Charlotte Sirot, Postdoctoral research fellow

For more details on my projects or to see more about my research:

From the beginning, I have been interested in the impacts that human activities have on aquatic ecosystems and in particular on fish ecology. With a background of veterinary medicine and marine ecology, my reseach investigates the effects of these disturbances on contrasted ecosystems (from tropical freshwater to subpolar marine ecosystems) and at different ecological levels (from individual to species assemblage).

During my PhD, I investigated the role of life history traits and of their temporal changes to understand fish demographic trajectories. In a first approach, I developed a multivariate index to characterize fish demographic variations accounting for changes in both species abundance and occurrence. Then, I demonstrated that temporal variations of this index can be accurately predicted by fish
life history traits (methods: classifications with mainly FDA and machine learning with Random Forest).

In a second approach, I investigated temporal modifications of biological traits and their implications for fish demography. Thanks to a collection of past (1980) and present otoliths (2011), I monitored temporal variations of growth, migration and diet in an emblematic declining species of Terminos Bairdiella chrysoura(study of otolith growth, elemental microchemistry and δ13C and δ15N composition). This study detected a diet modification and a growth decrease probably in relation with a shift of the habitat use at juvenile stage. These modifications of life history traits directly linked to individual fitness, allowed to make hypothesis about mechanisms leading to B. chrysoura‘s decline and thus to provide recommendations for population protection.

After my PhD, I wanted to continue exploring the effects of human activities on fish trophic ecology and I chose to focus my research on the impacts that fishing activities have on marine food webs. My main questions are:

– Do fishing activities lead to a change in species diet?
– Do these activities lead to a change in the trophic level and/or the source of organic matter of the marine fish populations?
– Are some feeding strategies more preserved/threatened than others by these disturbances?

To tackle these questions, I first reconstruct the trophic ecology of fishes caught in the Faroes between 1950 and 2014 thanks to the stable isotopic signature of their otoliths (d13C and d15N of the otolith organic matter) and then I model the effects of fishing activities on these signatures.


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