PhD “Contamination of Arctic seabirds with mercury: the role played by shrinking sea ice”

Updated: about 1 month ago
Job Type: FullTime
Deadline: 01 Jun 2021

This PhD project (3 years) will start on October 1st 2021 and will be co-supervised by Jérôme Fort (LIENSs, La Rochelle), Guillaume Massé (LOCEAN, Concarneau) et David Amouroux (IPREM, Pau).
The PhD student will be based at the LIENSs (Littoral, Environment and Societies) CNRS Research Unit (La Rochelle, France), with several periods spent at the institutes LOCEAN-CNRS (Concarneau and Paris, France) and IPREM-CNRS (Pau, France). One or two field seasons in East Greenland will also be performed.

Funding: The PhD will be funded by the CNRS, the ANR research project ARCTIC-STRESSORS and IPEV field program ADACLIM. The PhD will also be supported by the ARCTOX initiative.

Context:

The Arctic is experiencing an acceleration of environmental modifications. Among them, the development of human activities is resulting in a large, increasing and long-lasting pollution of the Arctic environments. Indeed, hundreds tons of pollutants emitted at northern mid-latitudes are deposited every year in the Arctic through long-range transport, adding to the rising local pollution linked to unprecedented levels of resource extractive industries and tourism in the Arctic. Another major change is the decrease of sea ice thickness and extent, inexorably shrinking to an Arctic free of ice during summer, affecting primary productivity or fragmenting essential habitats for sympagic species. In addition, melting sea ice could enhance the contamination of marine species and ecosystems by releasing pollutants trapped in the ice, or by affecting the cycle of some pollutants (e.g. changes in ice-associated microbial communities, photochemistry and volatilization…). Further, melting sea ice might modify prey availability for predators and thereby change their exposure to contaminants. In this context, a major objective is to understand the combined impacts of melting sea ice and increasing contamination on the Arctic biota, and more specifically to evaluate the role played by the sea ice melt in the species contamination. Among Arctic species, marine top predators such as seabirds are essential components of their ecosystems but are also particularly vulnerable. Seabirds are indeed among the most exposed and the most sensitive organisms to environmental pollutants which increase in concentrations along the food chains (biomagnification process). Some Arctic seabirds also strongly depend upon sea ice to forage.

This PhD project will aim to tackle these questions. To this end, it will focus on mercury (Hg), a neuro- repro-toxicant which still raises major environmental concerns, and on three seabird species with a large scale distribution over the Arctic: the little auk (Alle alle), the black-legged kittiwake (Rissa tridactyla) and the common eider (Somateria mollissima). More specifically, combining different tools (Hg isotopes, ice biomarkers, spatial ecology), objectives will be to identify and understand the use of sea ice by seabirds, their contamination with Hg and the role of sea ice as an Hg source. Different populations with contrasting distributions, both during the breeding and non-breeding periods, will be targeted.

Objectives:

1) Study the sea ice use by seabirds. The PhD candidate will use ice biomarkers (HBI) to trace the use of ice-associated resources. These biomarkers have been used and validated in polar regions, including in seabirds. Developing a multi-species and large scale approach will allow to further extend our understanding of the importance of sea ice for the avian community in a context of rapid environmental modifications. Analyses will be performed within a collaboration with the research unit LOCEAN (Paris/Concarneau).
2) Study sources of Hg in seabirds at large spatial scale through the use of Hg stable isotopes. Hg isotopes were shown to behave as a multiple tracer and a powerful tool to investigate sources of Hg in the environment, including in the Arctic, from specific emission sources or contaminated environmental compartments. Analyses will be performed at Pau (France) under a collaboration with the research unit IPREM.
3) Combine results obtained over the two first objectives to define a new tracer of sea ice as a source of Hg in Arctic seabirds, in order to investigate whether melting sea ice could affect their contamination.
4) All obtained results on sea ice use and Hg contamination could be combined to already existing data on bird ecophysiology and reproduction in order to study their combined effects.


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