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Oxygen concentrations are declining in ocean waters globally. This process of deoxygenation is currently recognized as one of the most important changes occurring in marine environments increasingly affected by human-induced nutrient pollution and global climate change. Rates of deoxygenation are particularly high in shallow estuaries, where conditions of hypoxia (oxygen concentrations < 3 mg L-1) may have large effects on biogeochemical cycles by decreasing oxygen zones in sediments, altering benthic communities, and shifting diagenesis towards more anaerobic pathways. Here, I use three estuaries within Waquoit Bay (Massachusetts, USA) as models to test the impact of hypoxia on fundamental biogeochemical processes, and to evaluate decade-scale trends in oxygen dynamics and hypoxic season phenology. In Chapters 1 and 2, I investigate the effect of water-column hypoxia on ecosystem services provided by the sediments, such as nutrient regeneration, pollutant removal, and regulation of greenhouse gas emissions. In a series of experiments designed to simulate low oxygen conditions I found variable biogeochemical responses to hypoxia, including little to no change in ammonium efflux or reactive nitrogen removal through denitrification. I also found that hypoxia significantly increased sediment phosphate efflux, which lowered water-column nutrient ratios for nitrogen to phosphorus and silicon to phosphorus by 50%. In addition, hypoxia led to approximately a 60% decline in sediment uptake of nitrous oxide, representing a diminished ecosystem service. In Chapter 3, I show that oxygen dynamics and hypoxia are changing over time in Waquoit Bay. Using a 17-year (2002–2018) time series of nearly continuous water quality data I found that despite unchanged total nutrient inputs, summer oxygen concentrations declined (by 0.5–2.1 mg L-1, p

At the center of the question of alterity today lies a debate on the role ethnicity, race, religion, and culture each play in the context of multicultural societies. In France the social contract claims to extend equal rights to all of its citizens by simple virtue of their presence in the collective, yet members of minority populations living in France often do not have access to these rights. Arab Muslim immigrants in particular are treated differently than citizens who represent the white, catholic, bourgeois population whose ancestry is seen as being "rooted" in France. While Arab Muslim immigrants are legally citizens of the French Republic, they are unable to gain sufficient "Frenchness" in order to acquire full cultural citizenship in French society. Although native French citizens present this cultural identity as unchanging, it is ultimately through the debate they hold on what constitutes Frenchness that Frenchness is produced. Through the course of my thesis I address the native French population's perceptions of Arab Muslim members of society through Front National (FN) leader Marine Le Pen's Assises Présidentielles speech, Caroline Fourest's socio-political essay Génie de la laïcité, and the Cité nationale de l'histoire de l'immigration's (CNHI) permanent exhibit Repères in order to examine how Frenchness is produced in relation to Arab Muslim immigrants living in France.

The natural gradient of eutrophic conditions that exists in Waquoit Bay, (Cape Cod, Massachusetts) allowed us to examine how key biogeochemical processes respond to eutrophication over time. Using a space-for-time substitution we measured oxygen (O2), nutrient, and di-nitrogen (N2) gas fluxes from sediments collected at four stations. The objective of this study was to assess how sediment metabolism, nutrient cycling, denitrification and the balance between N and P limitation may change over a trajectory of increasing eutrophication. In addition, for two sites we compared our more recent measurements to those made in the bay nearly 20 years ago (1992-1994). While we did not find a spatial pattern that was linearly linked to nitrogen (N) loading, our results show characteristics of a system in change. Sediment oxygen consumption was measured at 45% of its historic rate and ammonium flux at only 30%. The difference in net denitrification rate was particularly large, as our mean rate (29.9 µmol N2-N m-2 h-1) was considerably lower than the mean historic value (172 µmol N2-N m-2 h-1). This 83% reduction represents the substantial dampening of a key microbial process for the removal of reactive nitrogen from the ecosystem. Additionally, at our most impacted site, North Basin, we measured significant rates of net N fixation, indicating that the sediments are becoming a net source of reactive N. In another important example of change, we observed an anomalous efflux of phosphate (PO4 3-) from the sediments during the summer and high ratios of both oxygen uptake to phosphate release (O2:PO4 3-) and ammonium to phosphate release (NH4+:PO4 3-). This unexpected result suggests that, at least in some times of year, Waquoit Bay may be co-limited by both nitrogen (N) and phosphorus (P). If these observations of N and P co-limitation hold into the future, it will have important consequences for the ecology and management of this coastal system.