer efficiency (TTE) than did zebrafish 1 fed chironomids contaminated with Cd by waterborne exposure, although in both cases the TTE's were low (<2%). The majority ofCd transferred to zebrafish was stored in the gut and carcass, irrespective of ingestion of a natural diet (chironomids loaded with Cd), or a manufactured pellet diet of identical Cd concentrations. On a tissue concentration basis, the highest tissue accumulations in zebrafish were (in decreasing order): kidney> gut> liver> gill> carcass; this accumulation pattern w;ls also independent of concentration of Cd in the diet or of prey exposure route. Subcellular fractionation of chironomids found most of the Cd in the metal rich granule fraction followed by the organelle fraction. It also revealed that sediment exposed chironomids had significantly more Cd in the metallothionein-like protein fraction, and significantly less Cd in the cellular debris fraction than water-borne exposed chironomids, although these fractions accounted for only a small percent (~7%) of the total accumulated Cd. Despite this difference in prey subcellular fractionation, the subcellular storage of Cd in zebrafish fed on sediment-exposed chironomids and zebrafish fed on water-borne exposed chironomids was the same, with the highest accumulations in the organelles, enzymes, and metal rich granules fractions. Main areas of subcellular storage in zebrafish fed on a manufactured pellet food were identical to those ofzebrafish fed on chironomids. However, zebrafish fed on chironomids had significantly more Cd in the metallothionein-like protein fraction (5-10%) than did zebrafish fed on pellets :o%). Overall, TTE's were independent of concentration, but were dependent on route of prey exposure. Tissue-specific accumulations and tissue-specific distributions in zebrafish were independent of both concentration and route of prey exposure, and the gut consistently accounted for the highest proportion of overall body burden, and had the highest accumulation of all tissues; verifying its importance in preventing the internalization of Cd. Subcellular distributions were also independent of concentration, although zebrafish fed a biological food (chironomids) had more Cd in the metallothionein-like protein fraction than zebrafish fed a manufactured food. This has biological implications for Cd detoxification. / Thesis / Candidate in Philosophy

The adipose-derived stromal vascular fraction (SVF) is a promising new therapy for equine flexor tendonitis. This heterogeneous population of cells may improve tendon healing via the production of growth and chemotactic factors capable of recruiting endogenous stem cells and increasing extracellular matrix production by tendon fibroblasts (TFBL). The purpose of this study was to evaluate the ability of adipose-derived cells (ADC) culture expanded from the SVF to act as trophic mediators in vitro. We hypothesized that ADCs would produce growth and chemotactic factors important in tendon healing and capable of inducing cell migration and matrix protein gene expression. Superficial digital flexor tendons and adipose tissue were harvested from eight adult horses and processed to obtain SVF cells, ADCs and TFBLs. Adipose-derived cells and TFBLs were grown in monolayer culture for growth factor quantification, to produce conditioned media for microchemotaxis, and in co-culture for quantification of matrix protein gene expression by TFBLs. Growth factor gene expression by SVF cells was significantly greater than in ADCs or TFBLs. Co-culture of TFBLs and ADCs resulted in modest up-regulation of matrix protein expression (collagen types I and III, decorin, and cartilage oligomeric matrix protein) by TFBLs. Media conditioned by ADCs induced ADC migration in a dose dependent manner. These findings support the role of both SVF and ADCs as trophic mediators in tendon regeneration. The differences detected in gene expression between SVF cells and ADCs indicate that additional studies are needed to evaluate the changes that occur during culture of these cells. / Master of Science

Submitted by Edineia Teixeira (edineia.teixeira@unioeste.br) on 2018-03-05T18:57:19Z No. of bitstreams: 2 Andre _Xavier2016.pdf: 898699 bytes, checksum: d75d5de091bdf6639454359b01d27f0a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-03-05T18:57:19Z (GMT). No. of bitstreams: 2 Andre _Xavier2016.pdf: 898699 bytes, checksum: d75d5de091bdf6639454359b01d27f0a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-04-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Trophic relationships are central themes in ecology, and the interaction between predators and prey is one of the main topics addressed on the balance of relationships. These questions are very discussed associated with impacted environments with differentiated characteristics such as hydroelectric plant reservoirs, whose damming affects the forms of trophic interactions of the remaining post-dam species. About the interactions of predation, it is known that some abiotic factors such as temperature and water transparency participate in the mediation of foraging, which may favor predatory success and increases in the proportion of predators in relation to prey. For this reason, considering that excessive increases of predators may threaten the trophic balance of communities, as well as environmental exclusions presented by impacted systems such as reservoirs, this study evaluated through logistic models, if during a period of 36 months thermal elevations and visibility Of the water corresponded to increases in the proportion of piscivorous fish in relation to non piscivorous fish, taking as reference 17 neotropical reservoirs. The results showed an increase of about 14% in the proportion of piscivorous when correlated to higher values of temperature and transparency acting together, indicating that small positive changes in these variables may be sufficient to increase the proportion of these predators. The discussions focused on the relationships between environmental variables and predatory events. / Relações tróficas fazem parte de temas centrais em ecologia, e a interação entre predadores e presas é um dos principais assuntos abordados acerca do equilíbrio destas relações. Estas questões são bastante discutidas associando ambientes impactados e de características exclusivas como os reservatórios de usinas hidrelétricas, cujo represamento afeta as formas de interações tróficas das espécies remanescentes pós-barragem. Sobre as interações de predação, sabe-se que alguns fatores abióticos como a temperatura e transparência da água participam na mediação do forrageio, podendo favorecer sucesso predatório e aumentos na proporção de predadores em relação às presas. Por esta razão, considerando que aumentos excessivos de predadores possam ameaçar o equilíbrio trófico das comunidades, bem como exclusividades ambientais apresentadas por sistemas impactados como reservatórios, este estudo avaliou através de modelos logísticos, se durante um período de 36 meses as elevações térmicas e na visibilidade da água corresponderam a aumentos na proporção de peixes piscívoros em relação aos não piscívoros, tomando como referência 17 reservatórios neotropicais. Os resultados constataram aumento de cerca de 14% na proporção dos piscívoros quando correlacionada aos valores mais elevados de temperatura e transparência atuando em conjunto, evidenciando que pequenas alterações positivas nestas variáveis podem ser suficientes ao aumento da proporção destes predadores. As discussões focaram-se às relações entre as variáveis ambientais e eventos predatórios.

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The close proximity of net-pen salmon farms and wild Pacific salmon stocks in British Columbia (BC) is an incentive for precautionary management of the environmentally and economically damaging parasites known as sea lice. Bivalves cultured as part of an integrated multi-trophic aquaculture (IMTA) system may contribute natural, preventative louse control through the ingestion of planktonic sea lice larvae. A field trial was conducted to test sea lice mitigation by bivalves at a commercial Atlantic salmon (Salmo salar) farm in BC using Pacific oysters (Crassostrea gigas). Oysters were cultured in trays around one end of the farm and at a reference site approximately 150 m away from August 2013 until August 2014. Parasitic and planktonic sea lice (Lepeophtheirus salmonis and Caligus clemensi) were monitored before and during oyster deployment, beginning in December 2012. Parasite abundance peaked in January 2013 (6.5 lice/fish, >85% C. clemensi), and the following year in February 2014 (3.3 lice/fish, >80% L. salmonis). Larval density within cages peaked in January, both in 2013 (1.28 larvae/m3) and 2014 (0.96 larvae/m3). Parasite abundance was significantly correlated with both surface salinity (r2= 0.28, p=0.04) and sea lice larval density (r2= 0.65, p=0.01). Observed densities were significantly lower (t=3.41, p=0.009) than those calculated for the site based on water temperature and salinity, the number of adult female lice present, and the approximate number of fish. Sea lice mitigation by oysters was assessed by comparing monthly sea lice larval densities inside bivalve and non-bivalve fish cages, and by analyzing preserved oyster digestive tracts from January 2014 (when larval densities were highest) for presence of L. salmonis DNA using PCR. Using these methods, no significant evidence of sea lice mitigation was detected. Oyster growth was monitored by measuring whole wet weight, soft tissue wet, dry, and ash-free dry weight, and shell length, width, and height approximately every four months. Oysters were sampled equally across different sides of the farm and at the reference site (~150 m away from the farm) at three depths: 1, 3, and 6 m. All seven measurements increased significantly over time. Effects of side and depth varied by growth parameter; in general, oysters at 1 and 3 m were significantly larger than those at 6 m, and oysters cultured at the reference site were either significantly smaller or the same size as those cultured around the farm. Oysters from select sides were consistently, significantly larger than those from other sides and from the reference site. Overall, the findings suggest that sea lice larvae quickly dispersed away from the farm after hatching and were not significantly impacted by bivalve presence around the fish cages. Bivalves grew significantly larger over time and size was significantly impacted by both depth and side of the fish cage. While no evidence of larval sea lice reduction/ingestion by cultured bivalves was detected, this study provides information on all sea lice stages present throughout an Atlantic salmon production cycle, as well as the first detailed growth analysis of Pacific oysters cultured alongside farmed Atlantic salmon in BC. / Graduate / 0792 / byrneaa@gmail.com

The Saskatchewan River Delta (SRD) in central Canada, North America’s largest inland delta, is an important spring and fall stopover site for waterfowl with thousands flocking there annually to stage. However there is very little information on their origins prior to arrival and their feeding ecology while in the Delta. To date, band recoveries are largely from birds banded south of the SRD, mostly due to limited banding activity in productive waterfowl habitats to the north such as the Peace-Athabasca Delta and the broader boreal forest. There is also very little information on the importance of the SRD as an overall recruitment area for the North American waterfowl population. No studies have used stable isotopes to infer the origins and diets of these birds. I first used stable isotopes of hydrogen (2H) and sulfur (34S) to infer migratory origins and specifically evaluate the contribution of local and non-local birds to the staging population in the SRD during fall migration. Based on 2H, I found that few birds (34%) originated in the SRD despite its known role as breeding habitat; instead, most birds (56%) were migrants from the north of the SRD and a small fraction (10%) came from south of the SRD. Stable sulfur isotope data proved a useful tool in further delineation of birds into prairie and forest regions, respectively. Secondly, I used stable carbon (13C) and nitrogen (15N) isotopes and mercury concentrations in liver tissue ([Hg]) to trace nutrient sources of these waterfowl using the SRD prior to fall migration, and tested for differences in diets among species, sexes and age groups within species. I demonstrated the importance of macrophytes as a source of food, particularly among the American Widgeon and Northern Pintail (70% of the diet). However, there was some level of partitioning of resources at the species level, as Blue-winged Teal and Green-winged Teal used invertebrate sources, as did a distinct group of Mallards. This is likely a result of birds minimizing competition for resources during the short staging period in the SRD when waterfowl densities are high. Finally, I found that 15N values in liver, a known indicator of trophic position, can be confounded by variation in basal sources; hence, there is the need to use other isotopes or tracers such as [Hg] for verification. Overall, my results suggest an important role for northern ecosystems in central Canada in contributing to the waterfowl breeding population in the Central Flyway, and a key role for the SRD in providing fuel for waterfowl during fall migration. .

Fall cankerworm (FCW) outbreaks have recently increased in frequency and intensity in the mid-Atlantic region of the United States, especially around cities of Charlotte, NC and Richmond, VA. This study evaluated the effects of two landscape features associated with urbanization, impervious surface and forest cover, on population patterns of FCW and its parasitoids across eastern Virginia. Forest cover was positively related to parasitism rates while impervious surface was positively related to FCW abundance, suggesting that FCW outbreaks may be amplified in urban areas. FCW abundance declined over the two-year period of this study, but parasitism rate increased at most sites. Parasitism was highest at sites that experienced FCW outbreaks first, indicating that parasitoid populations are responding to moth abundances. It remains to be seen whether this outbreak was an aberrant occurrence, or represents a regime shift to more frequent defoliation in Virginia, similar to that in North Carolina urban areas.

Arthropod predators often use prey and conspecific cues to make foraging decisions. Calosoma wilcoxi (Leconte) is a voracious predatory beetle that specializes on lepidopteran larvae often found in the forest canopy, including the fall cankerworm. This study tested the hypothesis that C. wilcoxi uses olfactory cues to detect prey and conspecifics. A Y-tube olfactometer was used to test attractiveness to larvae, larval frass, conspecific cues, and volatiles from herbivore-damaged white oak leaves. C. wilcoxi did not preferentially choose the treatment in any of the experiments. There was no difference in mean time spent in the treatment or control arm for any of the cues assayed. The time to choose the treatment was significantly shorter in the female conspecific experiment only. I found no evidence that C. wilcoxi uses olfaction to locate prey; however, C. wilcoxi is attracted to conspecifics. C. wilcoxi may use conspecific cues to make informed foraging decisions.

The British Isles have been invaded by 12 alien cynipid gallwasps over the past 150 years. The first 4 of these species have been studied in depth and represent a model system in phytophagous insect community structure. In this thesis, I extend this research programme to incorporate 8 further invaders. I examine recent changes in the distribution of invading oak gallwasps in Britain and spatial patterns in the composition of the associated communities of phytophagous cynipid inquilines and parasitoids. I use fully quantitative webs to assess the diversity and strength of trophic interactions between native and invading species and assess the potential for apparent competition between gallwasps mediated by shared natural enemies. Of the first 4 invaders to be studied, 3 have expanded their range since 1991/2. Three of these 4 species are now well established in Scotland, while Andricus corruptrix remains confined to England. Four new invaders (A. aries, A. lucidus, A. grossulariae, Aphelonyx cerricola) are established in southern England and are spreading. Rates of range expansion vary across species (between means of 3.3 and 24.4 km per year), and may be correlated with variation in lifecycles and abundance. The four newest invaders (Neuroterus saliens, Plagiotrochus australis, P. coriaceus, P. quercusilicis) are currently restricted to their sites of first record. Previous studies on one of the early invaders, Andricus quercuscalicis, identified south to north and east to west declines in community species richness and in the abundance of specific parasitoid species. I find that: 1) Parasitoid associations with the asexual galls of A. quercuscalicis track inquiline recruitment to this host. 2) The longitudinal and latitudinal gradients in parasitoid species richness demonstrated in previous work are no longer apparent, suggesting that younger northern communities may be converging on their older southern counterparts. 3) Inquilines show increasing survivorship with distance from the original centre of their distribution in south east England, suggesting at least temporary exploitation of enemy-free space. 4) The recently invading Andricus and Aphelonyx species have all rapidly recruited parasitoids and inquilines. Fully quantitative webs were constructed for 4 sites in England and Scotland incorporating both native and invading cynipids. I tested the hypothesis that newly arriving gallwasp generations would fall within food web compartments based on their host oaks and location on the tree as demonstrated in previous work. Counter to this hypothesis, parasitoids attacking one of the newest invaders (A. grossulariae) break down host tree-associated compartmentalisation. Where A. grossulariae has yet to become established, host-based compartmentalisation remains pronounced. Despite extensive sharing of parasitoid species, I found only one strong indirect interaction between species (both aliens) and no evidence for widespread apparent competition. Spatial density dependent predation on an appropriate scale can stabilise population dynamics. I quantified predation by blue tits (Parus caeruleus) of spring generation bud galls on Turkey oak (Q. cerris) at three spatial scales (shoots within branches, branches within trees, trees within sites). I found significant levels of bird predation, with most variation occurring between trees rather than between shoots within branches. Spatial density dependence was detected at sites in southern England, primarily at the level of trees within a site. Relationships at finer spatial scales were far more variable in magnitude and sign. My results suggest that blue tits forage primarily at the level of trees. This thesis presents comprehensive new data on the establishment and spread of 12 invading cynipid species and on their interactions with native communities. The results further understanding of both spatial and temporal aspects of natural enemy recruitment to invading species. In particular, it is clear that individual invading species can significantly modify trophic linkage between established food web compartments. Finally, my data emphasise the significant (but often unstudied) contribution of highly mobile vertebrate predators to otherwise closed ecological microcosms.