On the following subject: “Trophic ecology of the Ross's seal (Ommatophoca rossii): contribution of bulk isotopy and amino acids”
Thursday 5 March 2026 at 1pm in the Alboran Room, and will remain available to discuss his work afterwards until 3pm.
The seminar zoom link is:
https://univ-amu-fr.zoom.us/j/97238493180?pwd=XWoysmrz1tASbI6AYeJtQvgUYz5ctS.1
Because they tend to spend most of the year at sea, Ross's seals (Ommatophoca rossii) is one of the least studied marine mammal species in the Southern Ocean. Direct physical encounters, which are necessary for instrumentation and biological sampling, are therefore limited to the short moulting period or the weaning of newborn pups when they are on the pack ice. As a result, fundamental aspects of the biology of the Ross seal, such as its trophic ecology, remain poorly understood. The measurement of global carbon isotope values (δ¹³Cbulk) and nitrogen (δ¹⁵Nbulk) of blood, fur, epidermis and vibrissae from 48 seals sampled in the Indian sector of the Southern Ocean, carried out as part of this study, provides valuable information on this subject. Statistical analyses revealed no disparities between males and females, but a significant difference in bulk isotope values between tissues, raising questions about the trophic ecology of Ross's seals throughout the year.
However, nitrogen bulk isotope data has one major limitation: it reflects both the trophic information of predators and the values at the base of food webs, the values of which are seasonally variable and often difficult to estimate. Superimposing these two signals reveals the inherent limitations of this method, particularly for highly mobile predators. To remove the uncertainties surrounding the origin of variations in δ15Nbulk, the measurement of δ15N of amino acids plays a key role in distinguishing the contribution of environmental factors from that of trophic changes.