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Made available in DSpace on 2014-06-11T19:30:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-25Bitstream added on 2014-06-13T20:21:14Z : No. of bitstreams: 1 batista_lfa_dr_prud.pdf: 2832429 bytes, checksum: 6a04247002ae8968fcab468a8a207011 (MD5) / Este trabalho propõe um modelo espaço-temporal para o desenvolvimento de macrófitas submersas no reservatório de Taquaruçu, rio Paranapenama, no município de Santo Inácio, estado do Paraná. A abordagem de construção do modelo é teórico-empírica, baseada em dados. O estudo da vegetação submersa é relevante pois a sua proliferação excessiva acarreta desequilíbrio ecológico e prejuízos econômicos para usinas hidrelétricas. Foram realizados dez levantamentos de campo no reservatório de Taquaruçu, rio Paranapenama. Utilizou-se a técnica hidroacústica para mapear a vegetação e a profundidade e foram adquiridas medidas limnológicas. A análise exploratória mostrou grande redução da infestação de 2009 para 2010, justificada pela intensa precipitação ocorrida no período. Constatou-se regiões de crescimento e decaimento da vegetação, heterogeneamente distribuídas no espaço e no tempo. O modelo gerado divide-se em: modelo pontual, determinístico, que descreve o crescimento vertical da vegetação, independente da vizinhança e modelo probabilístico, para estimar a propagação da vegetação em área. O modelo pontual foi baseado no modelo logístico, caracterizado pela curva sigmoidal. As variáveis utilizadas foram profundidade e coeficiente de atenuação. Os coeficientes do modelo foram calibrados com algoritmos genéticos, com a utilização de 18 pontos, coletados entre abril e agosto de 2010. Os dados de entrada deste modelo foram gerados com interpolação por krigeagem ordinária e resolução de 3 m. Na etapa de validação utilizou-se de 12 pontos, em que avaliou-se a estatística descritiva dos resíduos, índices de qualidade de ajustamento, análise gráfica da... / The focus of this work is to design a spatiotemporal model of submerged macrophyte development. The model developing approach is empirical, based on field data. The study of submerged vegetation is important due to its excessive proliferation, which causes ecological unbalance and economical losses to hydroelectric power plants. Ten field surveys were made in Taquaruçu reservoir, Paranapanema river. Hydroacoustic techniques were used to map the vegetation and depth, and limnological measurements were made. Exploratory analysis showed a great infestation reduction from 2009 to 2010, probably caused by the precipitation volume which occurred in that time. Macrophyte growth and decay regions were distributed in space and time in a heterogeneous way. The model produced is divided in: local model, deterministic, which describes the vertical vegetation growth, without neighborhood influence; and the probabilistic model, which estimates the macrophyte propagation in area. The local model was based on the logistic model whose curve is sigmoidal. The variables used were depth and attenuation coefficient. Model coefficients were calibrated with genetic algorithms, with 18 points collected between April and August 2010. Input data were generated with ordinary kriging interpolation and a resolution of 3 m. In the validation phase 12 points were used and descriptive statistics of residual... (Complete abstract click electronic access below)

The timing and composition of organic matter (OM) inputs to rivers are important as carbon plays a major role in river functioning. Management of Australian rivers since European settlement has altered inputs of organic matter to these systems. Heterotrophic microbes play a critical role in the transformation of OM in rivers, allowing transfer of carbon to other biota. Alteration to the proportions of OM from different sources affects microbial functioning due to differences in OM composition. Macrophytes can represent important sources of carbon to rivers, however their inputs and in-stream processing are poorly understood. The aim of my study was to examine inputs and microbial processing of macrophyte OM in Australian lowland rivers under different flows. Distributions of dominant macrophytes (Typha orientalis, Phragmites australis, Vallisneria gigantea and Persicaria prostrata) were mapped in three lowland river reaches in south eastern Australia. Integration with flow data in a GIS allowed the determination of macrophyte inundation patterns under different flows. Resource allocation (biomass and nutrients), live and dead shoot densities and litter production were monitored in the field over 18 months. DOM release from different macrophyte tissues was examined in the laboratory and leachate composition was assessed using nutrient and spectral analyses. Responses of riverine microbial communities to different OM sources were assessed from substrate-induced respiration and enzyme activity experiments and field measurements of respiration and enzymatic responses to varied OM inputs. Finally, all data were integrated into a model of microbial responses to macrophyte OM inputs induced by different flows. Large populations of macrophytes occurred at all three sites, at bed level, on in-channel benches and on banks. Bank slope, channel heterogeneity and the vertical distribution of macrophyte beds all affected macrophyte inundation patterns. Substantial differences in biomass allocation, nutrient dynamics and litter composition were observed among different plant growth forms and over time. While leaves represented the major shoot component in litter for all species, stems and reproductive structures were also important in some species. Aside from the litter pool, translocation to rhizomes represented a major sink for annual production in emergent plants. Patterns of shoot density and litter production over time varied among species, providing a source of variation for particulate, and hence dissolved OM inputs upon inundation. The majority of DOM release from POM occurred within 24 hours of inundation. Growth form, tissue type (blade, stem, etc.) and status (live or dead) affected rates, quantities and composition of DOM release, with implications for microbial utilisation. Both overall activity and patterns of carbon utilisation in riverine microbes changed in response to altered OM inputs. Patterns of microbial carbon use were shown to be specific to the carbon source which induced them. Modelling showed that flow regulation had a major impact on OM inputs and microbial metabolism, through the effects of flow variability on macrophyte vertical distributions, macrophyte bed inundation and dilution. Positive relationships between discharge, DOM inputs and microbial metabolism were observed at the most highly regulated site (drought < current < historic < flood). While a similar pattern occurred at the less regulated site in terms of total loading, dilution effects resulted in a reversal of this trend on a reach volume basis. Microbial metabolism and DOM inputs were restricted to summer/autumn under regulated flows compared to a greater emphasis on winter/spring inputs and microbial activity under unregulated flows. Continual OM inputs during winter with pulsed inputs in spring under natural flows probably benefit larger, slow-growing macro-invertebrates. River regulation promotes pulsed macrophyte OM inputs during spring/summer, potentially favouring riverine microbial and zooplankton production, although at lower levels due to the overall reduction in OM inputs. The predictive model of macrophyte OM inputs and microbial responses developed throughout this thesis represents a major step forward in our understanding of macrophytemicrobe interactions and our ability to manage our river systems. This work has shown that flow manipulation can be used to influence macrophyte organic matter inputs to rivers and microbial responses, affecting whole stream metabolism and food web interactions.

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The goal of this work is to contribute to the understanding eutrophication in large rivers with a detailed study of the Grand River, an impacted river in highly agricultural and urbanized Southern Ontario. It focuses on the role of nitrogen (N) and phosphorus (P) in the distribution and abundance of benthic submersed macrophytes, which are important actors in river N and P cycles. Chapter 1 uses data from the Provincial Water Quality Monitoring Network to examine seasonal, long term and spatial patterns in total P (TP), soluble reactive P (SRP), nitrate and nitrite (NO3- + NO2-) and ammonium (NH4+). The monitoring of many sites in the Grand River began in 1965, and I examine data from the period from 1965 to 2009. The monitoring program began prior to the Canada-USA ban on the use of phosphate in detergents, which came into effect in 1973, and also before major improvements to municipal waste water treatment. The phosphate ban is analyzed as an example of a whole-system nutrient manipulation experiment, and the seasonal and long term response of the river system, from headwaters to mouth, is examined. TP and SRP declined over the monitoring period, with the greatest response found in TP, which declined by 120 µg/l/y immediately downstream of the of the watershed’s largest treatment plant in the years 1972-1975. Thereafter, TP and SRP continued to decline over most of the lower river, with rates of decline in nutrient concentration accelerating with distance from the wastewater treatment plants (WWTPs). NO3+NO2 increased during the monitoring period in the upper portion of the river with the highest increase of 158 µg-N/l/y observed in the 10 year period of 1975-1985. It did not change in response to WWTP upgrades that occurred in the early 1970s. WWTPs were a clear source of TP, SRP and NH4+ to the river system, but not NO3 +NO2 , and the continual increase in NO3 +NO2 was due to increases in diffuse sources. The seasonal and spatial data suggest that non-point sources of N and P dominate in the Grand River watershed. However, the largest WWTP in the region at Kitchener is an important source of nutrients, and was an especially large source of P prior to changes in detergent standards and wastewater treatment. The submersed macrophyte biomass in the Grand River was examined as a function of proximity to WWTPs in chapter 2. Spatial surveys were conducted in 2007 and 2009 on three reaches of approximately 10 km in length each, with two reaches having an upstream and downstream section, separated by a WWTP. Macrophyte patches were mapped, biomass was estimated, and plants were analyzed for N and P. Tissue N and P were compared to published thresholds for evidence of nutrient limitation. Biomass was greater downstream of the WWTPs than upstream in both reaches and both years, indicating that nutrient loading leads to increased biomass downstream, evidence that even in a heavily agricultural watershed, point sources have a demonstrable effect on macrophyte biomass. Depth was important in explaining some of the variation, while river width and orientation were not important. Even though macrophyte biomass was elevated downstream of the WWTPs, there was no strong evidence of N or P limitation upstream based on tissue concentrations and a laboratory determined critical nutrient threshold, and I hypothesize that the nutrient limitation affecting biomass occurs earlier in the growing season, before peak biomass. This suggests that the eutrophication process in rivers is distinct from that in lakes, and future work should view eutrophication in rivers in the context of seasonal succession. Drivers of seasonal and inter-annual variability in submersed macrophyte biomass were examined in chapter 3 with a multi-year, reach-scale spatial survey of three reaches near the WWTPs of Waterloo and Kitchener. Biomass differed among reaches, years and sites, and showed distinct seasonal patterns. The reach downstream of the WWTPs had the highest biomass, and peak biomass came soonest in the growing season, while the upstream reach had the smallest and latest peak biomass. Weather was significantly correlated to both the quantity and the time of the peak biomass, with higher temperatures associated with larger and earlier peak biomass and precipitation and higher flow associated with later and lower peak biomass. Therefore, the eutrophication response in rivers can depend on weather, and these drivers of variation should be accounted for when forecasting responses to future changes in nutrient loading. The effect of nitrogen discharged by WWTPs on the riverine submersed macrophyte community, and the suitability of macrophyte tissues as indicators of point source impact, were quantified in chapter 4 using δ15N as a tracer of WWTP effluent impact. Macrophytes and water for NO3- and NH4+ concentration and isotope analysis was collected by canoe along two 10 km reaches of the river, up and downstream of two WWTPs. Macrophytes incorporated effluent nitrogen into their tissues downstream of the WWTPs, using effluent NH4+ rather than NO3-. Impacts of the effluent on macrophytes can be traced as far as 10 km downstream, while daytime chemical evidence of the plume disappeared much sooner. The δ15N-NH4+ value rapidly increased downstream of the WWTP, changing in one instance from +13‰ to +31‰ over 1 km, with macrophyte δ15N values changing from +6‰ to +24‰ over 5 km, while δ15N- NO3- values showed no such change. These data lead to the conclusion that riverine submersed macrophytes record the influence of WWTP effluent, specifically effluent NH4+, but that using two end-member mixing models to determine N sources would be inappropriate in such dynamic environments. Nitrogen cycle processes such as nitrification and denitrification are influenced by dissolved oxygen (DO) and rapid transformations occur in environments with strong DO gradients. Because development of dense macrophyte beds in eutrophic rivers has the potential to greatly alter daily oxygen cycling, producing strong redox potentials, macrophytes could influence microbial nitrogen cycling. In Chapter 5, nitrogen uptake by macrophytes using a 15N-NH4+ tracer and N2O production was investigated using in situ chamber incubations upstream and downstream of a WWTP. NH4+ uptake occurred in chambers, while measurable net N2O production occurred in some chambers only. Neither N2O production nor NH4+ uptake differed between chambers with and without PO43- addition, nor did they differ between light and dark treatments. NH4+ uptake was higher at the upstream site, indicating that above the WWTP there was NH4+ demand in the macrophyte community. NH4+ uptake was a hyperbolic function of mean chamber NH4+ concentration. Turnover time for the macrophyte N pool due to NH4+ uptake was as long as 47 d, while the turnover of the dissolved NH4+ pool was as rapid as 14 h. Because net uptake was a small fraction of gross uptake, calculated release rates were almost as high as uptake rates, again indicating rapid NH4+ cycling. Eutrophication of rivers has elements that make it a process distinct from that in lakes. I showed that, in the Grand River, N and P were both high in concentration throughout the river, with a distinct increase downstream of the largest WWTPs in the watershed. The biomass of benthic submersed macrophytes was elevated below the WWTPs, but there was no evidence of nutrient limitation upstream during the time of peak biomass. Macrophyte biomass development followed a seasonal pattern, but was also influenced by seasonal temperature and precipitation patterns. Thus, the riverine eutrophication process has an important seasonal component, much as the plants themselves do, peaking in the summer and senescing in the fall. As part of the eutrophication response, macrophytes altered the chemical cycles of nutrients that fuel their growth. Though changes in benthic biomass themselves are part of riverine eutrophication, this thesis provides evidence that changes in macrophyte biomass produces chemical and ecological changes that are characteristic of increased trophic conditions.

The goal of this work is to contribute to the understanding eutrophication in large rivers with a detailed study of the Grand River, an impacted river in highly agricultural and urbanized Southern Ontario. It focuses on the role of nitrogen (N) and phosphorus (P) in the distribution and abundance of benthic submersed macrophytes, which are important actors in river N and P cycles. Chapter 1 uses data from the Provincial Water Quality Monitoring Network to examine seasonal, long term and spatial patterns in total P (TP), soluble reactive P (SRP), nitrate and nitrite (NO3- + NO2-) and ammonium (NH4+). The monitoring of many sites in the Grand River began in 1965, and I examine data from the period from 1965 to 2009. The monitoring program began prior to the Canada-USA ban on the use of phosphate in detergents, which came into effect in 1973, and also before major improvements to municipal waste water treatment. The phosphate ban is analyzed as an example of a whole-system nutrient manipulation experiment, and the seasonal and long term response of the river system, from headwaters to mouth, is examined. TP and SRP declined over the monitoring period, with the greatest response found in TP, which declined by 120 µg/l/y immediately downstream of the of the watershed’s largest treatment plant in the years 1972-1975. Thereafter, TP and SRP continued to decline over most of the lower river, with rates of decline in nutrient concentration accelerating with distance from the wastewater treatment plants (WWTPs). NO3+NO2 increased during the monitoring period in the upper portion of the river with the highest increase of 158 µg-N/l/y observed in the 10 year period of 1975-1985. It did not change in response to WWTP upgrades that occurred in the early 1970s. WWTPs were a clear source of TP, SRP and NH4+ to the river system, but not NO3 +NO2 , and the continual increase in NO3 +NO2 was due to increases in diffuse sources. The seasonal and spatial data suggest that non-point sources of N and P dominate in the Grand River watershed. However, the largest WWTP in the region at Kitchener is an important source of nutrients, and was an especially large source of P prior to changes in detergent standards and wastewater treatment. The submersed macrophyte biomass in the Grand River was examined as a function of proximity to WWTPs in chapter 2. Spatial surveys were conducted in 2007 and 2009 on three reaches of approximately 10 km in length each, with two reaches having an upstream and downstream section, separated by a WWTP. Macrophyte patches were mapped, biomass was estimated, and plants were analyzed for N and P. Tissue N and P were compared to published thresholds for evidence of nutrient limitation. Biomass was greater downstream of the WWTPs than upstream in both reaches and both years, indicating that nutrient loading leads to increased biomass downstream, evidence that even in a heavily agricultural watershed, point sources have a demonstrable effect on macrophyte biomass. Depth was important in explaining some of the variation, while river width and orientation were not important. Even though macrophyte biomass was elevated downstream of the WWTPs, there was no strong evidence of N or P limitation upstream based on tissue concentrations and a laboratory determined critical nutrient threshold, and I hypothesize that the nutrient limitation affecting biomass occurs earlier in the growing season, before peak biomass. This suggests that the eutrophication process in rivers is distinct from that in lakes, and future work should view eutrophication in rivers in the context of seasonal succession. Drivers of seasonal and inter-annual variability in submersed macrophyte biomass were examined in chapter 3 with a multi-year, reach-scale spatial survey of three reaches near the WWTPs of Waterloo and Kitchener. Biomass differed among reaches, years and sites, and showed distinct seasonal patterns. The reach downstream of the WWTPs had the highest biomass, and peak biomass came soonest in the growing season, while the upstream reach had the smallest and latest peak biomass. Weather was significantly correlated to both the quantity and the time of the peak biomass, with higher temperatures associated with larger and earlier peak biomass and precipitation and higher flow associated with later and lower peak biomass. Therefore, the eutrophication response in rivers can depend on weather, and these drivers of variation should be accounted for when forecasting responses to future changes in nutrient loading. The effect of nitrogen discharged by WWTPs on the riverine submersed macrophyte community, and the suitability of macrophyte tissues as indicators of point source impact, were quantified in chapter 4 using δ15N as a tracer of WWTP effluent impact. Macrophytes and water for NO3- and NH4+ concentration and isotope analysis was collected by canoe along two 10 km reaches of the river, up and downstream of two WWTPs. Macrophytes incorporated effluent nitrogen into their tissues downstream of the WWTPs, using effluent NH4+ rather than NO3-. Impacts of the effluent on macrophytes can be traced as far as 10 km downstream, while daytime chemical evidence of the plume disappeared much sooner. The δ15N-NH4+ value rapidly increased downstream of the WWTP, changing in one instance from +13‰ to +31‰ over 1 km, with macrophyte δ15N values changing from +6‰ to +24‰ over 5 km, while δ15N- NO3- values showed no such change. These data lead to the conclusion that riverine submersed macrophytes record the influence of WWTP effluent, specifically effluent NH4+, but that using two end-member mixing models to determine N sources would be inappropriate in such dynamic environments. Nitrogen cycle processes such as nitrification and denitrification are influenced by dissolved oxygen (DO) and rapid transformations occur in environments with strong DO gradients. Because development of dense macrophyte beds in eutrophic rivers has the potential to greatly alter daily oxygen cycling, producing strong redox potentials, macrophytes could influence microbial nitrogen cycling. In Chapter 5, nitrogen uptake by macrophytes using a 15N-NH4+ tracer and N2O production was investigated using in situ chamber incubations upstream and downstream of a WWTP. NH4+ uptake occurred in chambers, while measurable net N2O production occurred in some chambers only. Neither N2O production nor NH4+ uptake differed between chambers with and without PO43- addition, nor did they differ between light and dark treatments. NH4+ uptake was higher at the upstream site, indicating that above the WWTP there was NH4+ demand in the macrophyte community. NH4+ uptake was a hyperbolic function of mean chamber NH4+ concentration. Turnover time for the macrophyte N pool due to NH4+ uptake was as long as 47 d, while the turnover of the dissolved NH4+ pool was as rapid as 14 h. Because net uptake was a small fraction of gross uptake, calculated release rates were almost as high as uptake rates, again indicating rapid NH4+ cycling. Eutrophication of rivers has elements that make it a process distinct from that in lakes. I showed that, in the Grand River, N and P were both high in concentration throughout the river, with a distinct increase downstream of the largest WWTPs in the watershed. The biomass of benthic submersed macrophytes was elevated below the WWTPs, but there was no evidence of nutrient limitation upstream during the time of peak biomass. Macrophyte biomass development followed a seasonal pattern, but was also influenced by seasonal temperature and precipitation patterns. Thus, the riverine eutrophication process has an important seasonal component, much as the plants themselves do, peaking in the summer and senescing in the fall. As part of the eutrophication response, macrophytes altered the chemical cycles of nutrients that fuel their growth. Though changes in benthic biomass themselves are part of riverine eutrophication, this thesis provides evidence that changes in macrophyte biomass produces chemical and ecological changes that are characteristic of increased trophic conditions.

Secondary salinisation has affected large areas of inland southwestern Australia, and in particular, low lying aquatic areas; causing the loss of freshwater submerged macrophyte communities and their replacement by salt-tolerant species. At high salinities, the salt-tolerant macrophyte-dominated ecological regime may be replaced by a regime dominated by benthic microbial communities, further reducing the structural and functional diversity of salinised wetland ecosystems. There is little prospect of restoring salinised systems to a freshwater state, meaning that saline macrophyte dominated wetlands have a heightened structural and functional importance in this landscape. Prior to this study, little was known about the drivers for change from one ecological regime to another in salinising wetlands or about rates of ecosystem response to these drivers. This study used experimental and observational data from seven saline wetlands in order to identify some of the potential mechanisms for the transition between the salt tolerant submerged macrophyte-dominated regime and the benthic microbial community-dominated regime. The applicability of existing conceptual models for ecological regime shifts was then tested against these data. Some of the mechanisms responsible for the formation and maintenance of the macrophyte-dominated regime were explored by examining the effects of salinity on germination and flowering in a series of salt-tolerant submerged macrophytes. The initiation and dominance of benthic microbial communities over a range of salinity and wetting regimes was also examined. The results suggested that macrophyte communities are unlikely to develop in seasonally-drying wetlands at high salinities (>45 ppt), but will usually germinate and establish well at lower salinities. It was also predicted that although benthic microbial communities can survive and grow across a wide range of salinities, they are likely to be outcompeted at low salinities by macrophytes or by phytoplankton blooms if water column nutrient levels are high. However, water permanence may facilitate benthic microbial community dominance. Existing conceptual models of ecological regime transitions, such as the alternative regimes model, did not account for the effect of water regime on the dynamics of seasonally-drying systems. Therefore, a new conceptual model incorporating the interaction between hydrology and salinity in seasonally-drying wetlands was proposed.

Orientador: Nilton Nobuhiro Imai / Coorientador: Edivaldo Domingues Velini / Banca: Tiago Garcia de Senna Carneiro / Banca: Thiago Sanna Freire Silva / Banca: Robinson Antonio Pitelli / Banca: Messias Meneguette Júnior / Resumo: Este trabalho propõe um modelo espaço-temporal para o desenvolvimento de macrófitas submersas no reservatório de Taquaruçu, rio Paranapenama, no município de Santo Inácio, estado do Paraná. A abordagem de construção do modelo é teórico-empírica, baseada em dados. O estudo da vegetação submersa é relevante pois a sua proliferação excessiva acarreta desequilíbrio ecológico e prejuízos econômicos para usinas hidrelétricas. Foram realizados dez levantamentos de campo no reservatório de Taquaruçu, rio Paranapenama. Utilizou-se a técnica hidroacústica para mapear a vegetação e a profundidade e foram adquiridas medidas limnológicas. A análise exploratória mostrou grande redução da infestação de 2009 para 2010, justificada pela intensa precipitação ocorrida no período. Constatou-se regiões de crescimento e decaimento da vegetação, heterogeneamente distribuídas no espaço e no tempo. O modelo gerado divide-se em: modelo pontual, determinístico, que descreve o crescimento vertical da vegetação, independente da vizinhança e modelo probabilístico, para estimar a propagação da vegetação em área. O modelo pontual foi baseado no modelo logístico, caracterizado pela curva sigmoidal. As variáveis utilizadas foram profundidade e coeficiente de atenuação. Os coeficientes do modelo foram calibrados com algoritmos genéticos, com a utilização de 18 pontos, coletados entre abril e agosto de 2010. Os dados de entrada deste modelo foram gerados com interpolação por krigeagem ordinária e resolução de 3 m. Na etapa de validação utilizou-se de 12 pontos, em que avaliou-se a estatística descritiva dos resíduos, índices de qualidade de ajustamento, análise gráfica da... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The focus of this work is to design a spatiotemporal model of submerged macrophyte development. The model developing approach is empirical, based on field data. The study of submerged vegetation is important due to its excessive proliferation, which causes ecological unbalance and economical losses to hydroelectric power plants. Ten field surveys were made in Taquaruçu reservoir, Paranapanema river. Hydroacoustic techniques were used to map the vegetation and depth, and limnological measurements were made. Exploratory analysis showed a great infestation reduction from 2009 to 2010, probably caused by the precipitation volume which occurred in that time. Macrophyte growth and decay regions were distributed in space and time in a heterogeneous way. The model produced is divided in: local model, deterministic, which describes the vertical vegetation growth, without neighborhood influence; and the probabilistic model, which estimates the macrophyte propagation in area. The local model was based on the logistic model whose curve is sigmoidal. The variables used were depth and attenuation coefficient. Model coefficients were calibrated with genetic algorithms, with 18 points collected between April and August 2010. Input data were generated with ordinary kriging interpolation and a resolution of 3 m. In the validation phase 12 points were used and descriptive statistics of residual... (Complete abstract click electronic access below) / Doutor

As anthropogenically-forced ocean temperatures continue to rise, the physiological response of marine macrophytes becomes exceedingly relevant. The Red Sea is a semi-isolated sea- the warmest in the world (SST up to 34°C) - already exhibiting signs of rapid warming rates exceeding those of other tropical oceans. This will have profound effects on the physiology of marine organisms, specifically marine macrophytes, which have direct influence on the dynamic carbonate system of the Red Sea. The aim of this paper is to define the physiological capability and thermal optima and limits of six ecologically important Red Sea macrophytes- ranging from seagrasses to calcifying and non-calcifying algae- and to describe the effects of increasing thermal stress on the performance and limits of each macrophyte in terms of activation energy. Of the species considered, Halophila stipulacae, Halimeda optunia, Halimeda monile and Padina pavonica thrive in thermal extremes and may be more successful in future Red Sea warming scenarios. Specifically, Halimeda opuntia increased productivity and calcification rates up to 38°C, making it the most thermally resilient macrophyte. Halophila stipulacae is the most productive seagrass, and hence has the greatest positive effect on Omega saturation state and offers chemical buffer capacity to future ocean acidification.

Coastal wetlands of Georgian Bay have been virtually ignored by ecologists until recently, when these ecosystems were found to have exceptionally high biodiversity compared to other Gr,~at Lakes wetlands. To address this deficiency, we conducted a baseline survey (2002 to 2007) to determine the biotic and abiotic characteristics of 92 wetlands in 18 quatemary watersheds, using a suite of published ecological indices developed specifically for coastal wetlands (Water Quality Index (WQI); adjusted Wetland Macrophyte Index (WMiadj), and the Wetland Fish IndexBasinPAex (WFIBasinPAex)). Although a majority of the watersheds are located in remote eastern and northern parts of the Bay and therefore receive minimal human disturbance, one watershed, Sturgeon River, located in southern Georgian Bay receives relatively high urban, recreational and agricultural disturbance. Mean scores of WQI and WMiadj varied significantly across the watersheds, ranging from 0.48 to 2.15, and from 2.29 to 3.77, respectively. Mean WFIBasinPAex scores, however, were less variable and only ranged from 3.53 to 3.86. Of the 88 macrophyte species identified, the most common were hardstem bulrush. (Schoenoplectus acutus), water celery (Vallisneria americana), richardson's pondweed (Potamogeton richardsonii), slender waternymph (Najasjlexilis) and Canadian waterweed (Elodea canadensis). Six non-native macrophytes, Purple loosestrife (Lythrum wlicaria), narrow-leaf cattail (Typha angustifolia), hybrid cattail (Typha x glauca), Eurasian milfoil (Myriophyllum spicatum), curly pondweed (Potamogeton crispw) and frogbit (Hydrocharus morsus-ranae) were also recorded, the most common ofwhieh was Eurasian milfoil. Sago pondweed (Stuckenia pectinata), a native species that can be invasive, and is tolerant of poor water-quality, was present in about half of the watersheds. Ofthe 51 fish species, pumpkinseed (Lepomis gibbosus) bluntnose minnow (Pfmephales notatus), brown bullhead (Ameiurus nebulosus), rock bass (Ambloplites rupestris), and yellow perch (Percajlavescens) were the most widespread and abundant. Three non-native species, common carp (Cyprinus carpio), alewife (Alosa pesudoharengus), and round goby (Neogobius melanostomus) were present but not dominant. WMI scores were highly correlated with WQI scores, and as expected, wetlands in the most disturbed southern watershed were associated with the lowest WQI and WM[ scores, and had the greatest number of exotic species. However, WMI scores of wetlands in a few exposed sites located at the tip of the Bruce Peninsula were similarly low, even though these sites are not yet impacted by human activities. There was no significant relationship between WFIBasinPAand WQI scores, although the WFIBasin PA did not seem to be affected by exposure. We recommend that the WQI and WMiadj be used in long-term monitoring programs of Georgian Bay to track negative impacts of human disturbance on these valuable ecosystems. / Thesis / Master of Science (MS)