Laure Regnier Brisson's thesis defense

Laure Regnier Brisson, a doctoral student in the Coastal Benthic Ecology laboratory of the Coastal Ecosystem Dynamics unit, will defend his thesis on Monday 8 February 2024 at 1:30 pm at the IUEM in Plouzané (amphitheatre A):

Ecology & growth dynamics of the variegated scallop (Mimachlamys varia) in the Bay of Brest

Abstract : The variegated scallop, Mimachlamys varia (Linnaeus, 1758), is a scallop found on the northeast Atlantic coast and historically fished in France, but in decline since the 1970s. To reverse the observed stock declines and ensure a sustainable fishery, we carried out an integrative approach through an extensive study of its ecology and biological traits to better understand how and to which extent its growth, reproduction and trophic ecology vary depending on spatio-temporal variations in environmental conditions. For this purpose, we combined various approaches: in-situ observations, controlled experiments and modeling. In the Bay of Brest, the observed growth performance is lower than in the 1990’s, while the commercial size is barely reached even after three years of growth. Temperature and food availability influenced both the growth and the reproduction, resulting in spatio-temporal variations in M.varia demographic parameters. For example, a lower demographic performance is observed when temperature is too high, and/or when the accessibility to trophic resources is limited. By combining the estimated demographic parameters with isotopic measurements we parameterized a dynamic energy budget model revealing that M. varia feeds preferentially on fresh phytoplankton, but is still able to use different resources, with a variable feeding efficiency over time. Based on these results, recommendations are proposed for restoring M. varia populations in the Bay of Brest.