Abstract: Monitoring the evolution of snow on the ground and lake ice—two of the most important components of the changing northern environment—is essential. In this paper, we describe a lightweight, compact and autonomous 24 GHz frequency-modulated continuous-wave (FMCW) radar system for freshwater ice thickness and snow mass (snow water equivalent, SWE) measurements. Although FMCW radars have a long-established history, the novelty of this research lies in that we take advantage the availability of a new generation of low cost and low power requirement units that facilitates the monitoring of snow and ice at remote locations. Test performance (accuracy and limitations) is presented for five different applications, all using an automatic operating mode with improved signal processing: (1) In situ lake ice thickness measurements giving 2 cm accuracy up to ≈1 m ice thickness and a radar resolution of 4 cm; (2) remotely piloted aircraft-based lake ice thickness from low-altitude flight at 5 m; (3) in situ dry SWE measurements based on known snow depth, giving 13% accuracy (RMSE 20%) over boreal forest, subarctic taiga and Arctic tundra, with a measurement capability of up to 3 m in snowpack thickness; (4) continuous monitoring of surface snow density under particular Antarctic conditions; (5) continuous SWE monitoring through the winter with a synchronized and collocated snow depth sensor (ultrasonic or LiDAR sensor), giving 13.5% bias and 25 mm root mean square difference (RMSD) (10%) for dry snow. The need for detection processing for wet snow, which strongly absorbs radar signals, is discussed. An appendix provides 24 GHz simulated effective refractive index and penetration depth as a function of a wide range of density, temperature and wetness for ice and snow.

Abstract: The Transfer Of Antibodies From Mothers To Vertebrate Offspring Has Broad Potential Implications In Evolutionary Ecology, From The Adaptive Value Of Maternal Effects To The Role Of Transgenerational Plasticity In Host-parasite Interactions. Following Our Early Finding That Maternal Antibody Can Persist For A Long Time (Several Weeks) After Hatching In Nestlings Of A Long-lived Seabird, The Cory’s Shearwater, We Have Been Exploring (I) How This Neglected Life History Traits Varies Among Species With Contrasted Nestling Rearing Periods And (Ii) Whether The Long Persistence Of Maternal Antibodies Could Be Used To Protect Nestlings Of Long-lived Threatened Species Exposed To Deadly Infectious Agents. We Have Been Investigating This In The Case Of Albatrosses Recurrently Hit By Epizootics Of Avian Cholera On Amsterdam Island (Southern Indian Ocean). The Results Have Implications For Conservation, But Also Highlight How Research In Ecological Immunology Need To Combine Functional And Evolutionary Approaches While Also Keeping In Mind Ecological And Epidemiological Settings.