The life cycle of benthic invertebrate species is generally characterized by a succession of contrasting developmental stages, including a pelagic larval stage closely conditioned by hydrodynamics, and the juvenile and adult benthic stages associated with the substrate. Different interactions with biotic and abiotic factors are involved throughout these development phases, contributing to the spatial and temporal dynamics of benthic populations and communities. The MODELISME project aims to improve the understanding of certain mechanisms that affect benthic invertebrates during the (1) pelagic larval and (2) substrate recruitment phases by using modelling tools, combined with in situ observations and genetic analyses. In particular, the project proposes to study:
(1) When pelagic larvae disperse with currents, both larval behaviour and ecology (date and duration of laying; survival; development time) and hydrodynamic conditions that influence larval fate and connectivity between spawning and larval recruitment areas (Ellien et al., 2004, Paris et al., 2007, Nicolle et al., 2013).
(2) During the colonization of the substrate by larvae, which represents a critical phase of the life cycle, affinity with sediment, tropism towards established adult populations or adapted habitat.
The project focuses on several benthic species of the Rade de Brest characterized by contrasting larval life cycles, distinct spatial distributions (partly stratified) and divergent demographic histories (expansion and/or decline). The expected results will aim to characterize the spatial variability of recruitment for these different species, and to quantify the effects of ecology and larval behaviour on connectivity (contrast between species), the effects of environmental gradients (Alder vs Elorn) on recruitment success, and for some species, the contribution of external larval inputs to the Rade de Brest (connectivity with the Iroise Sea).