Parmi les genres responsables des efflorescences algales nuisibles, le genre Alexandrium est certainement l'un des plus importants en termes de diversité, de distribution et d'importance d'impacts. Lors de cette thèse nous avons essayé de comprendre les causes d'introduction et les facteurs favorisant l'établissement et la récurrence des blooms d'Alexandrium catenella/tamarense à travers la comparaison des efflorescences de ce complexe sur deux sites contrastés au niveau trophique : la lagune de Thau en France et la baie d'Annaba en Algérie. Afin de mieux comprendre les déterminismes environnementaux favorisant ce phénomène, une étude comparative a été réalisée à partir des données recueillies sur le terrain durant un suivi bi mensuel in situ au cours de l'année 2010-2011 et sur les données disponibles dans la littérature. La comparaison des paramètres physicochimiques entre les deux sites d'études indique que sur une période de 18 ans, le changement commun majeur qui coïncide avec l'apparition d'Alexandrium catenella est la forte diminution des concentrations en phosphore réactif dissous, ce qui peut induire une limitation de croissance des autres organismes et favoriser ainsi le développement de cette espèces. Au cours de ce travail nous avons développé un protocole d'établissement de cultures monoclonales à partir du sédiment, grâce auquel nous avons obtenu pour la première fois une trentaine de souches d'Alexandrium de la baie d'Annaba. Les analyses morphologiques et le ribotypage effectués sur ces souches ont révélé qu'il s'agit d'Alexandrium catenella du groupe IV (clade Asie tempéré). L'analyse toxinique a révélé que les concentrations et la composition en toxine de ces souches sont assez proches de celle d'A. catenella de Thau. Lors de cette thèse nous nous sommes également intéressé au rôle que peut jouer la diversité intraspécifique dans la dynamique des efflorescences au sein du complexe d'Alexandrium catenella/tamarense. Des comparaisons des taux de croissance, de phases de latence, des capacités de croissance sur différents milieux de culture sur plusieurs souches d'Alexandrium tamarense de Thau ont révélé une grande diversité intraspécifique des paramètres testés. Le profile toxinique et la croissance de nombreuses souches d'Alexandrium catenella de la baie d'Annaba ont révélé également une variabilité considérable. Les résultats de notre étude laissent supposer que la diversité intraspécifique joue un rôle fondamental avec certaines conditions environnementales dans la survie aux pressions de sélections et assurent la pérennité des blooms d'Alexandrium et leur propagation dans différents écosystèmes. / Among the genera responsible for harmful algal blooms, the genus Alexandrium is certainly one of the most important in terms of diversity, distribution and significance of impacts. In this thesis we tried to understand the introduction and factors favoring the establishment and recurrence of Alexandrium catenella / tamarense blooms by comparing these events in two contrasting trophic sites: Thau lagoon in France and the Bay of Annaba in Algeria. To better understand the environmental determinism promoting this phenomenon, a comparative study was conducted using data collected in the field during a monthly parallel monitoring during the 2010-2011 year and the data available in the literature. Comparison of physicochemical parameters between the two study sites indicates that over a period of 18 years, the major common change that coincides with the appearance of Alexandrium catenella is the sharp decrease in concentrations of dissolved reactive phosphorus, which can limit growth of other organisms and thus promote the development of this species. In this work we developed a protocol for the establishment of monoclonal cultures from sediments by which we got for the first time thirty Alexandrium strains from Annaba bay. Morphological analysis and ribotyping performed on these strains showed that it is Alexandrium catenella group IV (temperate Asia clade). The analysis revealed that toxin concentrations and toxin composition of these strains are quite similar to that of A. catenella from Thau. In this thesis we also looked at the role that intraspecific diversity can play in the dynamics of blooms within the complex Alexandrium catenella / tamarense. Comparisons of growth rates, lag phases, capacity for growth on different culture media investigated among several strains of Alexandrium tamarense of Thau, revealed a high intraspecific diversity of parameters tested. The toxin profile and the growth of many strains of Alexandrium catenella from Annaba bay also showed considerable variability. The results of our study suggest that intraspecific diversity plays a key role along with certain environmental conditions for the survival against selection pressures and allows the sustainability of Alexandrium blooms and their propagation within different ecosystems.

O milho geneticamente modificado MON810, que expressa a proteína Cry1Ab de Bacillus thuringiensis Berliner, está em fase de avaliação e aprovação para liberação comercial no Brasil. Sendo assim, o objetivo da presente pesquisa foi o de estudar os efeitos de MON810 sobre a entomofauna em Barretos/SP e Ponta Grossa/PR no período de 1999 a 2001. O levantamento de insetos foi realizado por meio de diferentes armadilhas (alçapão, bandeja d'água, cartão adesivo e rede de varredura) e contagem de insetos nas plantas de milho, visando avaliar o efeito do milho MON810 sobre a comunidade de insetos, guildas tróficas e dinâmica populacional das espécies predominantes, incluindo organismos benéficos e pragas não-alvo. A interação tritrófica envolvendo milho MON810, Spodoptera frugiperda (J.E. Smith) e Doru luteipes (Scudder) também foi avaliada no presente trabalho. Adicionalmente, um estudo comparativo da comunidade geral de insetos nas diferentes safras de milho foi realizado com o uso de armadilha luminosa. Os tratamentos avaliados foram o milho geneticamente modificado MON810 (MON), milho convencional com aplicação de inseticidas (CCI) e milho convencional sem aplicação de inseticida (CSI). Foi coletado um total de 957.081 espécimes e 409 diferentes espécies. Baseado na análise faunística e índices de riqueza, diversidade, eqüitabilidade e similaridade, não foram observadas diferenças entre os tratamentos na comunidade de insetos. Estes resultados foram também confirmados com as análises de componentes principais e de Kruskal-Wallis. Não foram observadas diferenças significativas entre os tratamentos quanto à proporção relativa de diferentes guildas tróficas analisadas (predadores, parasitóides, polinizadores, decompositores, sugadores e mastigadores). Também não foi observado efeito do milho MON810 na dinâmica populacional das espécies predominantes de aranhas e insetos de diferentes guildas tróficas, incluindo pragas não-alvo e insetos benéficos (Carabidae, Coccinellidae, Chrysopidae, Hemerobiidae, Syrphidae, Tachinidae e Apidae). Avaliações de S. frugiperda e D. luteipes nas plantas de milho confirmaram a eficiência de MON810 no controle desta praga e a sua não interferência na dinâmica populacional do predador. E finalmente, diferenças significativas foram observadas na comunidade geral de insetos nas diferentes safras avaliadas. Portanto, nenhum efeito do milho MON810 foi detectado no presente estudo sobre a comunidade de insetos. / The genetically modified corn MON810, which expresses the Cry1Ab protein from Bacillus thuringiensis Berliner, is under evaluation and approval for commercial release in Brazil. Therefore, the objective of this research was to study the effect of MON810 on insect community in Barretos/SP and Ponta Grossa/PR from 1999 to 2001. The evaluations were based on insect sampling with the use of different traps (pitfall, color tray, sticky trap and sweep net) and insect counts on corn plants to evaluate the effect of MON810 on insect community, throphic guilds and population dynamics of predominant species, including beneficial organisms and non-target pests. Tritrophic interaction involving the corn MON810, Spodoptera frugiperda (J.E. Smith) and Doru luteipes (Scudder) was also evaluated in this study. Additionally, a comparative study of general insect community in different corn growing seasons was conducted with the use of a light trap. The following treatments were evaluated: genetically modified corn MON810 (MON), conventional corn with insecticide application (CWI) and conventional corn without insecticide application (CWI). A total of 957,081 specimens were collected, distributed among 409 different species. Based on faunistic analysis and indexes of richness, diversity, evenness and similarity, there were no differences in the insect community among treatments. These results were also confirmed by principal component and Kruskal-Wallis analysis. No statistical differences were found among treatments in the relative proportion of different trophic guilds evaluated (predators, parasitoids, pollinators, decomposers, suckers and chewers). There was also no effect of MON810 on population dynamics of predominant species of spiders and insects of different trophic guilds, including non-target pests and beneficial insects (Carabidae, Coccinellidae, Chrysopidae, Hemerobiidae, Syrphidae, Tachinidae and Apidae). Evaluations of S. frugiperda and D. luteipes on corn plants confirmed the efficacy of MON810 in the control of this pest and its no effect on the population dynamics of D. luteipes. And finally, significant differences were found in the general insect community in different corn growing seasons. Therefore, no effect of the corn MON810 was detected in this study on insect community.

Atmospheric nutrient loading and transport though precipitation and dry deposition is one of the least understood yet one of the most important pathways of nutrient transport into many lakes. These nutrients, phosphorus and nitrogen, are essential for aquatic life and often play major roles in algae blooms that occur in lakes and reservoirs. Often heavy algal growth intensifies a variety of water quality problems. Utah Lake may be even more susceptible to atmospheric deposition due to its large surface area to volume ratio and proximity to Great Basin dust sources. In this study, eight months of atmospheric deposition data were collected and analyzed from five locations near Utah Lake. Geospatial maps were created to show the temporal distribution of phosphorus and nitrogen. Evaluation of the atmospheric deposition results indicate that between 8 to 350 tons of total phosphorus and 46 to 460 tons of dissolved inorganic nitrogen were deposited onto the surface of Utah Lake over an eight-month period. Both estimates were based on assuming that the deposition decreased exponentially from the sampling station to the middle of the lake. The large difference results from using only samples with no visible particles or insects present to give the low estimate and all samples to give the high estimate. These nutrient loading values are very significant in that it has been estimated that only about 17 tons year-1 of phosphorus and about 200 tons year-1 of nitrogen are needed to support a eutrophic level of algal growth in Utah Lake. Atmospheric deposition was found to be a major contributor in providing a eutrophic nutrient load to Utah Lake. Further, it is likely that the actual deposition loading is much higher than 8 tons per 8 months thus indicating that deposition alone adds a eutrophic phosphorus loading to the lake. Since conditions are similar in much of the Great Basin and other areas of Western United States, this seems to be a very significant finding relative to nutrient evaluation and feasible management scenarios. The results also indicate that one might expect to see more cyanobacteria blooms (Harmful Algal Blooms) in shallow ponds in this area if atmospheric deposition is the main source of nutrients, since N to P ratios are low and thus more situations arise where a shortage of ionic nitrogen favors these nitrogen-fixing cyanobacteria.

The degradation of the environment and climate change represent some of the most important environmental issues affecting our society today, and we need to better understand what can be done in order to mitigate the negative effects of human activity on the environment. The present program of research proposes to examine, through three studies, how the frequency of pro-environmental behaviours (PEB) and harmful-environmental behaviours (HEB) are related to self-determined (SDM) and non-self-determined motivation (NSDM), stages of change (SOC), the satisfaction versus the frustration of basic psychological needs as defined by Self-Determination Theory, and nature relatedness. In Study 1 (N = 377), a scale was created to measure two distinct types of environmental behaviours, PEB and HEB, and the relationships between these types of environmental behaviours and SDM and NSDM were examined. Results demonstrated that both types of behaviours loaded on two distinct factors when conducting an exploratory factor analysis, that they were associated differently with environmental motivation, and that levels of motivation were different according to the reported frequency of adoption of PEB and HEB. In Study 2a (N = 266) and 2b (N = 529), the role of stages of change (SOC) was introduced to determine whether environmental motivation and behaviours were different across SOC and to examine whether SOC played a mediating or moderating role in the relationship between environmental motivation and behaviours. Results indicated that people in the later SOC displayed higher levels of SDM and PEB while people in the earlier stages reported higher levels of NSDM and HEB. It was also observed that SOC partially mediated the relationship between environmental motivation and behaviours. In Study 3 (N = 507) nature relatedness was compared to the satisfaction and frustration of basic psychological needs proposed by SDT to examine their respective roles in the association of motivation, SOC, PEB and HEB. Results revealed that nature relatedness was incremental to need satisfaction and frustration with regard to levels of SDM. Also, nature relatedness was an important determinant of SOC and both types of environmental behaviours. As for the proposed model, it was demonstrated that high levels of nature relatedness were associated with higher PEB and lower HEB through partial mediation by SDM and SOC, while need frustration was linked to a higher reported frequency of HEB through mediation by NSDM. Overall this thesis expands on SDT research by highlighting the importance of including HEB in conjunction with PEB and by demonstrating the prominent roles that SOC and nature relatedness could play in the motivational process associated with environmental action.

Karenia brevis is a toxic marine dinoflagellate species that blooms almost every year in the Gulf of Mexico. These blooms have had devastating effects on local economies, as well as on the fauna of the area. The ECOHAB:Florida project was founded to study the population dynamics and trophic impacts of K. brevis. The project included a series of monthly hydrographic offshore research cruises, as well as monthly surveys of a transect along the 10-meter isobath of the West Florida Shelf. This study focused on data from the alongshore transect over a three-year period (1999-2001). Physical parameters (temperature, salinity, and density) and chemical parameters (particulate carbon, nitrogen, and phosphorus; dissolved inorganic nitrogen and phosphorus) of the West Florida Shelf were analyzed. The amount of chlorophll a and the location and amount of K. brevis cells present were also examined. Clear spatial, seasonal, and interannual patterns in the hydrographic parameters, particulate matter (C, N, P), dissolved inorganic nutrient (nitrite, nitrate, and phosphate), and chlorophyll a concentrations were found. At various times throughout the study, the location of K. brevis blooms was influenced by all of these factors except for the amount of dissolved inorganic nutrients. There were differences in particulate matter ratios present in bloom and non-bloom periods. No clear-cut differences in dissolved inorganic nutrients between bloom and non-bloom periods were found. Finally, relationships between the biological indicators of blooms (i.e., chlorophyll a) and the aforementioned physical and chemical parameters were found.

Optical research has shown that Karenia brevis has distinct spectral characteristics, yet most studies have focused exclusively on absorption and chemical properties, ignoring the size, shape, internal structure, and orientation, and their effect on scattering properties. The application of a new spectral interpretation model to K. brevis is shown to provide characterization of unique spectral information, not previously reported, through the use of scattering and absorption properties. The spectroscopy models are based on light scattering and absorption theories, and the approximation of the frequency-dependent optical properties of the basic constituents of living organisms. The model uses the process of mathematically separating the cell into four components, while combining their respective scattering and absorption properties, and appropriately weighted physical and chemical characteristics. The parameters for the model are based upon both reported literature values, and experimental values obtained from laboratory grown cultures and pigment standards. Measured and mathematically derived spectra are compared to determine the adequacy of the model, contribute new spectral information, and to establish the proposed spectral interpretation approach as a new detection method for K. brevis. Absorption and scattering properties of K. brevis, such as cell size/shape, internal structure, and chemical composition, are shown to predict the spectral features observed in the measured spectra. This research documents for the first time the exploitation of every spectral feature produced by the interaction of light with the cellular components and their contribution to the total spectrum of a larger (20-40 µm) photosynthetic eukaryote, K. brevis. Overall, this approach could eventually address the detection deficiencies of current optical detection applications and facilitate the understanding of K. brevis bloom ecology.

Harmful algal blooms (HABs, or "red tides") of the brevetoxin-producing dinoflagellate Karenia brevis occur periodically along Florida's Gulf coast. Mass mortalities of marine birds have long been associated with these blooms, yet there are few data documenting the accumulation of brevetoxins (PbTx) in the tissues of birds. Post-mortem evaluations were performed on 185 birds representing 22 species collected from October 2001 through May 2006 during red tide and non-red tide events to quantify their body burdens of brevetoxins. A variety of tissues and organs were selected for brevetoxin analysis including blood, brain, heart, fat, stomach or gut contents, intestinal contents or digestive tract, muscle, lung, liver or viscera, kidney, gonads, gallbladder and spleen. Brevetoxin levels in avian tissues ranged from K. brevis which may amass in various tissues of the body. As a consequence, the birds may exhibit acute brevetoxicosis during red tide events or show chronic accumulation effects during non-red tide events.

As human populations increase along coastal watersheds, the understanding and monitoring of Harmful Algal Blooms (or red tides) is an increasingly important issue. A consistent method for accurately detecting red tides using satellite measurements would bring tremendous societal benefits to resource managers, the scientific community and to the public as well. In the West Florida Shelf, blooms of the toxic dinoflagelate Karenia brevis are responsible for massive red tides causing fish kills, massive die-offs of marine mammals, shellfish poisoning, and acute respiratory irritation in humans. In this work, for the first time a long-term dataset (2002~2006) the MODerate Resolution Imaging Spectroradiometer (MODIS) is compared (i.e., matched-up) to an extensive data set of in situ cell counts of K. brevis; provided by the Florida Fish and Wildlife Conservation Commission's Fish and Wildlife Research Institute. The pairing of remote sensing data with near-coincident field measurements of cell abundance was successfully used to derive the basis for the development of an alternative ocean color based algorithm for detecting the optical signatures associated with blooms of K. brevis in waters of the West coast of Florida. Conclusions are geographically limited to the Central West Florida Shelf during the boreal Summer-Fall (i.e., the K. brevis blooming season). The new simpler Empirical approach is compared with other two more complicated published techniques. Their potential is verified and uncertainties involved in the identification of blooms of K. brevis are presented. The results shown here indicate that the operational NOAA method for detecting red tides in the Gulf of Mexico (Stumpf et al., 2003; Tomlinson et al., 2004) performs less accurately than the other two algorithms at identifying K. brevis blooms. The sensitivity and specificity of the Bio-optical (Cannizzaro, 2004; Cannizzaro et al., 2008) and Empirical algorithms are simultaneously maximized with an optimization procedure. The combined use of these two optimized algorithms in sequence provides another new monitoring tool with improved accuracy at detecting K. brevis of blooms. The ability of this Hybrid scheme ranges about 80% for both sensitivity and specificity; and the capability at predicting a correct red tides is 70%, and ~85% for non-blooms conditions. The spatial and temporal knowledge of K. brevis blooms can improve the direction of field monitoring to areas that should receive special attention, allowing better understanding of the red tide phenomenon by the scientific community. The relevant agencies can also develop more appropriate mitigation action plans, and public health guidance can be improved with the enhancement of sustainable costal management strategies.

The Laurentian Great Lake, Lake Erie is an invaluable global resource and its watershed is home to over 11 million people. The pressures placed on the lake because of this high population caused Lake Erie to experience numerous environmental problems, including seasonal hypoxia and harmful algal blooms. While these topics have been widely studied in Lake Erie for over 40 years a more nuanced understanding of the interaction between phytoplankton and nutrient is needed to properly address the problems continuing to face the lake. In this study we combine classical limnological and cell growth experiments with modern molecular biological techniques and microscopy to more completely describe the aquatic microbial ecology of the lake. We used an oxalate rinse technique to examine the surface absorbed P pool of the toxic cyanobacterium Microcystis aeruginosa grown under a range of P conditions, as well as the general Lake Erie plankton assemblage. Our results suggest that while Microcystis is plastic in its cellular P needs, the ratio of intracellular to extracellular P remains stable across growth conditions. We describe the effect of the phosphonate herbicide glyphosate on the Lake Erie phytoplankton community using laboratory cell growth studies, field microcosm experiments and PCR amplification of a gene implicated in the breakdown of this compound from the environment. Results from these experiments suggest that the presence of glyphosate can affect community structure in multiple ways and may explain areas of unexplained phytoplankton diversity in coastal areas of Lake Erie. We also show heterotrophic bacteria are likely critical to the breakdown of glyphosate and further illustrate that understanding the context of the larger microbial community is critical to understanding the ecology of the constituent members of the community. Finally, we investigate the activity of the phytoplankton community in winter months with a focus on diatoms abundant in Lake Erie under the ice. We show these diatoms are active and that the winter bloom is a likely source of carbon important to seasonal hypoxia formation. Together, these studies significantly enrich our understanding of how phytoplankton influence important ecological processes in Lake Erie.

Virginity Testing, a traditional Zulu pre-nuptial custom that determines the worth of a bride, has been resurrected in communities in KwaZulu-Natal in South Africa as a response to the HIV/AIDS epidemic. The practice takes place during large community festivals when young girls have their genitals physically examined to determine whether they are virgins and results are made public. Supporters of the tradition claim that in fostering a value of chastity among its youth, it encourages abstinence from sexual intercourse which leads to a lower HIV infection rate and prevents the disease from spreading. Human rights activists disagree; Rather than slowing the spread of a disease, they argue, the practice instead endangers girls. Those who fail are often shunned and turn to prostitution, while those who pass may be exposed as potential targets for rape (due to a myth that says intercourse with a virgin cures HIV/AIDS). Despite a ban on the practice in 2005, the testing festivals continue, and are described by supporters as an important part of the preservation of Zulu culture. This thesis examines the ways in which human rights may be re-negotiated for young girls in Zulu communities while maintaining a respect for local culture. It moves beyond the traditional debate between relativism and universalism in order to propose solutions to rights violations in culturally diverse contexts by exploring ideas of inclusive human rights and capabilities theories.