We hypothesized that populations exposed to chronic levels of genotoxins for many generations in situ will accumulate latent heritable genetic damage leading to increases in mutational load and decreased population fitness. Common pulmonate snails (Lymnaea stagnalis) were collected from three sites that differed in pollution level [Manitoulin Island (reference), Beauharnois (moderate pollution), and Varennes (highly polluted)]. These organisms have a rapid generation time and are capable of self-fertilization. Fitness indicators were clutch size, survival (hatching to day 30) and growth (length from hatching to day 90). Recessive deleterious mutations that have accumulated through time are masked as snails preferentially outcrossed, but are expressed when snails self-fertilize. Results obtained by comparing fitness components of snails derived from selfing and outcrossing experiments showed that in sites with higher levels of pollution inbreeding depression increased for clutch size and survival. Results for growth rate were similar to those for clutch size and survival in the two least polluted sites, but not for the most polluted site, due possibly to biased mortality of smaller snails at this site. After correction for size biased mortality, the growth estimates showed patterns similar for the two polluted sites when compared to the reference site. This study suggests that long-term in situ exposure to genotoxic pollution may effect population fitness due to the accumulation of latent heritable genetic damage.

Approximately 10,000 tones of Hg are deposited annually as a result of anthropogenic activities. This increased Hg burden is known to have adverse neurological and reproductive effects on Common loons. A positive correlation between mercury (Hg) and selenium (Se) has been reported to exist in marine mammals and various species of marine and aquatic piscivorous birds. It has been hypothesized that the Hg/Se interactions may involve in the multiple mechanisms of Hg detoxification. This study focused on the suggested Hg/Se complex that forms in association with specific proteins. Specifically, this project focuses on the nature of these interactions in different tissues from wild Common loons (Gavia immer) that have been collected by the Canadian Wildlife Service. The Hg and Se concentrations in the various tissues were quantified using AAS. MALDI-TOF-MS and protein sequencing characterized the nature of the Hg/Se complex binding protein. Among the tissues, the liver had the highest concentrations of Hg and Se followed by kidney; muscle and brain. A strong association between Hg and Se was found in liver, kidney and eggs whereas there was no association in muscle and brain. In contrast brain and muscle had highest percentage of organic Hg suggesting that only inorganic Hg is associated with Se. Two Hg-Se binding protein complexes were found in liver both in the 15,200-15,300 Da range while one such complex in the same weight range was found in kidneys, when sequenced it was found that these proteins were the alpha A chain of Hemoglobin. The protein complex found in eggs was unique and although it was impossible to fully sequence it, it represents an unknown protein. The role of Se in Hg toxicity in eggs warrants further study.

Maternal colonies of the big brown bat, Eptesicus fuscus were studied in Delaware and Grant Counties from 21 May to 22 September, 1992. Nineteen colonies of bats were located and revisited several times during the summer. Bats were captured, sexed, aged, weighed and banded at each site. The weight gain pattern of the bats was related to rainfall and temperature during the summer. Other factors that might affect weight gain such as ectoparasites, tooth wear, and wing damage were also measured.The summer of 1992 had below normal rainfall in May and above normal rainfall in June and July. Temperatures were below normal during the study period. The weights of captured bats were compared to weights of bats captured at similar colonies during the same period in 1988, a dry year, and 1989 a wet year. Both of these years had near normal temperatures. Lower weight gain for juveniles and for adult females in late spring and early summer of 1992 was associated with higher than average precipitation and lower than average temperatures during the period. / Department of Biology

Spatial distribution of species and thus the composition of deciduous forests are expected to change in response to global climatic warming. Climate-growth response algorithms in forest simulation models that represent the influence of climate on tree growth are based on the geographic range limits of a species. These models assume that temperature limitations control the latitudinal range boundaries for tree species in the eastern United States, and that water limitations control the western range boundary. This study investigated spatial variation of tree-growth responses to historical variations in climate using tree-ring data for Quercus rubra L. from 71 study sites across latitudinal and longitudinal temperature and precipitation gradients in eastern North America. Correlation analyses were used to identify significant site-specific associations between radial growth indices and 130 climate variables for the common time interval 1930-1980. Geographic information systems (GIS), and Mantel and partial Mantel spatial correlation analyses were used to map, identify, and measure spatial associations between oak sensitivity to climate and regional climate patterns to test the hypothesis that climate controls the spatial distributions of species range limits.Seasonal climate variables exhibited the strongest correlations with radial growth most consistently across the 71 study sites. However, spatial patterns in regional climate were only weakly associated with spatial variation in red oak sensitivity to climate variables. Contrary to expectations, correlations between red oak radial growth indices and temperature variables at northern and southern sites were not significant, failing to support the hypothesis that latitudinal range limits are defined by temperature effects on mature tree growth. High early growing season temperature reduced growth mostly at sites in the southwest region, which concomitantly experienced high inter-annual variability in soil moisture. Increased early growing season site water balance and precipitation was associated with greater radial growth in the western third of red oak's range, partially supporting the hypothesis that the western range limit is defined by limited water availability. These results indicate that climate only partially determines range limit locations; thus model projections may exaggerate forest responses to climate change. / Department of Biology

The effect of lake acidification was evaluated, in the field, in terms of its impact on both the structural and functional composition of the macrozoobenthic community. The littoral macrozoobenthic community and water chemistry of 45 Canadian Shield lakes was sampled. The water chemistry variables sampled included pH, total dissolved calcium, conductivity, and dissolved organic acid (measured as colour). Partial canonical correlation analysis and partial regression analysis were used to identify those components of the macrozoobenthic community that most directly reflected pH variability. This was done by first removing from the data that portion of the variability attributable to total dissolved calcium, conductivity, and dissolved organic acids. In addition, the spatial structure in the data was removed by identifying the geographic coordinates of the sampling sites. / In general, the results presented here are not consistent with previous studies where the response of the macrozoobenthic community was related to pH without consideration of confounding covariables. Snails, leeches, mayflies and crayfish have all been cited for their sensitivity to acidification. The present study found these taxa to reflect, not pH variability, but rather attributes of water hardness. Similar results were found for both total zoobenthic biomass and functional feeding group abundance.

White blood cell phagocytosis was investigated and used with avian blood, and assessed as a potential biomarker for mercury immunotoxicity in free ranging birds (common loons). Phagocytosis is an essential immunological function and can be measured using flow cytometry. The assay was assessed with in vitro exposure using whole blood and isolated white blood cells (WBC) from domestic chickens, and with in vivo exposure using whole blood from captive doves and wild loons. McHg at 0.1ppm significantly depressed phagocytic capacity of isolated WBCs without affecting their viability, but did not affect phagocytic activity when added to whole blood up to 50ppm. Also, no significant relationship between blood-Hg level and phagocytic capacity of WBCs was observed in ringed turtle doves fed McHg in their diets, nor in wild common loons having a range of blood-Hg concentrations. The phagocytosis assay is a convenient assay for use in field studies of free-living birds, but is not responsive to McHg exposure in birds, and so is not recommended as a biomarker of immunotoxicity in Hg-exposed loons.

No description available.

Bibliography: leaves 105-121. / viii, 133, [28] leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis tests the hypothesis that plant strategies to respond to seasonal flooding can be used to predict their tolerance to variation in water regime. The studies illustrate contrasting strategies for survival in seasonally fluctuation water levels. These are tested in the field against similar species. Plants are surveyed at four stages of flooding at Bool Lagoon. The morphologically plastic species, V. reniformis and Triglochin procerum, respond to flooding with taller shoots and increased investment in photosynthetic tissue. It is concluded that the reproductive effort is much lower in the field than in the pond experiments, and changes in the population density of both species are not related to water regime. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1997?

Bibliography: leaves 105-121. / viii, 133, [28] leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis tests the hypothesis that plant strategies to respond to seasonal flooding can be used to predict their tolerance to variation in water regime. The studies illustrate contrasting strategies for survival in seasonally fluctuation water levels. These are tested in the field against similar species. Plants are surveyed at four stages of flooding at Bool Lagoon. The morphologically plastic species, V. reniformis and Triglochin procerum, respond to flooding with taller shoots and increased investment in photosynthetic tissue. It is concluded that the reproductive effort is much lower in the field than in the pond experiments, and changes in the population density of both species are not related to water regime. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1997?

No description available.