The Arctic is experiencing an acceleration of environmental modifications which could affect Arctic species and the entire marine ecosystems. The ARCTIC-STRESSORS project thus proposes to use a multidisciplinary approach to investigate at the pan-Arctic scale the combined effects of multiple environmental stressors (pollution, sea-ice loss and warming temperatures) on Arctic seabirds. More specifically, this project will aim 1) to investigate the importance of sea ice for Arctic seabirds and how melting sea ice might enhance bird exposure to mercury (Hg), and how these two combined environmental stressors could affect bird behavior and fitness. 2) To study the impacts of Hg on seabird thermoregulatory capacities and how the combined temperature increase, Hg contamination and sea ice retreat will affect bird energetic niches and ultimately their distribution through the Arctic.

DELTA Project Description Project Background Deltas are dynamic systems driven by constantly changing interactions between land-based fluvial and ocean processes. These flat agricultural lands, accounting for less than 1% of Earth’s land, are vital for the food security of more than half a billion of people. The relative sea level rise (RSLR) and extreme sea levels (ESL) combined with a rapidly growing population and an increasing impact of human activities, threaten the delta communities. In this context and despite the importance of the RSLR-ESL interactions in the delta regions, and particularly in the tropical regions, only a handful of studies has been conducted on this subject. The threat of increasing coastal flood risk emerges as a probable consequence of climate change. Yet, to date comprehensive projections of RSLR-ESL, that include mean sea level, vertical land motions, tides, waves, and storm surges do not exist. Problem Statement The classical probabilistic methods, applied, for example, for designing coastal defenses (concepts of return level and return period), assume the stationarity of historic storm statistics, in the sense that their statistical properties do not change with time. However, many studies have shown that the effect of low-frequency climatic variability, climate change and human interventions, cause non-stationarity. If the data have non-stationary variance, there can be more extreme events than predicted by theory based on the stationary assumption. Moreover, coastal inundation results not only from nonlinear interactions of oceanographic processes, but also from hydrological, and meteorological events, and land vertical motions. This “compound” depends upon the nature and number of physical processes, the range of spatial and temporal scales and the strength of dependence between these processes. We must investigate how to represent and model these compound events. To address a complex real-world problems associated with the RSLR-ESL coastal inundations, we need to employ together data and techniques issued from both physical and social sciences, in order to propose an integrative applied research focusing on the social vulnerability induced by the RSLR-ESL events in delta regions. Scientific objectives 1.Adapting the statistical framework of ESL events as a time-varying analysis to the specific case of coastal deltaic inundation. 2.Adapting the innovative statistical framework for predictions of RSLR-ESL events through time-varying and multi-dimensional analysis of coastal deltaic inundation as a compound event. 3.Advancing practical applications of the RSLS-ESL analysis to improve estimates of social vulnerability in deltaic regions. Strategy & Approach •Interdisciplinary team: social and physical sciences. •Training area: Mississippi Delta (US) •Application: Ganges-Brahmaputra (Bangladesh) and Irrawaddy (Myanmar) deltas. •Implementing and comparing statistical (Bayesian Networks) and physics-based models (SCHISM) to determine relationships between driving forces, geological constraints, and coastal responses to make probabilistic predictions of deltaic coastal inundations under the future sea level rise scenarios. •Employing together data and techniques issued from both physical and social sciences, in order to propose an integrative applied research focusing on different aspects of social vulnerability induced by the RSLR-ESL events in delta regions. •Exploiting fully the potential of the Earth Observing data. Expected Project Benefits •Inundation hazard maps will be designed to indicate the probability and uncertainties of flooding over delta space. •Specifying the sites where and how many people are living at risk of the RSLR-ESL inundations along the coast of the Ganges-Brahmaputra and the Irrawaddy deltas. •These flooding scenarios, plausible and scientifically credible under future conditions, would serve as a critical decision-making tool for policy makers.

Cyto-nuclear genetic incompatibilities are a type of intrinsic barrier that has recently gained recognition as an important cause of hybrid breakdown and reproductive isolation. These incompatibilities occur when nuclear and cytoplasmic backgrounds that have not co-evolved are tested in hybrids. Mito-nuclear incompatibilities (MNI) are particularly relevant, as they will affect a fundamental function in animals and plants, the production of ATP. While many advances in the comprehension of these mechanisms have been made based on model species, more work has to be done to understand how MNIs affect natural populations facing changing environments. Marine bivalves are tremendous biological models to study how MNI contribute to building reproductive isolation. Many of these species are characterized by large population sizes, high fecundity and high dispersal abilities, factors that should impede the establishment of local adaptation. Despite these characteristics, strong genetic structuring can be observed at geographical scales that are much finer than the expected scale of larval dispersal. In addition, coastal bivalves were subjected to complex historical population fluctuations and range shifts in response to glacial cycles, leading to secondary contact zones that are conducive to developing MNIs. Some bivalve species show a remarkable exception of the maternal inheritance of mitochondria in metazoans: the doubly uniparental mode of inheritance (DUI). In this system, females transmit a “female” mitochondrion that persists in oocytes and in somatic tissues of both sexes, while males pass on “male” mitochondria that persist in the male germ line. The male and female mitochondrial genomes can be highly divergent, begging the question of how DUI evolves and is maintained. This system offers tremendous potential for MNI to develop in inter-populational hybrids, as a network of cyto-nuclear interactions exist. Despite this potential, little information is available on how it might participate to reproductive isolation. Indeed, in DUI species, mito-genetic incompatibilities could be expressed not only between female mitochondrial and nuclear genes (in somatic tissues and oocytes), but also between the male mitochondrial and nuclear genes in sperm of inter-populational hybrids. The project DRIVE aims at determining whether DUI can play a significant role in maintaining barriers to gene flow among divergent populations by the way of MNIs. To meet this objective, we will use the bivalve Limecola balthica as a model system. We will (1) obtain complete male and female mitogenomes from multiple lineages spanning a secondary contact zone, (2) determine, using RNA-seq, whether nuclear isoforms specific to the male mitogenome background are expressed in sperm, (3) use exon capture to measure levels of population differentiation and linkage disequilibrium across nuclear and mitochondrial genes (both males and females) coding for protein complexes implicated in the production of ATP (i.e. the oxidative phosphorylation chain). DRIVE touches on several key questions in organismal and evolutionary biology, such as how highly dispersive organisms such as marine bivalves can develop and maintain local adaptations at narrow geographical scales. Theory predicts that genetic incompatibilities causing population divergence can be trapped by environmental gradients, complicating tremendously the distinction between intrinsic and extrinsic barriers to gene flow. DRIVE will add a new tool to comprehend how these different forces can participate in population divergence. These questions have bearing for biodiversity research (the Bivalvia is a highly diverse group of over 9000 described species), as population divergence can lead to speciation, but also for aquaculture, as the adaptation of shellfish species to a changing environment is a strong societal and economic concern.

The Arctic is an extremely sensitive region threatened by major and increasing pollution risks. Among them, mercury (Hg), which can have high impacts on organisms and populations, has raised major environmental concerns. These concerns are especially high as Hg levels are substantial and should continue to increase in the Arctic marine environment. Although there has been an international effort led over the last decades to characterize Hg concentrations, temporal trends and toxicological effects, some major gaps remain to fully grasp the threats posed by Hg to the Arctic wildlife as well as the risks associated with increasing levels. Relying on a large scale approach and using seabirds as bioindicators, I propose to provide a comprehensive understanding of the Hg contamination of Arctic marine food-webs. To this end, this project will use a unique international, pan-Arctic sampling network allowing the collaborative collection of tissues on various seabird species all around the Arctic. It will first map the spatial distribution of Hg in food webs around the Arctic and define areas requiring protection. Second, it will help identify and understand the sources and pathways of this Hg contamination, both inside the Arctic (where is Hg the most bioavailable in marine ecosystems and where does it come from?) and from outside the Arctic (how are migratory organisms exposed to Hg once they have left the Arctic?). Finally, this project will provide new knowledge about large-scale impacts of Hg, alone or in combination to environmental conditions, on the ecophysiology, energetics and ultimately distribution of Arctic marine top-predators. By combining inputs from different disciplines (ecotoxicology, environmental and analytical chemistry, biogeography, energetics, ecophysiology) and state-of-the-art methodologies, this project will address international priorities regarding the impacts of global change on Polar Regions and the conservation of the world’s biodiversity.

DELTA Project Description Project Background Deltas are dynamic systems driven by constantly changing interactions between land-based fluvial and ocean processes. These flat agricultural lands, accounting for less than 1% of Earth’s land, are vital for the food security of more than half a billion of people. The relative sea level rise (RSLR) and extreme sea levels (ESL) combined with a rapidly growing population and an increasing impact of human activities, threaten the delta communities. In this context and despite the importance of the RSLR-ESL interactions in the delta regions, and particularly in the tropical regions, only a handful of studies has been conducted on this subject. The threat of increasing coastal flood risk emerges as a probable consequence of climate change. Yet, to date comprehensive projections of RSLR-ESL, that include mean sea level, vertical land motions, tides, waves, and storm surges do not exist. Problem Statement The classical probabilistic methods, applied, for example, for designing coastal defenses (concepts of return level and return period), assume the stationarity of historic storm statistics, in the sense that their statistical properties do not change with time. However, many studies have shown that the effect of low-frequency climatic variability, climate change and human interventions, cause non-stationarity. If the data have non-stationary variance, there can be more extreme events than predicted by theory based on the stationary assumption. Moreover, coastal inundation results not only from nonlinear interactions of oceanographic processes, but also from hydrological, and meteorological events, and land vertical motions. This “compound” depends upon the nature and number of physical processes, the range of spatial and temporal scales and the strength of dependence between these processes. We must investigate how to represent and model these compound events. To address a complex real-world problems associated with the RSLR-ESL coastal inundations, we need to employ together data and techniques issued from both physical and social sciences, in order to propose an integrative applied research focusing on the social vulnerability induced by the RSLR-ESL events in delta regions. Scientific objectives 1.Adapting the statistical framework of ESL events as a time-varying analysis to the specific case of coastal deltaic inundation. 2.Adapting the innovative statistical framework for predictions of RSLR-ESL events through time-varying and multi-dimensional analysis of coastal deltaic inundation as a compound event. 3.Advancing practical applications of the RSLS-ESL analysis to improve estimates of social vulnerability in deltaic regions. Strategy & Approach •Interdisciplinary team: social and physical sciences. •Training area: Mississippi Delta (US) •Application: Ganges-Brahmaputra (Bangladesh) and Irrawaddy (Myanmar) deltas. •Implementing and comparing statistical (Bayesian Networks) and physics-based models (SCHISM) to determine relationships between driving forces, geological constraints, and coastal responses to make probabilistic predictions of deltaic coastal inundations under the future sea level rise scenarios. •Employing together data and techniques issued from both physical and social sciences, in order to propose an integrative applied research focusing on different aspects of social vulnerability induced by the RSLR-ESL events in delta regions. •Exploiting fully the potential of the Earth Observing data. Expected Project Benefits •Inundation hazard maps will be designed to indicate the probability and uncertainties of flooding over delta space. •Specifying the sites where and how many people are living at risk of the RSLR-ESL inundations along the coast of the Ganges-Brahmaputra and the Irrawaddy deltas. •These flooding scenarios, plausible and scientifically credible under future conditions, would serve as a critical decision-making tool for policy makers.