• Taste responsiveness and beer behaviour

      Small-Kelly, Stephanie; Department of Biological Sciences
      Orosensory perception strongly influences food and beverage liking and consumption. Variation in the perception of these oral sensations presents an opportunity to conceptualise and commercialise products based on consumers’ taste responsiveness. This thesis investigates the role of orosensory responsiveness in alcoholic beverage behaviour. Specifically, examining the role of thermal tasting in beer and cider liking and consumption. 60 participants (31 thermal tasters (TTs) and 29 thermal non-tasters (TnTs) rated the intensity of aqueous solutions of beer- and cider- relevant tastants: iso-α-acid (bitterness), ethanol (irritation, bitterness, sweetness), dextrose (sweetness) and citric acid (sourness) at concentrations typically found in commercial beers on generalised labelled magnitude scales (gLMS). Taste intensities (gLMS) and liking (9-point hedonic scale) of eight beer and cider samples differing in iso-α-acid and ethanol content were also rated. Participants self-reported on their beer and cider consumption. They also rated the importance of select factors when purchasing beer. TTs experienced the bitterness of ethanol more intensely than did TnTs (p(t)<0.05), they also rated the bitterness, sourness, astringency, and overall taste intensity of sampled beers and ciders higher than TnTs (p(F)<0.05). Agglomerative hierarchical and k-means clustering of liking scores revealed 3 clusters of consumers, characterized as ‘bitter dislikers’, ‘beer likers’, and ‘alcohol lovers’. ‘Taste’ was the most important factor consumers used when purchasing beer. It can be concluded that thermal taster status is an important determinant in the perception of beer and cider flavour. These results should assist product developers in designing beers and ciders targeted for specific segments of the population.
    • Temporal variation in the coral reefs of the east coast of the inner gulf of Thailand

      Poosuwan, Chon.; Department of Biological Sciences (Brock University, 1998-07-09)
      A series of permanent line transects established on fourteen reefs on the eastern seaboard of the Gulf of Thailand were monitored through a three-year period (1995- 1998) using a video transect method. Hierarchical cluster analysis shows three distinctive reef community types dominated by 1) Porites, 2) Acropora and 3) zoantharians. The reefs are developed under naturally turbid conditions and relatively low salinity due to the proximity of four major river outlets located in the uppermost area of the gulf. The number of Acroporid species on the reefs is positively correlated with distance from the major flver outlets. Eighty-seven species of scleractinian coral were found on the transects. Over the three-year period, the comparison of 1995-97-98 matched stations using Repeated Measures ANOV A reveals no significant time-dependent change in percent area cover of reef components except for an overall significant reduction in the faviid coral component. In the 1997-98 matched station comparison, statistical tests reveal significant increases in both Acropora and Porites components that translated into an overall increase in total living coral cover. These findings indicate that the overall environmental conditions have been favorable for coral growth. Outcompetition of massive corals by faster growing corals on several reefs also indicates conditions favorable for reef expansion. Growth of newlyformed Porites colonies over primary rock substrate and dead coral skeleton was presumably responsible for its rapid increase. Although these reefs are in an area of rapid industrialization and population growth, resultant anthropogenic effects have not yet stopped active coral accretion.
    • Testosterone’s regulation of the HPA axis differs for adolescent and adult male rats

      Zeidan, Mostafa; Department of Biological Sciences
      Stress hormones such as corticosterone (CORT), enables rodents to cope and meet the demands of their environment. In adult male rats, CORT release in response to stressors is dampened by the gonadal hormone testosterone. Adolescent male rats secrete more CORT in response to stressors than do adults and our lab has previously reported that gonadectomised pre-pubertal adolescent male rats (postnatal day [P] 35) do not show the dampening effect of testosterone replacement on CORT release in response to restraint stress found in adult rats (postnatal day [P] 75); whereas, post-pubertal adolescent rats (postnatal day [P] 45) show heightened CORT release when given testosterone replacement. Therefore, the main question would be what is the basis of the age difference in response to testosterone? And so, my mechanistic hypothesis that is tested in the thesis is that the greater stress response of adolescents than adults is because of greater conversion of testosterone to estradiol and/or less conversion of testosterone to DHT in adolescents than in adults. In Experiment 1, I replicated the results for P45 and P75 male rats. In Experiment 2, rats were gonadectomised (GDX) and given implants of testosterone, dihydrotestosterone (DHT), or empty, control implants (CTL) and plasma was obtained after 30 minutes of restraint. Although no significant differences were obtained for CORT levels, the pattern of means was consistent with our previous findings. Further, DHT and testosterone-treated rats had lower vasopressin (AVP) and corticotrophin releasing hormone (CRH), and a trend toward lower aromatase-immunoreactive cell counts in the parvocellular paraventricular nucleus (PVN) than did CTL rats, irrespective of age, and there were no group differences in the magnocellular PVN. In Experiment 3, gonadally-intact P45 and P75 males were treated with fadrozole (aromatase inhibitor), finasteride (5a-reductase inhibitor), flutamide (androgen receptor antagonist), or vehicle (VEH). Higher CORT concentrations after restraint were found in P45 than in P75 only among VEH rats. Among P45 rats, CORT levels were higher in VEH than in fadrozole-treated rats only. Among P75 rats, VEH rats had lower CORT levels than did finasteride-treated rats. These results suggest that the higher stress release of CORT in P45 may involve greater conversion of testosterone to estradiol at the level of the adrenal cortex.
    • Thermal Preference and Habitat Use of Eastern Garter Snakes (Thamnophis sirtalis sirtalis) in a Southern Ontario Peatland

      Abney, Curtis; Department of Biological Sciences
      Garter snakes are the most widespread reptile in North America. Despite occupying vastly different biogeoclimatic zones across their range, evidence suggests that the thermal preference (Tsel) of garter snakes has not significantly diverged among populations or different Thamnophis species. The reason for garter snake’s wide thermal tolerance could lie in their flexible thermoregulatory behaviours and habitat use. I aimed to investigate this relationship by first identifying the Tsel of a common garter snake species (Thamnophis sirtalis sirtalis) via a thermal gradient in the lab. I used this Tsel parameter (27.82 – 32.15 ºC) as a benchmark for calculating the thermal quality of open, mixed, and forested habitats all used by the species. I measured the thermal profiles of these habitats by installing a series of operative temperature models that mimicked the thermal properties of living garter snakes and recorded environmental temperatures as living snakes experience them. Lastly, I used coverboards to survey the habitat usage of T. s. sirtalis. Of the three habitats, I found that the open habitat offered the highest thermal quality throughout the snake’s active season. In contrast, I recorded the greatest number of snakes using the mixed habitat which had considerably lower thermal quality. Although the open habitat offered the greatest thermal quality on average, environmental temperatures regularly exceeded the upper limits of the animals’ thermal tolerance, greatly restricting the activity window for Eastern garter snakes. Therefore, the open habitat may be less thermally attractive to T. s. sirtalis. My data show that not all habitat types used by Eastern garter snakes share the same quality and the relationship is not as simple as warm, open habitats are better. Rather, these animals may preferentially seek out areas that offer a mix of both open and closed-canopy spaces to suit their thermoregulatory needs. In conclusion, T. s. sirtalis may select more thermally stable habitats over those that present them with thermal extremes and greater constraints to their surface activity.
    • Thermoacclimatory variations in the activities of enzymes implicated in ion transport in the rainbow trout, salmo gairdneri

      McCarty, Lynn Scott.; Department of Biological Sciences (Brock University, 1977-07-09)
      Two groups of rainbow trout were acclimated to 20 , 100 , and 18 o C. Plasma sodium, potassium, and chloride levels were determined for both. One group was employed in the estimation of branchial and renal (Na+-K+)-stimulated, (HC0 3-)-stimulated, and CMg++)-dependent ATPase activities, while the other was used in the measurement of carbonic anhydrase activity in the blood, gill and kidney. Assays were conducted using two incubation temperature schemes. One provided for incubation of all preparations at a common temperature of 2S oC, a value equivalent to the upper incipient lethal level for this species. In the other procedure the preparations were incubated at the appropriate acclimation temperature of the sampled fish. Trout were able to maintain plasma sodium and chloride levels essentially constant over the temperature range employed. The different incubation temperature protocols produced different levels of activity, and, in some cases, contrary trends with respect to acclimation temperature. This information was discussed in relation to previous work on gill and kidney. The standing-gradient flow hypothesis was discussed with reference to the structure of the chloride cell, known thermallyinduced changes in ion uptake, and the enzyme activities obtained in this study. Modifications of the model of gill lon uptake suggested by Maetz (1971) were proposed; high and low temperature models resulting. In short, ion transport at the gill at low temperatures appears to involve sodium and chloride 2 uptake by heteroionic exchange mechanisms working in association w.lth ca.rbonlc anhydrase. G.l ll ( Na + -K + ) -ATPase and erythrocyte carbonic anhydrase seem to provide the supplemental uptake required at higher temperatures. It appears that the kidney is prominent in ion transport at low temperatures while the gill is more important at high temperatures. 3 Linear regression analyses involving weight, plasma ion levels, and enzyme activities indicated several trends, the most significant being the interrelationship observed between plasma sodium and chloride. This, and other data obtained in the study was considered in light of the theory that a link exists between plasma sodium and chloride regulatory mechanisms.
    • Thermoaclimatory variations in the microenvironment of hemoglobin in the rainbow trout, Salmo gairdneri and the carp, Cyprinus carpio

      Smeda, John Stanislaw.; Department of Biological Sciences (Brock University, 1978-07-09)
      Several inorganic substances (e.g., C£ , Mg , Ca , H ) are potent negative modulators of hemoglobin-oxygen affinity. To evaluate the possibility that potentially adaptive changes in the red cell ionic environment of hemoglobin may take place during acclimation of fishes to increased environmental temperature, hematological status (hemoglobin, hematocrit, red cell numbers, mean erythrocytic volume and hemoglobin content), plasma + + 2+ 2+ and packed red cell electrolyte levels (Na , K , Ca , Mg , C£ ) were evaluated in summer and winter populations of the stenothermal rainbow trout, Salmo gairdneri, following acclimation to 2°, 10°, 18°C, and in a spring population of eurythermal carp, Cyprinus carpio, held at 2°, 16° and 30°C. From these data cell ion concentrations and ion:hemoglobin ratios were estimated. In view of the role of red cell carbonic anhydrase in the reductions of blood C02 tensions and the recruitment of Na and C£~ lost by fishes, a preliminary investigation of thermoacclimatory changes in the activity of this system in rainbow trout erythrocytes was conducted. Few changes in hematological status were encountered following acclimation. There was, however, some evidence of weight-specific differential hematological response in carp. This lead to markedly greater increases in hemoglobin, hematocrit and red cell numbers in smaller rather than in larger specimens at higher temperatures; variations which were 2+ well correlated with changes in plasma Ca . Plasma composition in summer trout was not altered by acclimation. In winter trout plasma Na and K increased at higher temperatures. Carp were characterized by increases in plasma calcium, and reductions in sodium and magnesium under these conditions. Several significant seasonal differences in plasma ion levels were observed in the trout. (n) In trout, only erythrocytic K and K :Hb were altered by acclimation, rising at higher temperatures. In carp Na , Na :Hb, C£~ and C£~:Hb in- 2+ 2+ creased with temperature, while Mg and Mg :Hb declined. Changes in overall ionic composition in carp red cells were consistent with increases in H content. In both species significant reciprocal variations in C£~ 2+ - + and Mg were found. In mammalian systems increases in C£ and H reduce hemoglobin-oxygen affinity by interaction with hemoglobin. Reduction in 2+ 2+ Mg maximizes organophosphate modulator availability by decreasing ATP»Mg complex formation. Thus, the changes observed may be of adaptive value in reducing hemoglobin-oxygen affinity, and facilitating oxygen release to cells at higher temperatures. Trout appear to maintain a high chloridelow magnesium state over the entire thermal tolerance zone. Carp, however, achieved this state only at higher temperatures. In both species mean erythrocytic volume was decreased at higher temperatures and this may facilitate branchial oxygen loading. Since mean erythrocytic volume was inversely related to red cell ion content, it is hypothesized that reductions in cell volume are achieved by export of some unidentified solute or solutes. Variations in the carbonic anhydrase activity that could be attributed to the thermoacclimatory process were quite modest. On the other hand, assays performed at the temperature of acclimation showed a large temperature effect where under in vivo conditions of temperature fish acclimated to higher temperatures might be expected to have higher activities. Furthermore, since hematocrit increased with temperature in these fish, while carbonic anhydrase is present only in the erythrocyte, the whole blood levels of this enzyme are expected to increase and further augment the temperature effect. This, in turn, could aid in the reduction of C02 (111) tension and increase the production of H and HC0~~ used in the active uptake of Na and C£ at higher temperatures.
    • Timing of di-ammonium phosphate addition to fermenting chardonnay must : effect on nitrogen utilization, ethyl-carbamate formation, and CAR1 expression by yeast /

      Albert, Monique M. C.; Department of Biological Sciences (Brock University, 2002-05-21)
      The maximum amount of ethyl carbamate (EC), a known animal carcinogen produced by the reaction of urea and ethanol, allowed in alcoholic beverages is regulated by legislation in many countries. Wine yeast produce urea by the metabolism of arginine, the predominant assimilable amino acid in must. This action is due to arginase (encoded by CARl). Regulation of CARl, and other genes in this pathway, is often attributed to a well-documented phenomenon known as nitrogen catabolite repression. The effect of the timing of di-ammonium phosphate (DAP) additions on the nitrogen utilization, regulation of CARl, and EC production was investigated. A correlation was found between the timing of DAP addition and the utilization of nitrogen. When DAP was added earlier in the fermentations, less amino nitrogen and more ammonia nitrogen was sequestered from the media by the cells. It was also seen that early DAP addition led to more total nitrogen being used, with a maximal difference of ~25% between fermentations where no DAP was added versus addition at the start of the fermentation. The effect of the timing ofDAP addition on the expression of CARJ during fermentation was analyzed via northern transfer and the relative levels of CARl expression were determined. The trends in expression can be correlated to the nitrogen data and be used to partially explain differences in EC formation between the treatments. EC was quantified at the end of fermentation by GC/MS. In Montrachet yeast, a significant positive correlation was found between the timing of DAP addition, from early to late, and the final EC concentration m the wine (r = 0.9226). In one of the fermentations, EC levels of 30.5 ppb was foimd when DAP was added at the onset of fermentation. A twofold increase (69.5 ppb) was observed when DAP was added after 75% of the sugars were metabolized. When no DAP was added, the ethyl carbamate levels are comparable at a value of 38 ppb. In contrast, the timing of DAP additions do not affect the level EC produced by the yeast ECU 18 in this manner. The study of additional yeast strains shows that the effect of DAP addition to fermentations is strain dependent. Our results reveal the potential importance of the timing of DAP addition to grape must with respect to EC production, and the regulatory effect of DAP additions on the expression of genes in the pathway for arginine metabolism in certain wine yeast strains.
    • Transfection of newt blastema mesenchyme using the techniques of lipofection and direct gene transfer

      Lourenssen, Sandra.; Department of Biological Sciences (Brock University, 1992-07-09)
      The regenerating amphibian limb provides a useful system for studying genes involved in the establishment of positional information. While a number of candidate genes that may playa role in pattern formation have been identified, their function in vivo is unknown in this system. To better ascertain the role of these genes, it would be useful to be able to alter their normal patterns of expression in vivo and to assess the effects of this misexpression on limb pattern. In order to achieve this, a method of introducing a plasmid containing the eDNA of a gene of interest into a newt blastema (a growth zone of mesenchymal progenitor cells) is needed. Unfortunately, most commonly used transfection techniques cannot be used with newt blastema cells. In this study, I have used the techniques of lipofection and direct gene transfer to introduce plasmid DNA containing reporter genes into the cells of a regenerating newt limb. The technique of lipofection was most effective when the blastema cells were transfected in vitro. The optimal ratio for transfection was shown to be 1:3 DNA:Lipofectin (W/w) , and an increase in the amount of DNA present in the mixture (1:3 ratio maintained) resulted in a corresponding increase in gene expression. The technique of direct gene transfer was used to transfect newt blastema cells with and without prior complex formation with Lipofectin. Injection of plasmid DNA alone provided the most 3 promising results. It was possible to introduce plasmid DNA containing the reporter gene ~-galactosidase and achieve significant gene expression in cells associated with the injection site. In the future, it would be interesting to use this technique to inject plasmid DNA containing a gene which may have a role in pattern formation into specific areas of the newt blastema and to analyze the resulting limb pattern that emerges.
    • Trends in fish prey capture by common terns following zebra mussel invasion : do terns track fish species abundance? /

      Game, Rob F.; Department of Biological Sciences (Brock University, 1997-05-21)
      The Common Tern (Sterna hirundo) is a ground nesting colonial seabird. Terns rely primarily on small prey fishes which they obtain through plunge diving for their survival as well as the survival of their offspring during the breeding season. The zebra mussel (Dreissena polymorpha) is a small bivalve mollusk that invaded North American waters in the late 1980's. Through its suspension feeding, the zebra mussel has the ability to alter the entire aquatic ecosystem, ultimately leading to a reduction in pelagic organisms including small prey fish. The objective of the study was to determine what (if any) indirect effects the invasion of the zebra mussel has had on fish prey captured by terns. The study took place in two separate two-year periods, 1990-91 and 1995-96 on a concrete breakwall off the north shore of Lake Erie near Port Colborne, Ontario. Daily nest checks revealed clutch initiation dates, egg-laying chronology, hatching success and morphological egg characteristics (length and breadth). Behavioural observations included time each sex spent in attendance with its brood, the frequency of feeding chicks and the prey species composition and size fed to chicks as well as to females (courtship feeding). Egg sizes did not differ between study periods, nor did feeding rates to chicks, suggesting that food was not a limiting resource. Terns spent less time with their broods (more time foraging) in the 1995-96 period. However, they also had significantly larger broods and fledged more offspring. The time of each individual foraging trip decreased, suggesting that fish were easier to obtain in 1995 and 1996. Lastly, kleptoparasitism rates decreased, suggesting that the costs of foraging (time, energy) actually decreased as fewer birds adopted this strategy to compensate for what I assumed to be a lack of available food (fish). The only significant difference between the periods of 1990, 1991 and 1995, 1996 was a change in diet. Terns delivered significantly fewer rainbow smelt and more emerald shiner in 1995 and 1996. However, the average size of fish delivered did not change. Thus, there was little impact on prey captured by Common Terns in Lake Erie since the invasion of the zebra mussel.
    • An unusual postharvest spotting disease of the comercial mushroom, Agaricus bisporus, caused by a novel pathovar of Pseudomonas tolaasii

      Dobbin, Christine L.; Department of Biological Sciences (Brock University, 2001-11-04)
      An unusual postharvest spotting disease of the commercial mushroom, Agaricus bisporus, which was observed on a commercial mushroom farm in Ontario, was found to be caused by a novel pathovar of Pseudomonas tolaasii. Isolations from the discoloured lesions, on the mushroom pilei, revealed the presence of several different bacterial and fungal genera. The most frequently isolated genus being Pseudomonas bacteria. The most frequently isolated fungal genus was Penicillium. Of the bacteria and fungi assayed for pathogenicity to mushrooms, only Pseudomonas tolaasii was able to reproduce the postharvest spotting symptom. This symptom was typically reproduced 1 to 7 days postharvest, when mushroom pilei were inoculated with 101 to 105 cfu. Of the fungi tested for pathogenicity only a Penicillium sp. and Verticillium fungicola were shown to be pathogenic, however, neither produced the postharvest spotting symptom. The Pseudomonas tolaasii strain isolated from the postharvest lesions differed from a type culture (Pseudomonas tolaasii ATCC 33618) in the symptoms it produced on Agaricus bisporus pilei under the same conditions and at the same inoculum concentration. It was therefore designated a pathovar. This strain also differed from the type culture in its cellular protein profile. Neither the type culture, nor the mushroom pathogen was found to contain plasmid DNA. The presence of plasmid DNA is therefore not responsible for the difference in pathogenicity between the two strains.
    • Using GPS, GIS & remote sensing to understand Niagara Terroir

      Marciniak, Matthieu; Department of Biological Sciences (2012-03-30)
      The focus of this study was to detennine whether soil texture and composition variables were related to vine water status and both yield components and grape composition, and whether multispectral high definition airborne imagery could be used to segregate zones in vineyards to target fruit of highest quality for premium winemaking. The study took place on a 10-ha commercial Riesling vineyard at Thirty Bench Winemakers, in Beamsville (Ontario). Results showed that Soil moisture and leaf'l' were temporally stable and related to berry composition and remotely-sensed data. Remote-sensing, through the calculation of vegetation indices, was particularly useful to predict vine vigor, yield, fruit maturity as well as berry monoterpene concentration; it could also clearly assist in making wines that are more representative ofthe cultivar used, and also wines that are a reflection of a specific terroir, since calculated vegetation indices were highly correlated to typical Riesling.
    • Using GPS, GIS & remote sensing to understand Niagara Terroir : Pinot noir in the Four Mile Creek & St. David's Bench sub-appellations

      Ledderhof, David; Department of Biological Sciences (2012-03-30)
      The relationships between vine water status, soil texture, and vine size were observed in four Niagara, Ontario Pinot noir vineyards in 2008 and 2009. The vineyards were divided into water status zones using geographic information systems (GIS) software to map the seasonal mean midday leaf water potential (,P), and dormant pruning shoot weights following the 2008 season. Fruit was harvested from all sentinel vines, bulked by water status zones and made into wine. Sensory analysis included a multidimensional sorting (MDS) task and descriptive analysis (DA) of the 2008 wines. Airborne multispectral images, with a spatial resolution of 38 cm, were captured four times in 2008 and three times in 2009, with the final flights around veraison. A semi-automatic process was developed to extract NDVI from the images, and a masking procedure was identified to create a vine-only NDVI image. 2008 and 2009 were cooler and wetter than mean years, and the range of water status zones was narrow. Yield per vine, vine size, anthocyanins and phenols were the least consistent variables. Divided by water status or vine size, there were no variables with differences between zones in all four vineyards in either year. Wines were not different between water status zones in any chemical analysis, and HPLC revealed that there were no differences in individual anthocyanins or phenolic compounds between water status zones within the vineyard sites. There were some notable correlations between vineyard and grape composition variables, and spatial trends were observed to be qualitatively related for many of the variables. The MDS task revealed that wines from each vineyard were more affected by random fermentation effects than water status effects. This was confirmed by the DA; there were no differences between wines from the water status zones within vineyard sites for any attribute. Remotely sensed NDVI (normalized difference vegetation index) correlated reasonably well with a number of grape composition variables, as well as soil type. Resampling to a lower spatial resolution did not appreciably affect the strength of correlations, and corresponded to the information contained in the masked images, while maintaining the range of values of NDVI. This study showed that in cool climates, there is the potential for using precision viticulture techniques to understand the variability in vineyards, but the variable weather presents a challenge for understanding the driving forces of that variability.
    • Utilisation of Proximal Sensing Technology to Map Variability in Ontario Vineyards

      Kotsaki, Eleni; Department of Biological Sciences
      Precision agriculture is a term used to refer to a suite of technologies used for the optimisation of production in agronomic crops. The overall goal of this study was to determine whether high resolution proximally sensed observations acquired by the GreenSeeker™ technology could be correlated with soil moisture, vine water status, yield components and grape composition, and whether temporally consistent relationships could be established. The research was carried out on three experimental sites involving two Riesling, two Cabernet franc and two Pinot noir blocks throughout the Niagara Region of Ontario (Canada). A grid of geolocated sentinel vines was chosen for each vineyard block. Data were collected three times during the growing season between fruit set and veraison [soil moisture, leaf water potential (ψ)], at harvest (yield components, berry composition) and in winter [vine size, winter hardiness (LT50)]. GreenSeeker™ observations were likewise collected from lag phase to just prior to harvest, through the calculation of Normalized Difference Vegetation Index (NDVI). Thereafter, relationships between vine water status, yield components and berry composition variables as well as data from the GreenSeeker™ were validated. Overall, higher NDVI values were associated with yield components and vine size, while lower NDVI values were correlated with better berry composition, suggesting that GreenSeeker™ is a practical tool for vineyard vegetative growth surveys, and for grape composition inferences. Clustering associations were made through k-means statistical analysis in conjunction with Moran's I spatial autocorrelation index; soil moisture followed by the NDVI had the strongest clustering patterns. The outcomes from proximal sensing technology allow opportunities to stream and compliment present agricultural practices towards higher accuracy and efficacy by means of exploiting the observed variation.
    • The utility of sedimentary diatoms as a measure of historical lake ph

      Dixit, Sushil Sharan.; Department of Biological Sciences (Brock University, 1983-07-09)
      As a result of increased acid precipitation, the pH of a large number of Canadian Shield lakes has been falling. Prior to this study there was no documentation available to explain the history of lake acidification for the Algoma area lakes. In order to obtain this information the diatom inferred pH technique was developed in this study. During two field seasons, July 1981 and July 1982, short sediment cores (circa 25-30 cm) were collected from 28 study lakes located north of Lake Superior, District Algoma, Ontario. The surface sediment diatoms (0-1 cm) from each of these lakes were carefully identified, enumerated, and classified in terms of their pH indicator status. The surface sediment diatom analysis indicated that lake pH is one of the most important factors affecting the species composition and relative abundance of diatom populations. Thus diatom assemblages can be sensitive indicators of lake acidification. When Nygaard's index alpha was plotted against observed lake pH, a statistically significant relationship resulted (r=-0.89; p=<O.OI). The index alpha regression equation was used to construct the pH histories of 4 lakes (lakes X4, CS, U3, and WI). The repeatability of this technique was confirmed by comparing two downcore paleo-pH profiles of Lake WI. These two paleo-pH profiles represented almost identical paleo-pH patterns for Lake WI. The paleo-pH study of Lake X4 revealed that the lake has been rather acidic (pH <5.6) for the last 200 years. It appears that the recent increase in acid precipitation 3 over the last 30 years has not altered the water pH compared to the lake's pH history. However, the paleo-pH study of another acidic lake (Lake CS) indicated that its pH has significantl}* dropped over the last 30 years . During this time the Lake CS pH has dropped almost 2 pH units (7.1 to 5.2). The other two lakes studied for downcore pH were circumneutral in nature . One of these lakes (Lake U3) displayed a relatively stable pH history while the other lake (Lake WI) displayed significant pH fluctuations over post-Ambrosia time. The variable pH history of Lake WI was probably associated with the Algoma sintering plant plume and forest fires. A significant relationship between surface sediment diatoms and observed lake pH and secondly a statistically significant relationship between index alpha and observed pH suggested that diatoms are one of the best indicators of lake pH. Thus diatom inferred pH technique has great potential in explaining the rate of lake acidification.
    • Utilization of unmanned aerial vehicles and proximal sensing to detect Riesling vineyard variability

      Dorin, Briann; Department of Biological Sciences
      A single vineyard block can consist of significant spatial variability for several grape-growing attributes. The ability to detect and subsequently respond to this variation can lead to improved vineyard management, a growing practice termed precision viticulture. The overall goal of this research study was to determine if remote-sensing technologies could be used to detect Riesling vineyard variability, thus enhancing precision viticulture implementation. Approximately 80 grapevines in a grid pattern were geo-located within each of six commercial Riesling vineyards across the Niagara Peninsula in Ontario. From these grapevines the following variables were measured to determine their vineyard variation: soil and vine water status, vine size/vigor, winter hardiness, virus titer, yield components, and berry composition. Subsequently, remote-sensing technologies collected thermal [by unmanned aerial vehicle (UAV)] and multispectral (by UAV and ground-based proximal sensing technology GreenSeeker™) data from each block. Multispectral data were transformed into the Normalized Difference Vegetation Index (NDVI). Vineyard UAV NDVI maps were further used for selective harvesting of areas corresponding to low vs. high NDVI and wines made from these two zones were compared chemically and sensorially. The hypothesis was that remote and proximal sensing technologies could accurately detect vineyard variation for manually collected variables and further implicate differences in wine attributes upon zonal harvesting. Direct positive correlations were observed between remotely and proximally sensed NDVI vs. vine size, leaf stomatal conductance, leaf water potential, virus infection, yield, berry weight, and titratable acidity and inverse correlations with Brix and potentially-volatile terpene concentration. Maps created from remotely and proximally sensed data demonstrated similar spatial configurations to interpolated maps of these variables. In general, GreenSeeker NDVI demonstrated the most significant relationships with measured variables compared to UAV NDVI and UAV thermal data. Wines created from areas of low vs high NDVI differed inconsistently in their wine pH. Sensorially, in certain sites and vintages, panelists were able to distinguish between wines made from low vs high NDVI zones. Overall, remote sensing demonstrates the ability to detect vineyard areas differing in measures of vine health, size, yield, berry composition, and wine attributes, though more research is needed to understand the inconsistent results observed between vineyard sites and vintages.
    • Viability interactions between the left and right arms of the second chromosome of Drosophila melanogaster

      Pechan, Peter Alexander.; Department of Biological Sciences (Brock University, 1977-07-09)
      Inter and intrachromosomal viability interactions have been detected in a few experimental studies. Computer simulations and analytical models have led to postulation of nonadditivity of gene action. This study reports evidence of strong nonadditive interactions between the arms of the metacentric second chromosome of Drosophila melanogaster. Mean viability for 40 homozygous lines of the second chromosomes was 0.720+0.265 • Mean viability for 40 half homozygous second chromosomes was 0.928!O.)10 • Significant heterogeneity among and within lines was found in both groups of chromosomes, as well as a highly significant viability difference between the two groups. Comparison of observed viabilities with the expected values, according to the theories of additive and multi - plicative gene action. was made for both groups. Highly significant departures from the expected values were found for over 90% of the lines in both groups of chromosomes, for both additive and multiplicative models of gene action.
    • Water and electrolyte content and distribution in tissues of thermally-acclimated rainbow trout, Salmo gairdneri

      Mearow, Karen M.; Department of Biological Sciences (Brock University, 1978-07-09)
      The primary objective of this investigation was that of providing a comprehensive tissue-by-tissue assessment of water-electrolyte status in thermally-acclimated rainbow trout, Salmo gairdneri. To this end levels of water and the major ions, sodium, chloride and potassium were evaluated in the plasma, at three skeletal muscle sites, and in cardiac muscle, liver, spleen, gut and brain of animals acclimated to 2°, 10° and 18°C. The occurrence of possible seasonal variations in water-electrolyte balance was evaluated by sampling sununer and late fall-early winter populations of trout. On the basis of values for water and electrolyte content, estimates of extracellular and cellular phase volumes, cellular electrolyte concentrations and Nernst equilibrium potentials were made. Since accurate assessment of the extracellular phase volume is critical in the estimation of cellular electrolyte concentrations and parameters based on assumed cellular ion levels, [14 C]-polyethylene glycol-4000, which is assumed to be confined to the extracellular space, was employed to provide comparisons with various ion-defined spaces (H20~~s, H20~~/K and H20~~s). Subsequently, the ion-defined space yielding the most realistic estimate of extracellular phase volume for each tissue was used in cellular electrolyte calculations. Water and electrolyte content and distribution varied with temperature. Tissues, such as liver, spleen and brain appeared to be the most thermosensitive, whereas skeletal and cardiac muscle and gut tissue were less influenced. 'Summer' series trout appeared to be more capable of maintaining their water- electrolyte balance than the ~fall-winter' series animals. i The data are discussed in terms of their possible effect on maintenance of appropriate cellular metabolic and electrophysiological functions.
    • Water quality and fish populations of the Welland River, Ontario /

      Steele, Peter Owen.; Department of Biological Sciences (Brock University, 1981-06-15)
      The water quality and fish populations of the Welland River were observed to decline with distance downstream. This coincided with increased agricultural , domestic and industrial waste loadings. The river upstream of the City of Welland received considerable loadings from agricultural sources. Centrarchids, sciaenids, ictalurids, cyprinids and esocids characterized this upper section of the river. Most of these species were tolerant of low dissolved oxygen concentrations and the high turbidity which prevailed there . The river near Port Robinson receives many industrial and domestic wastes as evidenced by the water quality data. The fish in this section were less abundant and the observed population was comprised almost solely of cyprinids. Further downstream, near Montrose, the Welland River received shock loads of chemical wastes that exceeded a specific conductance of ISiOOO ;umhos/cm. Few fish were captured at this site and those that were captured were considered to be transients. A review of the literature revealed that none of the common indices of water quality in use today could adequately predict the observed distributions. In addition to the above, the long-term trend (l3 yrs) of water quality of the lower Welland River revealed a gradual improvement. The major factor thought to be responsible for this improvement was the operation of the Welland Sewage Treatment Plant. The construction of the New Welland Ship Canal coincided with large fluctuations of the total solids and other parameters downstream. These conditions prevailed for a maximum of three years (1972- 1975)' Furthermore, spawning times and temperatures, geographic distributions, length-weight regressions and many other descriptive aspects of the ecology of some 26 species/ taxa of fish were obtained. Several of these species are rare or new to southern Ontario.
    • X-ray diffraction studies of muscle : observations on the anterior byssus retractor muscle of Mytilus edulis and the insect flight muscle from Sarcophaga bullata

      Cottrell, Alan Philip.; Department of Biological Sciences (Brock University, 1977-07-09)
      The interfilament spacing of the anterior byssus retractor muscle from Mytilus edulis was studied as the muscle was extended. It was found that variations in this spacing were very small and consistent with the hypothesis that the interfilament spacing was independent of the extension of the muscle. It was observed that the interfilament spacing was dependent on the osmolarity of the bathing medium. In concentrated solutions of the artificial seawater, the interfilament spacing decreased; while in dilute solutions of artificial seawater, it was observed that the interfilament spacing was increasing. X-ray diffraction patterns were obtained from fresh, and glutaraldehyde fixed, specimens of insect flight muscle from Sarcophaga bullata. There patterns were in general agreement with previous X-ray diffraction studies of insect flight muscle. A reflexion G at 93A was observed and interpreted as arising from diffraction in the mitochondria. Specimens of dried insect flight muscle produced a diffraction pattern consisting of arc and ring reflexions. This was interpreted as suggesting an ordered arrangement of cristae, in the mitochondria from these muscles.