Abstract: Identifying drivers of population trends in migratory species is difficult, as they can face many stressors while moving through different areas and environments during the annual cycle. To understand the potential of migrants to adjust to perturbations, it is critical to study the connection of different areas used by different populations during the annual cycle (i.e. migratory connectivity). Using a large-scale tracking data set of 662 individual seabirds from 2 sympatric auk meta-populations (common guillemots Uria aalge and Brünnich’s guillemots U. lomvia) breeding in 12 colonies throughout the Northeast Atlantic, we estimated migratory connectivity in seasonal space use as well as occupied environmental niches. We found strong migratory connectivity, within and between species. This was apparent through a combination of seasonal space use and occupied environmental niches. Brünnich’s guillemot populations grouped into 2 and common guillemot populations into 5 previously undescribed spatiotemporal clusters. Common guillemot populations clustered in accordance with the variable population trends exhibited by the species, while Brünnich’s guillemot populations are declining everywhere where known within the study area. Individuals from different breeding populations in both species were clustered in their space and environmental use, utilising only a fraction of the potential species-wide range. Further, space use varied among seasons, emphasising the variable constraints faced by both species during the different stages of their annual cycle. Our study highlights that considering spatiotemporal dynamics, not only in space but also in occupied environmental niches, improves our understanding of migratory connectivity and thus population vulnerability in the context of global change.

Abstract: The surface mass balance (SMB) is very low over the vast East Antarctic Plateau, for example in the Vostok region, where the mean SMB is on the order of 20–35 kg m-2 a-1. The observation and modeling of spatio-temporal SMB variations are equally challenging in this environment. Stake measurements carried out in the Vostok region provide SMB observations over half a century (1970–2019). This unique data set is compared with SMB estimations of the regional climate models RACMO2.3p2 (RACMO) and MAR3.11 (MAR). We focus on the SMB variations over time scales from months to decades. The comparison requires a rigorous assessment of the uncertainty in the stake observations and the spatial scale dependence of the temporal SMB variations. Our results show that RACMO estimates of annual and multi-year SMB agree well with the observations. The regression slope between modelled and observed temporal variations is close to 1.0 for this model. SMB simulations by MAR are affected by a positive bias which amounts to 6 kg m-2 a-1 at Vostok station and 2 kg m-2 a-1 along two stake profiles between Lake Vostok and Ridge B. None of the models is capable to reproduce the seasonal distributions of SMB and precipitation. Model SMB estimates are used in assessing the ice-mass balance and sea-level contribution of the Antarctic Ice Sheet by the input-output method. Our results provide insights into the uncertainty contribution of the SMB models to such assessments.

Abstract: This Book Brings Together Expert Opinions From Scientists To Consider The Evidence For Climate Change And Its Impacts On Ticks And Tick-borne Infections, And Provide Predictions For The Future. It Considers What Is Meant By 'Climate Change', How Good Are Climate Models Relevant To Ecosystems, And Predictions For Changes In Climate At Global, Regional, And Local Scales Relevant For Ticks And Tick-borne Infections. It Examines Changes To Tick Distribution And The Evidence That Climate Change Is Responsible. The Effect Of Climate On The Physiology And Metabolism Of Ticks, Including Potentially Critical Impacts On The Tick Microbiome Is Stressed. Given That The Notoriety Of Ticks Derives From Pathogens They Transmit, Do Changes In Climate Affect Vector Capacity? Ticks Transmit A Remarkable Range Of Micro- And Macro-parasites Many Of Which Are Pathogens Of Humans And Domesticated Animals. The Intimacy Between Tick-borne Agent And Tick Vector Means That Any Impacts Of Climate On A Tick Vector Will Impact Tick-borne Pathogens. Most Obviously, Such Impacts Will Be Apparent As Changes In Disease Incidence And Prevalence. The Evidence That Climate Change Is Affecting Diseases Caused By Tick-borne Pathogens Is Considered, Along With The Potential To Make Robust Predictions Of Future Events.

Abstract: In a fast-changing world, polar ecosystems are threatened by climate variability. Understanding the roles of fine-scale processes, and linear and nonlinear effects of climate factors on the demography of polar species is crucial for anticipating the future state of these fragile ecosystems. While the effects of sea ice on polar marine top predators are increasingly being studied, little is known about the impacts of landfast ice (LFI) on this species community. Based on a unique 39-year time series of satellite imagery and in situ meteorological conditions and on the world's longest dataset of emperor penguin (Aptenodytes forsteri) breeding parameters, we studied the effects of fine-scale variability of LFI and weather conditions on this species' reproductive success. We found that longer distances to the LFI edge (i.e. foraging areas) negatively affected the overall breeding success but also the fledging success. Climate window analyses suggested that chick mortality was particularly sensitive to LFI variability between August and November. Snowfall in May also affected hatching success. Given the sensitivity of LFI to storms and changes in wind direction, important future repercussions on the breeding habitat of emperor penguins are to be expected in the context of climate change.

Abstract: Climate And Water Cycle Reconstruction Over The Last Centuries And Prediction Should Be Improved In The Southern Hemisphere (E.g. Last Ipcc Report). First, Direct Observations Are Scarce (E.g. In Antarctica, Mainly Basic Automatic Weather Station – Aws – Only Since The 50’s And Satellite Observations). As A Consequence, Climate And Water Cycle Reconstructions Are Largely Dependent On Proxy Measurements Such As Water Isotopes In Polar Ice Cores, Even Over The Last Century. Second, Climate And Water Cycle Reconstructions Using Models Should Be Improved. In Particular, Problems Have Been Identified For (1) Estimation Of Precipitation Amounts (Large Discrepancies Among Models Over The Austral Ocean And The Ice-sheet), (2) Description Of Particular Atmospheric Processes Associated With Cloud Microphysics And Exchanges Between Surface And Atmosphere In Polar Regions And (3) Seasonal To Interannual Evolution Of The Locations Of The Westerlies And Subtropical Jet And Associated Air Mass Trajectories. The Last Aspect Has Important Direct Consequences For The Atmospheric Dynamics In This Region But Also Indirect Consequences Such As The Links Between Westerlies, Co2 Outgassing And Sea Ice Extent In The Austral Ocean (Saunders Et Al. 2018; Menviel Et Al. 2018; Holland And Kwok, 2012). With The Objectives To Provide (1) A Better Description Of Water Cycle Dynamic In The Southern Ocean At Annual And Interannual Scales And (2) An Improved Transfer Function Between Climate / Water Cycle And Water Isotopes In This Region, A Bunch Of Instruments Measuring Continuously The Isotopic Composition Of Water In The Water Vapor And In The Precipitation Has Been Installed Over The Last Years Along A Transect From La Réunion To Antarctica.first Results From The Antarctic Instruments Reveal Clear Isotopic Signatures Of Large Scale Water Cycle Features Such As Atmospheric Rivers Dominating The Surface Mass Balance In Antarctica. In La Réunion, An Extensive Study Of The Drivers Of The Isotopic Composition Of The Water Vapor Showed That The Influence Of The Subtropical Westerly Jet Dominates The Water Isotopic Signal At Night. To Connect The Two Regions, An Instrument Is Running On Amsterdam Island Since November 2019 With First Results Showing A Clear Isotopic Signature During The High Pressure And Low Pressure Synoptic Events. Still, No In-depth Study Of The Data Trying To Connect The Isotopic Record In Amsterdam Island To Larger Scale Patterns Of The Water Cycle Has Been Initiated.the Goal Of This Internship Is To Provide The First Analyses Of The Isotopic (Water Vapor And Precipitation) Records On Amsterdam Island With A Comparison With Meteorological Data And Environmental Data Collected In Parallel On The Observatory Of Amsterdam Island (E.g. Gaseous Elemental Mercury). After These First Analyses Of The Data, Comparisons Will Be Performed With Water Isotopic Records In La Réunion Over Selected Events (Subtropical Jet Or Cold Fronts Intrusions). This Study Will Involve Analyses Of Meteorological Maps As Well As Backtrajectories.this Internship Requires Skills For (Python Or R Languages) And Involves Large Interactions Within A Large Research Team.