Metals are ubiquitous and naturally occurring; however, anthropogenic activities have elevated metal concentrations in river sediments above what would be expected naturally. One of the primary anthropogenic sources of metals in freshwater is contamination by mine tailings, a toxic slurry of waste rock and chemicals left over after ore minerals or coal extraction. Mining waste is most often stored in retention ponds, which sometimes leak or fail. One of the worst mine tailings disasters on record occurred on the Tisza River of Central Europe in the winter of 2000, releasing over 240,000 tons of mine tailings laced with metals into the natural environment. Elevated metals in freshwater can negatively affect fish and other aquatic organisms, raising concerns as to the long-term ecological consequences of the spill. Therefore, the objectives of this dissertation were to describe the ecological implications of metals pollution from mining on freshwater systems through an empirical case study of the Tisza River combined with controlled laboratory experiments of chronic cadmium exposure on a model species, channel catfish (Ictalurus punctatus). Specific research questions discussed in the following chapters include: (1.) What is the current distribution of metals in the lower Tisza River Basin and are metals transported from the main channel to floodplain habitats?; (2.) Is there evidence for bioaccumulation and/or trophic transfer of metals to fish in the Tisza?; (3.) What are angler’s perceptions and fish consumption risks in the lower Tisza river basin?; and (4.) What are the effects of sub-lethal exposure to cadmium on growth, development, metabolism, and stress response in a model fish species? The case study of the Tisza River Basin was conducted during early summer in 2013 and 2014. Water, sediment, and fish were collected from the Tisza River as well oxbow lakes along the lower basin. Samples were screened for metals via GF-AAS following standard methods. Additionally, we conducted interviews at each sampling location to determine fish consumption habits. Controlled laboratory exposures were conducted during summer of 2015. Eggs of channel catfish (Ictalurus punctatus) were fertilized in treatment water and raised to 6 month old fingerlings. Treatments of cadmium included concentrations of 0.5 µg L-1 (control), 2 L-1 (low) and 6 L-1 (high), with endpoints of growth, development, cellular stress, metabolism, and general stress response. Results indicate that lakes with the greatest connectivity trended toward elevated metals; however, chlorophyll a concentrations decreased suggesting dilution of nutrients from surrounding agriculture. River connectivity therefore increases ecosystem health of floodplain lakes by ameliorating eutrophication, but as a trade-off with potential contamination of metals. This may have implications for management strategies in the basin as fish from the oxbow lakes also trended toward higher concentrations of metals compared to the river main stem. Although we did not detect any indication that metals are biomagnifying through the fish community, fish are clearly taking up contaminants from the water and sediment. Additionally, although fish fillets generally fell below human consumption guidelines, surveys collected at field sites indicate disparities between health risks and perceptions of those risks. For example, many people believe that fish from the oxbow lakes present a lower risk for metals than the river main stem, converse to our findings. Exposure of channel catfish to cadmium concentrations similar to those observed in the Tisza Basin indicate that negative physiological effects, such as altered carbohydrate metabolism and subsequently growth, can occur in fish at muscle concentrations below consumption guidelines. Although cadmium in Tisza fish fillets were lower than expected, metals may still be problematic for the basin as they may disproportionately affect early life stages of fish. This could skew life histories of exposed populations compared to unaffected fish, potentially reducing growth rates, size at maturity, reproductive output, and lifespan; indicating the need for more paired field and laboratory assessments of chronic metals exposure.

Various aspects of the ecophysiology of rootless carnivorous Utricularia plants were assessed, with focus on nutrient acquisition and mutualistic interactions within trapping organs. The study includes extracellular enzyme measurements, the evaluation of commensal microbial community structure and function, stable isotope labelling to determine plant carbon allocation, and ion chromatography analyses of trap fluid composition

Acharadria crocea é um hidrozoário comum do Atlântico Sul-Ocidental. Na costa brasileira, a espécie possui um padrão de sazonalidade bem definido, sendo abundante nos meses frios do ano e ausente ou rara no verão e outono. Durante o inverno, a espécie apresenta intenso crescimento assexuado por brotamento, permitindo o rápido desenvolvimento da colônia. Esta se torna fértil em um curto espaço de tempo e produz uma grande quantidade de larvas, o que favorece o estabelecimento de novas colônias. Além destas características, a espécie já foi associada com transporte antrópico, por meio de incrustação em cascos de navios, o que a torna uma espécie potencialmente invasora. Este trabalho avaliou experimentalmente a tolerância ecofisiológica das larvas de A. crocea a temperatura e salinidade da água, bem como sua capacidade de colonização de diferentes substratos, tanto naturais (carapaças de cracas e mexilhões) como artificiais (fragmentos de PET e alumínio). A influência de um biofilme multiespecífico de bactérias no assentamento da espécie também foi analisada. Com base nos dados de tolerância ecofisiológica das larvas, foi realizada e modelagem de nicho da espécie utilizando GLM (Modelos Lineares Generalizados), que gerou mapas de sua distribuição potencial. Utilizando dados de ocorrência geográfica disponíveis na literatura, foram gerados também mapas de distribuição potencial das colônias adultas utilizando o algoritmo MAXENT. Para integrar as informações das fases bentônica e planctônica de A. crocea, foi realizada subsequentemente a intersecção dos mapas gerados por ambas as metodologias, gerando assim uma predição unificada de sua ocorrência. / Acharadria crocea is a common South-occidental Atlantic hydrozoan. On the Brazilian coast it presents a well defined seasonality pattern, being abundant on the cool months of the year and absent or rare on summer and autumn. During winter, the specie increases its numbers by asexual stolonal growth, as well as the colony size. The colony becomes fertile and produces a great amount of larvae, allowing the establishment of new colonies. Besides these characteristics, A. crocea was already found colonizing ship hulls, being considered a highly invasive species. This report experimentally evaluated the ecophysiological tolerance of A. crocea larvae to water temperature and salinity, as well as its ability to colonize different substrates, both natural (mussel and barnacle shells) and artificial (plastic bottles and aluminum). The influence of a bacterial film on its adaptation was also analyzed. Based on the ecophysiology of the larvae, an ecological niche modeling was built using GLM (generalized linear models) to create maps of the distribution of the larvae. Using literature based graphic occurrence data and the MAXENT algorithm, maps of the adult colonies potential distribution were also created. To relate information of benthonic and planctonic phases of A. crocea, an intersection of the maps was built from both methods.

A irrigação na citricultura ganhou grande importância nos últimos oito anos, devido à utilização de porta-enxertos menos tolerantes a seca. Hoje grande parte da citricultura irrigada é feita por gotejamento, sistema em que apenas uma porcentagem do sistema radicular recebe água. Esses pontos tornam de grande valia estudos relacionados às respostas das plantas submetidas a diferentes áreas molhadas de solo e também ao estresse hídrico. Esse trabalho foi conduzido com o objetivo de avaliar as respostas fisiológicas de lima ácida Tahiti a pequenas porcentagens de área molhada. Foi avaliada condutância estomática (gs), transpiração (T), temperatura foliar (Tf), potencial de água na folha (), teor de clorofila e produtividade e qualidade de frutos. O experimento foi conduzido na fazenda Areão ESALQ/USP, Piracicaba, SP, em um pomar de 1ha de lima ácida Tahiti (Citrus latifolia Tanaka) enxertadas em citromelo Swingle (Poncitrus trifoliata (L.) x Citrus paradisi Macf.) no espaçamento 7x4m e irrigados por gotejamento. Para leituras de condutância estomática e transpiração foi utilizado um porômetro de equilíbrio dinâmico e balanço nulo LI-COR 1600 (Licor, Inc., Lincoln, EUA). Para temperatura da folha foi utilizado um termômetro de infravermelho (Scantenp). Para determinação de potencial de água na folha foi utilizado uma camâra de Scholander (Modelo 3005 Soil Mosture Equipament Co., Santa Bárbara, CA, EUA), e para determinação do teor de clorofila foi utilizado o um clorofiLOG (Falker). A avaliação de qualidade de frutos foi feita seguindo as metodologias propostas por Bleinroth et al. (1976). As diferentes porcentagens de área molhada foram dadas por diferentes números e tipos de gotejadores, de forma a aplicar sempre a mesma lâmina de irrigação. Os resultados mostraram que não houve diferença significativa entre os tratamentos para gs, T, e Tf, porém Tf foi sempre superior a temperatura do ar, podendo ser um indicador de deficiência hídrica. Quanto ao potencial hídrico das folhas, o tratamento não irrigado apresentou menores valores em relação aos tratamentos de maior área irrigada. O tratamento não irrigado também apresentou menores teores de clorofila, principalmente o teor de clorofila b, na face sul (mais sombreada). A produção e qualidade de frutos não apresentaram diferenças significativas. / The irrigation in citrus gained great importance in the last eight years, due to the use of rootstocks less tolerant to drought. Currently, much of the citrus is irrigated by drip irrigation system, where only a percentage of the root system receives water. These items make great value for studies related to the responses of plants subjected to different áreas of wet soil and also to water stress. This study aimed to evaluate the physiological responses of Tahiti lime fruit a small percentage of wetted area. Was evaluated stomatal conductance (gs), transpiration (T), leaf temperture (Tf), the leaf water potential (), chlorophyll content and productivity and quality of fruit. The experiment was conducted at the farm Areão ESALQ/USP, Piracicaba, Brazil, in a orchard of 1 ha of Tahit lime fruit (Citrus latifolia Tanaka) grafted in a citromelo Swingle (Poncitrus trifoliata (L.) x Citrus paradise Macf.) in a spacing of 7x4 m. For readings of stomatal condutance and transpiration was used a steady-state null-balcance porometer. For leaf temperature was used a infrared thermometer (Scantenp). To determine the potential of water on the sheet was used a Board of Scholander (Model 3005 - Soil Mosture Equipament Co., Santa Barbara, CA), and to determine the level of chlorophyll was used a clorofiLOG (Falker). The evaluate of quality of fruits was made following the methodology proposed by Bleinroth et al. (1976). The different percentages of wetted area were given by different numbers and types of drip, so as to always apply the same depth of irrigation. The results showed that there was no significant difference among treatments for gs, T, and Tf, but Tf was always higher than the air temperature and can be an indicator of water stress. As the water potential of the leaves, the non-irrigated treatment had lower values in relation to treatment of larger irrigated área. The nonirrigated treatment had lower levels of chlorophyll, especially the content of chlorophyll b, in the south side (more shaded). The production and quality of fruit showed no significant differences.

Processos fisiológicos que modulam a aclimatação fotossintética e o crescimento de plantas ao aumento da concentração de CO2 atmosférico são desconhecidos para a maioria das espécies da região amazônica. Neste sentido, este estudo buscou compreender o comportamento fotossintético e a alocação de carbono em Senna reticulata. Esta espécie ocorre em regiões amazônicas que passam por períodos de seca e alagamento e como estratégia de estabelecimento possui crescimento rápido e alta capacidade fotossintética. O objetivo deste estudo foi comparar os parâmetros de trocas gasosas e de crescimento de plantas cultivadas em câmaras de topo aberto sob diferentes concentrações de CO2 (380ppm-ambiente e 760ppm-elevado). Foram realizadas 6 coletas a cada 15 dias, nas quais foram mensurados pontos relativos as curvas AxPAR e AxCi, calculando-se os parâmetros fotossintéticos de cada curva. Os parâmetros de crescimento foram medidos em coletas destrutivas (biomassa) e não destrutivas (área foliar, altura e nº de folhas). As plantas do tratamento elevado apresentaram maior assimilação fotossintética aos 30 e 45 dias de experimento. Após este período foi observada uma mudança no padrão de alocação (de folha para raízes) e as plantas do elevado apresentaram aclimatação na fotossíntese. A aclimatação foi caracterizada primeiramente por uma redução na velocidade de carboxilação da Rubisco, que foi concomitante com a redução na concentração de N e C foliar. A partir disso ocorreu aumento na senescência das folhas, redução na área foliar e redução na concentração de clorofilas. Somente aos 90 dias é que houve um aumento de 30% na biomassa total das plantas submetidas ao tratamento elevado, resultante do aumento de massa principalmente das raízes e folhas. A transpiração e a respiração das plantas do elevado tenderam a ser menores ao longo de todo o tempo, sendo esta diferença significativa apenas aos 75 dias. Apesar das folhas possuírem menor área foliar e número de folhas, foi observado pela análise de massa especifica das folhas que as plantas do tratamento elevado possuem maior massa em relação às do ambiente, possivelmente pelo maior acúmulo de amido. A eficiência no uso da água foi maior nas plantas do elevado aos 30, 75 e 90 dias. A partir desses dados é possível concluir que S. reticulata submetida ao dobro da concentração atual de CO2, desenvolve processos de aclimatação fotossintética sob longa exposição ao elevado CO2, porém consegue produzir mais biomassa. / Physiological processes that modulate growth and photosynthetic acclimation of plants to increased atmospheric CO2 concentration are unknown for most species in the Amazon region. This study aimed to understand the photosynthesis and carbon allocation in Senna reticulata. This species occurs in the Amazonian regions that experience periods of drought and flooding and it has a fast growth and a high photosynthetic capacity as a strategy for its establishment. S. reticulata plants were grown in open top chambers under different concentrations of CO2 (380ppm Ambient - 760ppm Elevated) and their gas exchange and growth were compared. The harvests were performed at 15, 30, 45, 60, 75 and 90 days of experiment. At each date, AxPAR and AxCi curves were carried out to calculate the photosynthetic parameters. Growth parameters included biomass, leaf area, height and number of leaves. The plants of elevated CO2 presented higher photosynthetic assimilation at 30 and 45 days of experiment. After this period was observed a change in the carbon allocation (e.g. root to leaf) and the plants at elevated CO2 demonstrated a photosynthetic acclimation. This acclimation was characterized primarily by a reduction in velocity of carboxylation of Rubisco, which was concomitant with the reduction in N and C concentration in leaves. Also, the plants at elevated CO2 showed an increase in leaf senescence and a reduction in leaf area and chlorophyll concentration. After 90 days there was an increase (i.e. 30%) in total biomass of plants growing under elevated CO2, due to increase of roots and leaves biomass. The transpiration and respiration rates of plants at elevated CO2 tended to be lower throughout the experiment and the significant difference was found at 75 days. Although the leaves have less leaf area and leaf number, it was observed that specific leaf area from elevated CO2 treatment showed higher biomass when compared to ambient CO2. That difference possibly occurred due to greater starch accumulation. The water use efficiency was greater in plants from the elevated CO2 at 30, 75 and 90 days. From these data we conclude that S. reticulata grown at the elevated CO2 produces more biomass despite occurs the photosynthetic acclimation under long exposure to high CO2.

Master of Science / Department of Biology / Jesse B. Nippert / The impacts of climate change over the next 100 years on North American grasslands are unknown. Climate change is projected to increase rainfall and seasonal temperature variability, leading to increased frequency of drought and decreased rainfall amounts for many grassland locations in the central Great Plains of North America. To increase our ability to predict the effects of a changing climate, I measured multiple morphological and physiological responses from a diverse suite of C3 and C4 grasses. Due to varying characteristics associated with the different photosynthetic pathways, these grass species respond differently to altered temperature and precipitation. I monitored grass physiology and microanatomy in conjunction with varying watered availability to replicate drought. In the second chapter, I observed leaf-level physiology and root level morphology of C3 and C4 grasses when exposed to 100% water reduction. Results indicated that response to water reduction are not always dependent on the photosynthetic pathway. Root-level morphological measurements were found to vary significantly between species in the same genus; F. ovina had the highest specific root length (SRL), which is an indicator of tolerance to environmental variability. Results also indicated that grasses of interest have thresholds that when passed result in a photosynthetically inactive plant; however it was shown that they are able to recover to near pre-drought gas exchange rates when water is re-applied. The third chapter investigated both leaf-level physiology and morphology in dominant C4¬ grasses across Kansas’ rainfall gradient over the growing season. I hypothesized that variation within a species’ physiology would be greater than its’ morphology. I also hypothesized that morphology would predict variability in a species physiological response to changes in climate. This research discovered within a location and species, leaf morphology is fixed across the growing season. Strong correlations between leaf physiology and morphology were observed, however, the strength and relationship changed among the species compared. A. gerardii and P. virgatum exhibited opposing relationships when comparing their photosynthetic rates to the amount of bundle sheath cells. This result highlights strong species-specific relationship between physiology and morphology. My results illustrate the importance of utilizing plant physiology and morphology to understand how grasses may respond to future climate change scenarios.

Abstract This study investigated the ecophysiology of one of the world's northernmost Atlantic salmon (Salmo salar L.) stocks in the River Teno. The juvenile years of salmon of same genetic background were studied in the wild and in the hatchery conditions. In addition, the maternal size effect on reproduction was studied in wild females. Benefit of body size was not only quantitative but also qualitative in reproduction success of the wild female salmon in the River Teno. Total number of eggs and energy content of eggs were higher in big females than in smaller ones. In the hatchery, under natural day length and water temperature conditions, the growth rate, liver glycogen content and condition factor of the parr was higher than in the wild. The liver glycogen content of the hatchery-reared parr increased throughout the growing season and decreased during winter, whereas that of the wild parr was the lowest in summer, and stayed relative stable from September to May. The observed differences in annual fluctuation in liver glycogen content may reflect the differences in carbohydrate content of feed and in behaviour between the hatchery and wild. Overall, the hatchery-reared juveniles maturated and smoltificated 1–2 years earlier than the wild fish. The mean age of wild precocious males was 3 years and that of wild smolts 4 years. However, there was considerable variation in the age of precocious males (1–6 yr) and smolts (2–8 yr) in the wild. The maturing and smolting juvenile age groups were restricted to two (1–2 yr and 2–3 yr, respectively) in the hatchery. In June, the hypo-osmoregulatory ability of hatchery smolts was developed parallel to the wild smolts. Some differences in physiological parameters between different smolt groups could be observed in the wild and between hatchery-reared and wild smolts indicating that completing of smolting process varies to some extent under different conditions. However, the hatchery-reared smolts showed higher levels of fin damage and body energy stores than the wild smolts. As the hatchery practices should aim at controlling the quantity and quality of the juvenile salmon in production, the environmental conditions governing the physiological development of the juvenile fish should be taken into account. Hatchery practices should be planned so that the seasonal timing of smolting would follow the wild fish as close as possible.

South American genus Lasiocephalus colonized high altitudes of the tropical Andes, the so called páramo, from lower elevations of the Andean forest. Páramo is a specific high-altitude environment characterised by pronounced diurnal changes in temperature, growing season over the entire year, low average temperatures, generally high humidity, and intense solar radiation. These specific environmental conditions are reflected by anatomical characters of the species. Given the known phylogeny of the group it was possible to observe anatomical adaptations along steep gradient of environmental conditions from forest to páramo. The hypothesis about adaptive changes that occurred during the colonization of the páramo habitats was confirmed. Observed characteristics were, for example, leaf area and thickness, epidermal cells cuticle and cell wall thickness, epidermal cells lumen height, ratio of palisade and spongy parenchyma, stomatal area, stomata length and width, stomata pore length and sieve elements average area. Results suggest that the anatomy of the plants reflect the environmental conditions of the habitats rather than the species phylogeny.

Eastern hemlock (Tsuga canadensis [L.] Carr.) is a foundation species that occupies a unique niche in forest ecosystems and which often forms pure stands throughout the eastern United States. Throughout the last half of a century, widespread mortality of T. canadensis had been occurring with the introduction of the invasive pest, hemlock woolly adelgid (Adelges tsugae Annand) (HWA). HWA now threatens to destroy millions of hectares of hemlock dominated forests and to disrupt its associated ecosystems. In order to determine how HWA impacts hemlock physiology, three sites with various degrees of infestation were chosen and half of the trees at each site were treated with imidacloprid (Merit® 2 F, Bayer, Kansas City, MO) while the rest were left untreated. Needle gas exchange was assessed monthly using a LI-COR 6400 portable open path gas exchange system (LI-COR Inc, Lincoln NE). Chlorophyll fluorescence and bud break were also characterized for all trees at two of the three sites. After one complete growing season, we found a slight increase in photosynthetic rates (4.98 %), increased bud break at Fishburn (562 %) and Mountain Lake (25.6 %) sites, and no change in chlorophyll fluorescence for imidacloprid treated trees. These results suggest that HWA is causing tree mortality largely through a reduction of leaf area and not a reduction in leaf level photosynthetic capacity. By quantifying the physiological response of T. canadensis to HWA, better insights can be made into understanding tree decline as it relates to HWA. / Master of Science

The study of population biology and genetic diversity provides insights to the potential for colonization and can detect geographic patterns of invasion and range expansion, which is essential to predict how species might react to dynamic environments and the global climate change. An outstanding example for a successful colonizer is the Shepherd’s Purse (Capsella bursa-pastoris (L.) Medik.). It is closely related to Arabidopsis thaliana, the “lab rat“ of plant scientists, and originated 100-300 kya from the hybridization between an ancestral C. orientalis and an ancestor from the C. grandiflora/rubella lineage according to the current literature (Douglas et al., 2015). Many species invasions are the direct or indirect consequence of human activities, and the worldwide distribution of the Shepherd’s Purse is partially associated with prehistorical human migration (e.g. Neuffer & Hurka, 1999; Cornille et al., 2016). With the novel genome-wide restriction site-associated DNA sequencing (RADseq) it is possible to perform population genetic studies of unprecedented depth and complexity and allowed the exploration of evolutionary history, range expansion and invasion patterns of this plant species. I will show here that a large number of loci and a wide global sampling area, using seed collections from nearly all over the world covering a large part of the whole distribution area of this ubiquitous weed, reveal finer-scale population structure of C. bursa-pastoris than has previously been detected. The work proposed here generates a comprehensive picture of phenotypic diversity in relationship to genetic variation within C. bursa-pastoris. Genetic variation is clearly geographically structured and split into two lineages apparently adapted to different environments, with one population predominantly distributed in Mediterranean climate regions and the other predominantly in temperate climate regions. The worldwide distribution patterns of the genetic variation can be explained by intra- and intercontinental migration, but environmental filtering due to climate pre-adaption seems also involved. The two clusters point to an early diversification into two lineages or may even suggest multiple origins of the species.This dissertation consists of three papers and manuscripts written during my time as a doctoral student at the Osnabrück University.